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Astronomy Picture of the Day |
APOD: 2025 March 14 - Moon Pi and Mountain Shadow
Explanation:
What phase of the Moon is 3.14 radians
from the Sun?
The Full Moon, of course.
Even though the
Moon might look full
for several days, the Moon is truly at its full phase when it is
Pi radians
(aka 180 degrees) from the Sun in
ecliptic longitude.
That's opposite the Sun in planet Earth's sky.
Rising as the Sun set on March 9, 2020, only an hour or so after the
moment of its full phase, this orange tinted and
slightly flattened
Moon still looked full.
It was photographed opposite the setting Sun from Teide National Park
on the Canary Island of Tenerife.
Also opposite the setting Sun, seen from near the Teide volcano peak
about 3,500 meters above sea level, is the mountain's rising
triangular shadow
extending into Earth's dense atmosphere.
Below the distant ridge line on the left are the
white telescope domes of
Teide Observatory.
Today, March 14 2025, the moon is
Pi radians from the Sun at exactly 06:55 UTC.
That's about three minutes before the midpoint of the March Full Moon's
total lunar eclipse.
APOD: 2025 January 18 - Full Moon, Full Mars
Explanation:
On January 13
a Full Moon and a Full Mars were close,
both bright and opposite the Sun in planet Earth's sky.
In fact
Mars was occulted, passing behind the Moon, when
viewed from some locations in North America and northwest Africa.
As seen from Richmond, Virginia, USA, this composite
image sequence follows the evening
lunar occultation before, during, and after the much anticipated
celestial spectacle.
The telescopic time series is constructed from an exposure made every two
minutes while tracking the Moon over the hours encompassing the event.
As a result, the Red Planet's trajectory seems to follow
a gently curved path due to the
Moon's slightly different rate of apparent motion.
The next lunar occultation of bright planet Mars will be
on February 9 when the moon is in a waxing gibbous phase.
Lunar occultations are only ever visible from a fraction of the
Earth's surface, though.
The
February 9 occultation of Mars will be seen from parts of
Russia, China, eastern Canada, Greenland and other
(mostly northern) locations,
but a close conjunction of a bright Moon with Mars will be more
widely visible from planet Earth.
APOD: 2025 January 15 – Wolf Moon Engulfs Mars
Explanation:
Does the Moon ever engulf Mars?
Yes, but only in the sense that it moves in front, which happens on
rare occasions.
This happened just yesterday, though, as seen from some locations in
North America and western Africa.
This occultation was notable
not only because the Moon was a fully lit
Wolf Moon, but because Mars was near its largest and brightest, moving to
opposition -- the closest to the Earth in its orbit -- only tomorrow.
The engulfing, more formally called an
occultation, typically lasts about an hour.
The featured image was taken from near
Chicago,
Illinois,
USA just as
Earth's largest satellite
was angularly moving away from the much more distant
red planet.
Our
Moon
occasionally moves in front of all of the
Solar System's planets.
Given the temporary alignment of
orbital planes, the
next time our
Moon eclipses Mars
will be a relatively soon February 9.
APOD: 2024 December 20 - The Long Night Moon
Explanation:
On the night of December 15, the
Full Moon was bright.
Known to some as the Cold Moon
or the Long Night Moon, it was the closest Full Moon
to the northern winter solstice and the
last Full Moon of 2024.
This Full Moon was also at a
major lunar standstill.
A major lunar standstill is
an extreme in
the monthly north-south range of moonrise and moonset caused by the
precession of the Moon's orbit over an
18.6 year cycle.
As a result, the full lunar phase was near the Moon's northernmost moonrise
(and moonset) along the horizon.
December's Full Moon is rising in this stacked image, a
composite of exposures recording the range of brightness visible
to the eye on the northern winter night.
Along with a colorful
lunar corona and aircraft contrail
this Long Night Moon shines in a cold sky
above the rugged, snowy peaks of the Italian Dolomites.
APOD: 2024 September 20 - A Hazy Harvest Moon
Explanation:
For northern hemisphere dwellers, September's Full Moon was
the Harvest Moon.
On September 17/18 the sunlit lunar nearside passed into shadow, just
grazing Earth's umbra, the planet's dark, central shadow cone, in a
partial lunar eclipse.
Over the two and a half hours before dawn
a camera fixed to a tripod
was used to record this
series of exposures
as the eclipsed Harvest Moon set behind Spiš Castle
in the hazy morning sky over eastern Slovakia.
Famed in festival, story, and song,
Harvest Moon is just the traditional name of the full moon nearest the
autumnal
equinox.
According to lore the name is a fitting one.
Despite the diminishing daylight hours as the
growing season
drew to a close, farmers could harvest crops by the light of a full moon
shining on
from dusk to dawn.
This September's Harvest Moon was also known to some as a supermoon,
a term becoming a traditional name for a
full moon near perigee.
APOD: 2024 September 15 – Find the Man in the Moon
Explanation:
Have you ever seen the Man in the Moon?
This common question plays on the ability of humans to see
pareidolia --
imagining familiar icons where they don't actually exist.
The textured surface of Earth's
full Moon
is home to numerous identifications of iconic objects,
not only in modern western culture but in
world folklore throughout history.
Examples, typically dependent on
the Moon's perceived orientation,
include the
Woman in the Moon and the
Rabbit in the Moon.
One facial outline commonly identified as the
Man in the Moon
starts by imagining the two dark circular areas --
lunar maria -- here just above
the Moon's center, to be the eyes.
Surprisingly, there
actually is a man in this Moon image -- a
close look
will reveal a real person -- with a telescope --
silhouetted against the Moon.
This well-planned image was taken in 2016 in
Cadalso de los Vidrios in
Madrid,
Spain.
APOD: 2024 September 3 – Quarter Moon and Sister Stars
Explanation:
Nine days ago, two quite different sky icons were imaged rising together.
Specifically, Earth's Moon shared the eastern
sky with the
sister stars of the Pleiades cluster, as viewed from
Alberta,
Canada.
Astronomical images of the
well-known Pleiades
often show the star cluster's alluring blue
reflection nebulas, but here they are washed-out by the
orange moonrise sky.
The half-lit Moon, known as a
quarter moon, is overexposed, although
the outline of the dim lunar night side can be seen by illuminating
earthshine, light first reflected
from the Earth.
The featured image is a composite of
eight successive exposures with
brightnesses adjusted to match what the
human eye would see.
The Moon passes
nearly -- or
directly -- in front of
the Pleaides once a month.
APOD: 2024 August 27 – Moon Eclipses Saturn
Explanation:
What if Saturn disappeared?
Sometimes, it does.
It doesn't really go away, though, it just disappears from view when our
Moon moves in front.
Such a Saturnian eclipse, more formally called an
occultation, was visible along a
long swath of Earth -- from
Peru,
across the Atlantic Ocean, to
Italy --
only a few days ago.
The
featured color image is a digital fusion of the
clearest images captured during
the event
and rebalanced for color and relative brightness between
the relatively dim Saturn and the comparatively bright Moon.
Saturn and the
comparative bright Moon.
The exposures were all taken from
Breda,
Catalonia,
Spain,
just before occultation.
Eclipses of Saturn by
our Moon will occur
each month for the rest of this year.
Each time, though, the fleeting event will be visible
only to those with clear skies -- and the right
location on
Earth.
APOD: 2024 July 27 - Saturn at the Moon's Edge
Explanation:
Saturn now rises before midnight in planet Earth's sky.
On July 24, the naked-eye planet
was in close conjunction,
close on the sky,
to a waning gibbous Moon.
But from some locations on planet Earth the
ringed gas giant
was occulted,
disappearing behind
the Moon for about an hour
from skies over parts of Asia and Africa.
Because the Moon and bright planets wander through the sky near the
ecliptic plane, such
occultation events are
not uncommon, but they can be
dramatic.
In this telescopic view from Nanjing, Jiangsu, China,
Saturn is caught moments before
its disappearance behind the lunar disk.
The snapshot gives the illusion
that Saturn hangs just above
Glushko crater,
a
43 kilometer diameter,
young, ray crater near the Moon's western edge.
Of course, the Moon is 400 thousand kilometers away,
compared to Saturn's distance of 1.4
billion kilometers.
APOD: 2024 July 24 – Exaggerated Moon
Explanation:
Our Moon doesn't really have craters this big.
Earth's Moon, Luna, also doesn't naturally show this spikey texture,
and its colors are more subtle.
But this digital creation is based on reality.
The featured image is a digital composite of a good Moon image
and surface height data taken from NASA's
Lunar Orbiter Laser Altimeter (LOLA) mission
-- and then exaggerated for
educational understanding.
The digital enhancements, for example, accentuate lunar highlands and
show more clearly craters that illustrate the
tremendous bombardment our Moon has been through during its
4.6-billion-year history.
The dark areas, called
maria,
have fewer craters and were once seas of
molten lava.
Additionally, the image
colors, although based on the
moon's real composition, are changed and exaggerated.
Here, a blue hue indicates a region that is
iron rich, while orange indicates a slight excess of
aluminum.
Although the
Moon has shown the same side to the Earth for billions of years,
modern technology is allowing humanity to learn
much more about it -- and how it
affects the Earth.
APOD: 2024 June 29 - A Solstice Moon
Explanation:
Rising opposite the setting Sun,
June's Full Moon
occurred within about 28 hours of the solstice.
The Moon stays close to the Sun's path along the ecliptic plane
and so while the solstice Sun climbed
high in daytime skies, June's
Full Moon remained low that night
as seen from northern latitudes.
In fact, the Full Moon hugs the horizon in this June 21 rooftop night sky
view from Bursa, Turkey, constructed from exposures made every 10 minutes
between moonrise and moonset.
In 2024 the Moon also reached a
major lunar standstill,
an extreme in the
monthly north-south
range of moonrise and moonset
caused by the precession of the Moon's orbit over an
18.6 year cycle.
As a result, this June
solstice Full Moon was at its southernmost moonrise and moonset
along the horizon.
APOD: 2024 June 20 - Sandy and the Moon Halo
Explanation:
Last April's Full Moon shines
through high clouds
near the horizon,
casting shadows in this garden-at-night skyscape.
Along with canine sentinel Sandy watching the garden gate,
the wide-angle snapshot also captured the
bright Moon's
22 degree ice halo.
But June's bright Full Moon will cast shadows too.
This month, the Moon's
exact full phase occurs at 01:08 UTC June 22.
That's a mere 28 hours or so after
today's June solstice
(at 20:51 UTC June 20), the moment when the Sun reaches
its maximum northern declination.
Known to some as a Strawberry Moon, June's Full Moon is
at its southernmost declination, and of course will create its own
22 degree halos
in hazy night skies.
APOD: 2024 June 2 – Rotating Moon from LRO
Explanation:
No one, presently, sees the Moon rotate like this.
That's because the Earth's moon is tidally locked to the Earth, showing us
only one side.
Given modern digital technology, however,
combined with many detailed images returned by the
Lunar Reconnaissance Orbiter (LRO),
a high resolution virtual
Moon rotation movie
has been composed.
The featured time-lapse video starts with the standard Earth
view of the Moon.
Quickly, though,
Mare Orientale, a large crater with a dark center
that is difficult to see from the Earth, rotates into view just below the equator.
From an entire
lunar month condensed into 24 seconds,
the video clearly shows that the Earth side of
the Moon contains an abundance of
dark lunar maria,
while the lunar far side is dominated by bright
lunar highlands.
Currently, over 32 new missions to the Moon are under active development from multiple countries and companies, including NASA's
Artemis program which aims to
land people on the Moon again within the next few years.
APOD: 2024 March 14 - Moon Pi and Mountain Shadow
Explanation:
What phase of the Moon is 3.14 radians from the Sun?
The Full Moon, of course.
Even though the
Moon might look full
for several days, the Moon is truly at its full phase when it is
Pi radians
(aka 180 degrees) from the Sun in ecliptic longitude.
That's opposite the Sun in planet Earth's sky.
Rising as the Sun set on March 9, 2020, only an hour or so after the moment of
its full phase, this orange tinted and
slightly flattened
Moon still looked full.
It was photographed opposite the setting Sun from Teide National Park
on the Canary Island of Tenerife.
Also opposite the setting Sun, seen from near the Teide volcano peak
about 3,500 meters above sea level, is the mountain's rising
triangular shadow
extending into Earth's dense atmosphere.
Below the distant ridge line on the left are the
white telescope domes of
Teide Observatory.
Again Pi radians from the Sun, on March 25 the Full Moon will dim
slightly as it glides through Earth's outer shadow in a
penumbral lunar eclipse.
APOD: 2024 February 26 – Martian Moon Eclipses Martian Moon
Explanation:
What if there were two moons in the sky -- and they eclipsed each other?
This happens on
Mars.
The
featured video shows a version of this unusual eclipse from space.
Pictured are the two moons of Mars: the larger
Phobos,
which orbits closer to the red planet, and the smaller
Deimos, which orbits further out.
The sequence was captured last year by the
ESA’s
Mars Express,
a robotic spacecraft that itself orbits
Mars.
A similar
eclipse is visible
from the Martian surface, although very rarely.
From the surface, though, the closer moon
Phobos would appear
to pass in front of farther moon Deimos.
Most oddly,
Phobos orbits Mars so close that it appears to
move backwards when compared to
Earth's Moon from Earth,
rising in west and setting in the east.
Phobos, the closer moon,
orbits so close and so fast that it passes
nearly overhead about three times a day.
APOD: 2024 February 13 – A January Wolf Moon
Explanation:
Did you see the full moon last month?
During every month, on average, a
full moon occurs in the skies over
planet Earth.
This is because
the Moon takes a
month
to complete another orbit around our
home planet,
goes through all of its
phases, and once
again has its entire
Earth-facing half lit by reflected sunlight.
Many indigenous cultures give each full moon a name, and this past full moon's
names include the Ice Moon, the Stay at Home Moon, and the Quiet Moon.
Occurring in January on the
modern western calendar,
several cultures have also named the most recent full moon the
Wolf Moon, in honor of the
famous howling animal.
Featured here above the Italian
Alps mountains,
this past
Wolf Moon was captured in combined long and short exposure images.
The image is
striking because, to some,
the surrounding clouds appear as a wolf's mouth ready to swallow the
Wolf Moon, while others see the Moon as a wolf's eye.
APOD: 2024 February 11 – Rocket Plume Shadow Points to the Moon
Explanation:
Why would the shadow of a
rocket's launch plume point toward the Moon?
In early 2001 during a launch of the
space shuttle
Atlantis,
the Sun,
Earth,
Moon,
and rocket were all properly aligned for
this photogenic coincidence.
First, for the
space shuttle's plume to cast a long shadow,
the time of day must be either near
sunrise or
sunset.
Only then will the
shadow
be its longest and extend all the way to the
horizon.
Finally, during a
Full Moon, the
Sun and
Moon are on
opposite sides of the sky.
Just after
sunset, for example,
the Sun is slightly below the
horizon, and,
in the other direction, the Moon is slightly above the horizon.
Therefore, as
Atlantis blasted off, just after
sunset,
its shadow projected away from the Sun toward the
opposite horizon, where the
Full Moon happened to be.
APOD: 2024 January 30 – SLIM Lands on the Moon
Explanation:
New landers are on the Moon.
Nearly two weeks ago,
Japan's
Smart Lander for Investigating Moon
(SLIM) released two rovers as it descended, before its main lander
touched down itself.
The larger of the two rovers can
hop like a frog,
while the smaller rover is about the size of a
baseball and can move after
pulling itself apart like a
transformer.
The main lander, nicknamed Moon Sniper, is seen in the
featured image taken by the smaller rover.
Inspection of the image shows that
Moon Sniper's thrusters are facing up,
meaning that the lander is
upside down from its descent configuration and
on its side from its intended
landing configuration.
One result is that
Moon Sniper's
solar panels are not in the
expected orientation, so that
powering the lander had to be curtailed and adapted.
SLIM's lander has
already succeeded as a technology demonstration,
its main mission, but was not
designed to withstand the lunar night -- which
starts tomorrow.
APOD: 2024 January 27 - Full Observatory Moon
Explanation:
A popular name
for January's full moon in the northern hemisphere is
the Full Wolf Moon.
As the new year's first full moon, it rises over Las Campanas Observatory
in this dramatic
Earth-and-moonscape.
Peering from the foreground like astronomical eyes are
the observatory's twin 6.5 meter diameter Magellan telescopes.
The snapshot was captured with telephoto lens
across rugged terrain in the Chilean Atacama Desert,
taken at a distance of about 9 miles from the observatory
and about 240,000 miles from
the lunar surface.
Of course the first full moon of the
lunar new year,
known to some as
the Full Snow Moon, will rise on February 24.
APOD: 2024 January 24 – Earth and Moon from Beyond
Explanation:
What do the Earth and Moon look like from beyond the Moon?
Although
frequently
photographed
together, the familiar duo was captured with this unusual perspective in late 2022 by the robotic
Orion spacecraft of
NASA's
Artemis I
mission as it looped around Earth's most massive satellite and
looked back toward its home world.
Since our
Earth
is about four times the diameter of the
Moon, the satellite’s
seemingly large size was caused by the capsule
being closer to the smaller body.
Artemis II,
the next launch in NASA’s Artemis series,
is currently scheduled to take people around the Moon in 2025, while
Artemis III
is planned to return humans to
lunar surface in late 2026.
Last week,
JAXA's robotic
SLIM
spacecraft, launched from
Japan,
landed on the Moon and released two hopping rovers.
APOD: 2024 January 2 – Rocket Transits Rippling Moon
Explanation:
Can a rocket make the Moon ripple?
No, but it can make a background moon appear
wavy.
The rocket, in this case, was a
SpaceX
Falcon Heavy that blasted off from
NASA's
Kennedy Space Center last week.
In the
featured launch picture,
the rocket's exhaust plume glows beyond its projection
onto the distant, rising, and nearly full moon.
Oddly, the Moon's lower edge shows
unusual drip-like ripples.
The Moon itself,
far in the distance, was really unchanged.
The physical cause of these
apparent ripples
was pockets of relatively hot or rarefied air
deflecting moonlight less strongly than
pockets of relatively cool or compressed air:
refraction.
Although the shot was planned, the timing of
the launch
had to be just right for the rocket to be
transiting the Moon during this single exposure.
APOD: 2023 December 3 – Moon Setting Behind Teide Volcano
Explanation:
These people are not in danger.
What is coming down from the left is just the Moon, far in the distance.
Luna appears so large here because she is being
photographed through a telescopic lens.
What is moving is mostly
the Earth, whose spin causes
the Moon to slowly disappear behind
Mount Teide,
a volcano in the
Canary Islands
off the northwest coast of
Africa.
The people pictured are
16 kilometers away and
many are facing the camera because they are watching
the Sun rise behind the photographer.
It is not a
coincidence that a
full moon rises just when the
Sun sets because the Sun is always on the
opposite side of the sky from a full moon.
The featured video
was made in 2018 during the full
Milk Moon.
The video is not time-lapse --
this was really how fast
the Moon was setting.
APOD: 2023 November 12 – Gibbous Moon beyond Swedish Mountain
Explanation:
This is a gibbous Moon.
More Earthlings
are familiar with a full moon, when the entire face of
Luna is lit by the
Sun,
and a crescent moon,
when only a sliver of the
Moon's face is lit.
When more than half of the Moon is illuminated, though,
but still short of full illumination, the
phase
is called gibbous.
Rarely seen in television and movies,
gibbous moons
are quite common in the actual night sky.
The featured image was taken in
Jämtland,
Sweden
near the end of 2018 October.
That gibbous moon turned, in a few days, into a crescent moon, and then a
new moon,
then back to a crescent, and a few days past that, back to gibbous.
Setting up to capture a picturesque gibbous moonscape, the photographer was
quite surprised to find an airplane,
surely well in the foreground,
appearing to fly past it.
APOD: 2023 September 30 - A Harvest Moon over Tuscany
Explanation:
For northern hemisphere dwellers, September's Full Moon was
the Harvest Moon.
Reflecting warm hues at sunset, it rises
behind cypress trees huddled on a hill top in Tuscany, Italy
in this telephoto view from September 28.
Famed in festival, story, and song,
Harvest Moon is just the traditional name of the full moon nearest the
autumnal
equinox.
According to lore the name is a fitting one.
Despite the diminishing daylight hours as the
growing season
drew to a close, farmers could harvest crops by the light of a full moon
shining on
from dusk to dawn.
This Harvest Moon was also known to some as a supermoon,
a term becoming a traditional name for a
full
moon near perigee.
It was the fourth and final supermoon
for 2023.
APOD: 2023 September 17 – Moon Mountains Magnified during Ring of Fire Eclipse
Explanation:
What are those dark streaks in this composite image of a solar eclipse?
They are reversed shadows of mountains at the edge of the Moon.
The center image, captured from
Xiamen,
China,
has the Moon's center directly in front of the Sun's center.
The Moon, though, was
too far from
the Earth to completely block the entire Sun.
Light that streamed around the edges of the Moon is called a
ring of fire.
Images at each end of the sequence show
sunlight that streamed through lunar valleys.
As the Moon moved further in front of the Sun, left to right,
only the higher peaks on the Moon's perimeter could block sunlight.
Therefore, the dark streaks are projected,
distorted, reversed, and magnified
shadows of mountains at the Moon's edge.
Bright areas are called
Baily's Beads.
Only people in a narrow swath across Earth's
Eastern Hemisphere
were able to view this full annular solar eclipse in 2020.
Next month, though, a narrow swath crossing
both North and South America
will be exposed to the
next
annular solar eclipse.
And next April, a
total solar eclipse will be visible across
North America.
APOD: 2023 August 8 – Moon Meets Jupiter
Explanation:
What's that below the Moon?
Jupiter -- and its largest moons.
Many
skygazers across planet Earth enjoyed the close conjunction of
Earth's Moon passing nearly in front of Jupiter in mid-June.
The featured image is a single exposure of the event taken from
Morón de la Frontera,
Spain.
The sunlit lunar crescent on the left is overexposed, while the Moon's night side,
on the right, is only faintly illuminated by Earthshine.
Lined up diagonally below the Moon, left to right, are
Jupiter's bright Galilean satellites:
Callisto,
Ganymede,
Io
(hard to see as it is very near to Jupiter), and
Europa.
In fact, Callisto, Ganymede, and Io are larger than Earth's Moon, while
Europa is only slightly smaller.
NASA's robotic spacecraft
Juno
is currently orbiting Jupiter and made a
close pass near Io only a week ago.
If you
look up in the
night sky tonight, you will again see two of the brightest
objects angularly close together -- because
tonight is another
Moon-Jupiter conjunction.
APOD: 2023 May 24 – Observatory Aligned with Moon Occulting Jupiter
Explanation:
Sometimes we witness the
Moon moving directly in front of -- called occulting -- one of the planets in our
Solar System.
Earlier this month that planet was Jupiter.
Captured here was the moment when
Jupiter re-appeared from
behind the surface of our Moon.
The Moon was in its
third quarter, two days before the dark
New Moon.
Now, our
Moon is continuously
half lit by the Sun, but when in its third quarter,
relatively little of that half can be seen from the
Earth.
Pictured, the Moon itself was aligned behind the famous
Lick Observatory in
California,
USA,
on the summit of
Mount Hamilton.
Coincidentally, Lick enabled the discovery of a moon of Jupiter:
Amalthea, the last visually detected moon of Jupiter after
Galileo's
observations.
APOD: 2023 April 30 – Saturn's Moon Helene in Color
Explanation:
Although its colors may be subtle, Saturn's moon Helene is an enigma in any light.
The moon was imaged in
unprecedented detail in 2012 as the
robotic Cassini spacecraft orbiting Saturn
swooped
to within a single Earth diameter of the
diminutive moon.
Although conventional craters and hills
appear, the
above
image also
shows terrain that appears unusually smooth and streaked.
Planetary astronomers are inspecting these detailed images of
Helene to
glean clues
about the origin and evolution of the 30-km across floating iceberg.
Helene is also unusual because it circles
Saturn just ahead of the large moon
Dione, making it one of only
four known
Saturnian moons to occupy a gravitational dimple known as a stable
Lagrange point.
APOD: 2023 February 28 – Crescent Moon Beyond Greek Temple
Explanation:
Why is a thin crescent moon never seen far from a horizon?
Because the only
geometry that gives a thin crescent lunar phase occurs when
the Moon
appears close to
the Sun
in the sky.
The crescent is not caused by the
shadow of the Earth,
but by seeing only a small part of the Moon directly illuminated by the Sun.
Moreover, the thickest part of the
crescent always occurs in the direction of the Sun.
In the evening, a
thin crescent Moon will set
shortly after the Sun and not be seen for the rest of the night.
Alternatively, in the morning, a
crescent Moon will rise shortly before the Sun after not being seen for most of the night.
Pictured two weeks ago, a crescent moon was captured near the horizon, just before sunrise, far behind remnants of the ancient
Temple of
Poseidon in
Greece.
APOD: 2023 January 16 – Moon Enhanced
Explanation:
Our Moon doesn't really look like this.
Earth's Moon, Luna, doesn't naturally show this rich texture,
and its colors are more subtle.
But this digital creation is based on reality.
The featured image is a composite of multiple images and
enhanced to bring up real surface features.
The enhancements, for example, show more clearly craters that illustrate the
tremendous bombardment our Moon has been through during its
4.6-billion-year history.
The dark areas, called
maria,
have fewer craters and were once seas of
molten lava.
Additionally, the image
colors, although based on the
moon's real composition, are changed and exaggerated.
Here, a blue hue indicates a region that is iron rich,
while orange indicates a slight excess of aluminum.
Although the
Moon has shown the same side to the Earth for billions of years,
modern technology is allowing humanity to learn
much more about it -- and how it
affects the Earth.
APOD: 2023 January 6 - Moon O'Clock 2022
Explanation:
The first Full Moon of 2023
is in
the sky tonight
opposite the Sun at 23:08
UTC.
Big and beautiful, the Moon at its
brightest phase should be easy to spot.
Still, for quick reference images captured near the times of
all the full moons of 2022 are aranged in this
dedicated astro-imaging project
from Sri Lanka, planet Earth.
The day, month, and a traditional popular name for 2022's twelve full moons
are given in the chart.
The apparent size of each full moon depends
on how close the full lunar phase is to
perigee or apogee,
the closest or farthest point in the Moon's elliptical orbit.
Like the 2022 Wolf Moon at the 1 o'clock position,
tonight's Full Moon occurs within about two days of apogee.
But unlike in 2022,
the year 2023
will have 13 full moons that
won't all fit nicely on the twelve hour clock.
APOD: 2022 December 15 - Full Moon, Full Mars
Explanation:
On December 8
a full Moon and a full Mars were close,
both bright and opposite the Sun in planet Earth's sky.
In fact
Mars was occulted, passing behind the Moon when
viewed from some locations across Europe and North America.
Seen from the city of Kosice in eastern Slovakia,
the lunar occultation of Mars happened just before sunrise.
The tantalizing spectacle
was recorded in this telescopic timelapse
sequence of exposures.
It took about an hour for the
Red Planet to disappear behind the
lunar disk and
then reappear as a
warm-hued full Moon,
the last full Moon of 2022, sank toward the western horizon.
The next lunar occultation of bright planet Mars will be in the new year
on January 3, when the Moon is in a waxing gibbous phase.
Lunar occultations
are only ever visible from a fraction of the
Earth's surface, though.
The January 3 occultation
of Mars will be visible from parts of the
South Atlantic, southern Africa, and the Indian Ocean.
APOD: 2022 October 14 - The Falcon and the Hunter's Moon
Explanation:
The Full Moon of October 9th
was the second Full Moon after the
northern hemisphere autumnal equinox, traditionally called the
Hunter's Moon.
According to lore, the name is a fitting one because this
Full Moon lights the night during a time for hunting
in preparation for the coming winter months.
In this snapshot, a nearly full Hunter's Moon
was captured just after sunset on October 8, rising in skies over
Florida's Space Coast.
Rising from planet Earth
a Falcon 9 rocket pierces the bright lunar disk
from the photographer's vantage point.
Ripples and fringes along the edge of the lunar disk appear as
supersonic
shock waves generated by the
rocket's passage
change the atmosphere's index of refraction.
APOD: 2022 September 15 - Harvest Moon over Sicily
Explanation:
For northern hemisphere dwellers,
September's Full Moon
was the Harvest Moon.
Reflecting warm hues at sunset it rises
over the historic town of Castiglione di Sicilia in
this telephoto view
from September 9.
Famed in festival, story, and song
Harvest Moon
is just the traditional name of the full moon nearest
the autumnal equinox.
According to lore the name is a fitting one.
Despite the diminishing daylight hours as the growing season drew
to a close, farmers could harvest crops by the light of a full moon
shining on
from dusk to dawn.
APOD: 2022 July 25 - Find the New Moon
Explanation:
Can you find the Moon?
This usually simple task can be quite difficult.
Even though the Moon is above your horizon half of the time, its
phase can be
anything from crescent to full.
The featured image was taken in late May from
Sant Martà d'Empúries,
Spain, over the
Mediterranean Sea in the early morning.
One reason
you can't find
this moon is because it is very near to its
new phase,
when very little of the half illuminated by
the Sun is visible to the Earth.
Another reason is because this moon is
near the horizon
and so seen through a long path of
Earth's atmosphere -- a path which
dims the already faint crescent.
Any crescent moon is
only visible near the direction the Sun,
and so only locatable near sunrise or sunset.
The Moon
runs through all of its
phases in a month
(moon-th),
and this month the thinnest
sliver of a crescent -- a new moon --
will occur in three days.
APOD: 2022 June 12 - Find the Man in the Moon
Explanation:
Have you ever seen the Man in the Moon?
This common question plays on the ability of humans to see
pareidolia --
imagining familiar icons where they don't actually exist.
The textured surface of Earth's
full Moon
is home to numerous identifications of iconic objects,
not only in modern western culture but in
world folklore throughout history.
Examples, typically dependent on
the Moon's perceived orientation, include the
Woman in the Moon and the
Rabbit in the Moon.
One facial outline commonly identified as the
Man in the Moon
starts by imagining the two dark circular areas --
lunar maria -- here just above
the Moon's center, to be the eyes.
Surprisingly, there
actually is a man in this Moon image -- a
close look
will reveal a real person -- with a telescope --
silhouetted against the Moon.
This featured well-planned image was taken in 2016 in
Cadalso de los Vidrios in
Madrid,
Spain.
Do you have a
favorite object that you see in the Moon?
APOD: 2022 May 15 - Colors of the Moon
Explanation:
What color is the Moon?
It depends on the night.
Outside of the Earth's atmosphere, the
dark Moon,
which shines by reflected sunlight, appears a
magnificently brown-tinged gray.
Viewed from inside the
Earth's atmosphere, though, the moon can appear quite different.
The featured image highlights a collection of apparent colors of the full moon documented by one astrophotographer over 10 years from
different locations across
Italy.
A
red or yellow colored moon usually indicates a moon seen near the horizon.
There, some of the
blue light has been scattered away
by a long path through the
Earth's atmosphere,
sometimes laden with fine dust.
A blue-colored moon is more rare and
can indicate a moon seen through an atmosphere carrying larger dust particles.
What created the purple moon is
unclear --
it may be a combination of several effects.
The last image captures the
total lunar eclipse of 2018 July --
where the moon,
in Earth's shadow, appeared a
faint red -- due to light
refracted through
air around the
Earth.
Today there is not only another full moon but a
total lunar eclipse visible to observers
in North and
South America --
an occurrence that may lead to some
unexpected lunar colorings.
APOD: 2022 February 28 - Direct Projection: The Moon in My Hands
Explanation:
You don't have to look through a telescope to know where it's pointing.
Allowing the telescope to project its image onto a
large surface can be useful because it dilutes the
intense brightness of
very bright sources.
Such dilution is useful for looking at
the Sun,
for example during a
solar eclipse.
In the featured single-exposure image, though, it is a
too-bright
full moon that is projected.
This February full moon occurred two weeks ago and is
called the Snow Moon by some northern cultures.
The projecting instrument is the main 62-centimeter telescope at the
Saint-Véran
Observatory high in the French
Alps.
Seeing a full moon directly is easier because it is not
too bright, although you won't see this level of detail.
Your next chance
will occur on March 17.
APOD: 2022 February 15 - Terminator Moon
Explanation:
What's different about this Moon?
It's the terminators.
In the featured image, you can't directly see any
terminator --
the line that divides the light of day from the dark of night.
That's because the image is a digital composite of 29 near-terminator lunar strips.
Terminator regions show the longest and most
prominent shadows -- shadows which, by their contrast and length, allow a flat photograph to appear three-dimensional.
The original images
and data were taken near the
Moon
by NASA's
Lunar Reconnaissance Orbiter.
Many of the Moon's
craters
stand out because of the
shadows they all cast to the right.
The image shows in graphic detail that the
darker regions known as maria are not just darker than the rest of the
Moon -- they are flatter.
APOD: 2022 February 1 - Moon Phases 2022
Explanation:
What will the Moon phase be on your birthday this year?
It is
hard to predict because the
Moon's appearance changes nightly.
As the
Moon orbits the
Earth,
the half illuminated by the
Sun
first becomes increasingly visible, then decreasingly visible.
The featured video animates images and altitude data
taken by NASA's Moon-orbiting
Lunar Reconnaissance Orbiter to show all
12 lunations that appear this year, 2022 --
as seen from Earth's northern
(southern)
hemisphere.
A single
lunation
describes one full cycle of our Moon, including all of its
phases.
A full
lunation takes about 29.5 days, just under a month
(moon-th).
As each
lunation progresses, sunlight reflects from the
Moon at different angles, and so
illuminates different features differently.
During all of this, of course,
the Moon
always keeps the same face toward the
Earth.
What is less apparent night-to-night is that
the Moon's apparent size changes slightly,
and that a slight wobble called a
libration occurs as the
Moon progresses along its elliptical orbit.
APOD: 2022 January 1 - The Full Moon of 2021
Explanation:
Every Full Moon of 2021 shines in this year-spanning astrophoto project,
a composite portrait of
the familiar lunar nearside at each brightest
lunar phase.
Arranged by moonth,
the year progresses in stripes beginning at the top.
Taken with the same camera and lens the stripes are from Full Moon
images all combined at the same pixel scale.
The stripes still look mismatched, but they show
that the Full Moon's angular size changes throughout the year
depending on its
distance from Kolkata, India, planet Earth.
The calendar month,
a full moon name, distance in kilometers, and angular
size is indicated for each stripe.
Angular size is given in minutes of arc corresponding to 1/60th of a degree.
The largest Full Moon is
near a perigee or closest approach
in May.
The smallest is
near an apogee,
the most distant Full Moon in December.
Of course the full moons of
May and November
also slid into Earth's shadow
during 2021's two lunar eclipses.
APOD: 2021 December 1 - A Blue Banded Blood Moon
Explanation:
What causes a blue band to cross the Moon during a lunar eclipse?
The blue band is real but usually quite hard to see.
The featured HDR image of last week's lunar eclipse, however -- taken from
Yancheng,
China --
has been digitally processed to equalize the
Moon's brightness and exaggerate
the colors.
The gray color of the bottom right is
the Moon's natural color, directly illuminated by sunlight.
The upper left part of the Moon is not directly lit by the Sun since it is
being eclipsed -- it in the
Earth's shadow.
It is faintly lit, though, by sunlight that has passed deep through
Earth's atmosphere.
This part of the Moon is red -- and called a
blood Moon -- for the same reason that Earth's sunsets are red:
because air scatters away
more blue light than red.
The unusual blue band is different -- its color is created by sunlight that has passed high through Earth's atmosphere, where
red light is better absorbed by ozone than
blue.
A total eclipse of the Sun will occur this weekend but,
unfortunately, totality be
visible only near the
Earth's South Pole.
APOD: 2021 October 18 - Earthshine Moon over Sicily
Explanation:
Why can we see the entire face of this Moon?
When the
Moon is in a crescent phase,
only part of it appears directly illuminated by the
Sun.
The answer is earthshine,
also known as
earthlight and the
da Vinci glow.
The reason is that the rest of the
Earth-facing Moon
is slightly illuminated by sunlight first reflected from the Earth.
Since the Earth appears near full phase from the
Moon -- when the
Moon appears as a slight crescent
from the Earth --
earthshine is then near its brightest.
Featured here in combined, consecutively-taken,
HDR images
taken earlier this month, a
rising earthshine Moon
was captured passing slowly near the
planet Venus,
the brightest spot near the image center.
Just above Venus is the star
Dschubba (catalogued as
Delta Scorpii),
while the red star on the far left is
Antares.
The
celestial show is visible through scenic cloud decks.
In the foreground are the lights from
Palazzolo Acreide, a
city with ancient
historical roots in
Sicily,
Italy.
APOD: 2021 October 10 - Full Moon Silhouettes
Explanation:
Have you ever watched the Moon rise?
The slow rise of a nearly full moon over a clear horizon can be an impressive sight.
One impressive moonrise was imaged in early 2013 over
Mount Victoria
Lookout in
Wellington,
New Zealand.
With detailed planning, an
industrious astrophotographer
placed a camera about two kilometers away and pointed it across the lookout to where
the Moon
would surely soon be making its nightly debut.
The
featured single shot sequence is unedited and
shown in real time -- it is not a time lapse.
People on
Mount Victoria Lookout
can be seen in silhouette
themselves admiring the dawn of Earth's largest satellite.
Seeing a moonrise yourself is not difficult:
it happens every day, although only half the time at night.
Each day the
Moon rises about
fifty minutes later
than the previous day, with a full moon
always rising at sunset.
This Saturday, October 16, is
International Observe the Moon Night,
where you observe a
first-quarter Moon along with
other lunar enthusiasts.
APOD: 2021 September 23 - Harvest Moon Trail
Explanation:
Famed in festival, story, and song the best known
full moon is the Harvest Moon.
For northern hemisphere dwellers that's a traditional name of the
full moon nearest the September equinox.
Seen from Saunderstown,
Rhode Island, planet Earth, this
Harvest Moon left a broad streak of warm hues as it rose through a twilight
sky over the Newport Bridge.
On September 20 its trail was captured in a single 22 minute exposure
using a dense filter and a digital camera.
Only two days later the September equinox
marked a change of season and the beginning of autumn in the north.
In fact, recognizing a season as the time
between solstice and equinox,
this Harvest Moon was the
fourth full moon of the season,
coming just before the astronomical end of northern summer.
APOD: 2021 August 31 - A Blue Moon in Exaggerated Colors
Explanation:
The Moon is normally seen in subtle shades of grey or
gold.
But small, measurable
color differences have been
greatly exaggerated to make this telescopic, multicolored,
moonscape captured during the Moon's full phase.
The different colors are recognized to correspond to
real differences in the chemical makeup of the
lunar surface.
Blue hues reveal
titanium rich areas while orange and purple colors
show regions relatively poor in titanium and iron.
The familiar
Sea of Tranquility, or
Mare Tranquillitatis, is the blue area toward the upper right.
White lines radiate across the orange-hued southern
lunar highlands from 85-kilometer wide
ray-crater Tycho at bottom right.
The full moon that occurred earlier this month could be counted as a
seasonal blue moon because it was, unusually, the
third of four full moons
to occur during northern summer (and hence southern winter).
The featured 272-image composite demonstrates that the
full Moon is always blue, but usually not blue enough in hue to
ooh.
APOD: 2021 August 26 - A Blue Hour Full Moon
Explanation:
Nature photographers and other fans of planet Earth
always look forward to
the blue
hour.
That's the transition
in twilight,
just before sunrise or after sunset, when
the Sun is below the horizon but land and sky are still suffused with
a beautiful blue light.
After sunset on August 21,
this blue hour snapshot captured the nearly full Moon as it
rose opposite the Sun, above the rugged Italian Alps from
Cortina d'Ampezzo, Italy.
Sharing bluish hues with the sky, the rocky pyramid of Monte Antelao,
also known as the King of the Dolomites,
is the region's prominent alpine peak.
The moonlight
is yellow, but even so this full Moon was known to some
as a seasonal Blue Moon.
That's because by one definition
the third full Moon of a season with four full moons
in it is called a Blue Moon.
Recognizing a season as the time between a solstice and an equinox,
this season's fourth
full Moon will be rising
in the blue hour of September 20, just before September's equinox.
APOD: 2021 July 11 - Find the Moon
Explanation:
Where's the Moon?
Somewhere in this image, the Earth's Moon is hiding.
The entire Moon is visible, in its completely full phase,
in plain sight.
Even the photographer's keen eye couldn't find it even though he knew exactly where to look -- only the
long exposure of his camera picked it up -- barely.
Although by now you might be congratulating yourself on finding it, why was it so difficult to see?
For one reason, this photograph was taken during a
total lunar eclipse, when the Earth's
shadow made
the Moon much dimmer than a normal full Moon.
For another, the image, taken in
Colorado,
USA,
was captured just before sunrise.
With the Moon
on the exact opposite side of the sky from the Sun,
this meant that the Sun was just below the horizon, but still
slightly illuminating
the sky.
Last, as the
Moon was only about two degrees above the horizon, the
large volume of air between the camera and the horizon scattered a lot of light away from the
background Moon.
Twelve minutes after this image was acquired in 2012,
the Sun peeked over the horizon and the Moon set.
APOD: 2021 June 9 - A Total Lunar Eclipse Corona
Explanation:
This moon appears multiply strange.
This moon was a full moon, specifically called a
Flower Moon at this time of the year.
But that didn't make it strange -- full moons occur once a month
(moon-th).
This moon was a
supermoon,
meaning that it reached its full phase near its closest approach to the Earth in its slightly
elliptical orbit.
Somewhat strange, a supermoon appears a bit larger and brighter than the average full moon --
and enables it to be called a Super Flower Moon.Â
This moon was undergoing a
total lunar eclipse.
An eclipsed moon can look
quite strange, being dark,
unevenly lit, and, frequently, red -- sometimes called blood red.
Therefore, this moon could be called a Super Flower Blood Moon.
This moon was seen through thin clouds.
These clouds created a
faint corona
around the moon, making it look not only strange, but
colorful.
This moon was imaged so deeply that the
heart of the
Milky Way galaxy, far in the background, was visible to its lower right.
This moon, this shadow, this galaxy and these colors were all
captured last month near
Cassilis,
NSW,
Australia -- with a single shot. (Merged later with two lower shots that better capture the Milky Way.)
APOD: 2021 May 25 - The Moon During a Total Lunar Eclipse
Explanation:
How does the Moon's appearance change during a total lunar eclipse?
The featured time-lapse video was digitally processed to keep
the Moon bright and centered during the 5-hour
eclipse of 2018 January 31.
At first the
full moon is visible because
only a full moon can undergo a
lunar eclipse.
Stars move by in the background because the Moon orbits
the Earth during
the eclipse.
The circular shadow
of the Earth is then seen moving across the Moon.
The light blue hue of the shadow's edge is related to
why Earth's sky is blue, while the deep red hue of
the shadow's center is related to
why the Sun appears red when near the horizon.
Tomorrow, people living from southeast Asia, across
the Pacific,
to the southwest Americas may
get to see
a Blood Supermoon
Total Lunar Eclipse.
Here the term blood refers to the (likely) red
color of the fully eclipsed Moon,
while the term
supermoon indicates the Moon's slightly high angular size --
due to being relatively close to the Earth in its
slightly elliptical orbit.
APOD: 2021 April 30 - Pink and the Perigee Moon
Explanation:
On April 25 a nearly full moon rose just before sunset.
Welcomed in a clear blue sky and framed by cherry blossoms,
its familiar face was captured in this snapshot
from Leith, Edinburgh, Scotland.
Known to some as a Pink Moon,
April's
full lunar phase
occurred with the moon near perigee.
That's the closest point in its
not-quite-circular
orbit around planet Earth,
making this Pink Moon one of the closest and brightest full moons
of the year.
If you missed it, don't worry.
Your next chance to see a full perigee moon will be on May 26.
Known to some as a
Flower Moon,
May's full moon will actually be
closer to you
than April's by about 98 miles (158 kilometers),
or about 0.04% the distance from the Earth to the Moon at perigee.
APOD: 2021 February 3 - Found on the Moon: Candidate for Oldest Known Earth Rock
Explanation:
Was the oldest known rock on Earth found on the Moon?
Quite possibly.
The story opens with the
Apollo 14 lunar mission.
Lunar sample
14321, a large rock found in
Cone crater by astronaut
Alan Shepard, when analyzed back on Earth,
was found to have a fragment that was a much
better match to Earth rocks than other Moon rocks.
Even more surprising,
that rock section has recently been dated back
4 billion years,
making it older, to within measurement uncertainty, than
any rock ever found on Earth.
A leading hypothesis now holds that an ancient comet or
asteroid impact launched
Earth rocks into the Solar System, some of which fell back to
the Moon,
became mixed with heated lunar soil and other rocks, cooled, and re-fragmented.
The video features an internal
X-ray scan of
14321
showing multiple sections with markedly different chemistries.
Moon rocks
will continue to be
studied to learn a more complete history of the
Moon,
the Earth, and the
early Solar System.
Friday marks the
50th Anniversary of the
Apollo 14
landing on the Moon.
APOD: 2021 January 11 - Moon Phases in 2021
Explanation:
What will the Moon phase be on your birthday this year?
It is
hard to predict because the
Moon's appearance changes nightly.
As the
Moon orbits the
Earth,
the half illuminated by the
Sun
first becomes increasingly visible, then decreasingly visible.
The featured video animates images taken by NASA's Moon-orbiting
Lunar Reconnaissance Orbiter to show all
12 lunations that appear this year, 2021.
A single
lunation
describes one full cycle of our Moon, including all of its
phases.
A full
lunation takes about 29.5 days, just under a month
(moon-th).
As each
lunation progresses, sunlight reflects from the
Moon at different angles, and so
illuminates different features differently.
During all of this, of course,
the Moon
always keeps the same face toward the
Earth.
What is less apparent night-to-night is that
the Moon's apparent size changes slightly,
and that a slight wobble called a
libration occurs as the
Moon progresses along its elliptical orbit.
APOD: 2020 November 11 - Colors of the Moon
Explanation:
What color is the Moon?
It depends on the night.
Outside of the Earth's atmosphere, the
dark Moon,
which shines by reflected sunlight, appears a
magnificently brown-tinged gray.
Viewed from inside the
Earth's atmosphere, though, the moon can appear quite different.
The featured image highlights a collection of apparent colors of the full moon documented by one astrophotographer over 10 years from
different locations across
Italy.
A
red or yellow colored moon usually indicates a moon seen near the horizon.
There, some of the
blue light has been scattered away
by a long path through the
Earth's atmosphere,
sometimes laden with fine dust.
A blue-colored moon is more rare and
can indicate a moon seen through an atmosphere carrying larger dust particles.
What created the purple moon is
unclear --
it may be a combination of several effects.
The last image captures the
total lunar eclipse of 2018 July --
where the moon,
in Earth's shadow, appeared a
faint red -- due to light
refracted through
air around the
Earth.
The next full moon will occur at the end of this month
(moon-th)
and is known in some cultures as the
Beaver Moon.
APOD: 2020 October 2 - Biking to the Moon
Explanation:
As you watched October's
first Full Moon rise last night, the Full Moon
closest to the northern autumnal equinox, you were
probably asking yourself,
"How long would it take to bike to the Moon?"
Sure, Apollo 11 astronauts made the trip in 1969, from launch to
Moon landing,
in about 103 hours or 4.3 days.
But the Moon is 400,000 kilometers away.
This year, the top bike riders in planet Earth's well-known
Tour de France
race covered almost 3,500 kilometers in 21 stages after about
87 hours on the road.
That gives an average speed of about 40 kilometers per hour and a lunar
cycling travel time of 10,000 hours, a little over 416 days.
While this bike rider's
destination isn't clear, his journey did begin
around moonrise on September 27 near Cleeve Hill, Bishops Cleeve,
Cheltenham, UK.
APOD: 2020 September 26 - Moon Pairs and the Synodic Month
Explanation:
Observe the Moon each night and
its visible sunlit portion will gradually change.
In phases progressing
from New Moon to Full Moon to New Moon again, a lunar cycle or
synodic month
is completed in about 29.5 days.
They look full, but top left to bottom right these panels do
show the range of lunar phases for a complete
synodic month during August 2019
from Ragusa, Sicily, Italy, planet Earth.
For this lunar cycle project the panels organize
images of the lunar phases in pairs.
Each individual image is paired with another image separated by
about 15 days, or approximately half a synodic month.
As a result the opposite sunlit portions complete the
lunar disk and the shadow line at the boundary of lunar night and day, the
terminator, steadily marches across the Moon's
familiar nearside.
For extra credit, what lunar phase would you pair with the Moon tonight?
APOD: 2020 September 14 - Corn Moon Rising
Explanation:
A rising moon can be a dramatic sight.
A rising
Full Corn Moon
was captured early this month in time-lapse with a telephoto lens
from nearly 30 kilometers away -- making
Earth's ascending half-degree companion
appear unusually impressive.
The image was captured from
Portugal,
although much of the foreground -- including lights from the village of
Puebla de Guzmán
-- is in
Spain.
A Full Corn Moon is the name
attributed to a full moon at this time of year by cultures of some northern
indigenous peoples of the Americas, as it coincides with the ripening of
corn.
Note that the Moon
does not appear larger when it is nearer the horizon -- its
seemingly larger size there is only an
illusion.
The next full moon -- occurring at the beginning of next month -- will be known as the Full
Harvest Moon as it occurs nearest in time to the
northern autumnal equinox
and the northern field harvests.
APOD: 2020 July 19 - Rotating Moon from LRO
Explanation:
No one, presently, sees the Moon rotate like this.
That's because the Earth's moon is tidally locked to the Earth, showing us
only one side.
Given modern digital technology, however, combined with many detailed images returned by the
Lunar Reconnaissance Orbiter (LRO), a high resolution virtual
Moon rotation movie has been composed.
The featured time-lapse video
starts with the standard Earth
view of the Moon.
Quickly, though,
Mare Orientale, a large crater with a dark center
that is difficult to see from the Earth, rotates into view just below the equator.
From an entire
lunar month condensed into 24 seconds,
the video clearly shows that the Earth side of
the Moon contains an abundance of
dark lunar maria,
while the lunar far side is dominated by bright
lunar highlands.
Currently, over 19 new missions to the Moon are under active development from eight different countries, most of which have expected launch dates in the next three years.
APOD: 2020 June 22 - Moon Mountains Magnified during Ring of Fire Eclipse
Explanation:
What are those dark streaks in this composite image of yesterday's solar eclipse?
They are reversed shadows of mountains at the edge of the Moon.
The center image, captured from
Xiamen,
China,
has the Moon's center directly in front of the Sun's center.
The Moon, though, was
too far from
the Earth to completely block the entire Sun.
Light that streamed around all of the edges of the Moon is called a
ring of fire.
Images at each end of the sequence show
sunlight that streamed through lunar valleys.
As the Moon moved further in front of the Sun, left to right,
only the higher peaks on the Moon's perimeter could block sunlight.
Therefore, the dark streaks are projected, distorted, reversed,
and magnified
shadows of mountains at the Moon's edge.
Bright areas are called
Baily's Beads.
Only a narrow swath across Earth's
Eastern Hemisphere
was able to see yesterday's full annular solar eclipse.
Next June, though, a narrow swath across Earth's
Northern Hemisphere
will be able to see the
next annular solar eclipse.
A total solar eclipse
will be
visible at the
bottom of the world near the end of this year.
APOD: 2020 June 21 - Moon Occults Venus
Explanation:
It may look like
Earthrise, but it's actually Venus-set.
Just after sunrise two days ago, both the Moon and Venus also
rose.
But then the Moon overtook
Venus.
In the
featured image sequence
centered on the Moon, Venus is shown increasingly angularly
close to the Moon.
In the
famous Earthrise image taken just over 50 years ago,
the Earth was captured rising over the edge of the Moon, as seen from the
Apollo 8
crew orbiting the Moon.
This similar Venus-set image was taken from Earth, of course, specifically
Estonia.
Venus shows only a thin crescent because last week it passed
nearly in front of the Sun, as seen from Earth.
The Moon shows only a
thin crescent
because it will soon be passing directly in front of the
Sun, as seen from Earth.
Today, in fact, two days after this image was taken, the Moon
will create a solar eclipse, with a thin swath across the Earth treated to an
annular solar eclipse.
APOD: 2020 May 7 - Analemma of the Moon
Explanation:
An analemma
is that figure-8 curve you get when you mark
the position of the Sun at the same
time each day for one year.
But the trick to imaging an
analemma of the Moon is to wait bit
longer.
On average the
Moon returns
to the same position in the sky
about 50 minutes and 29 seconds later each day.
So photograph the Moon 50 minutes 29 seconds
later on successive days.
Over one lunation or lunar month it will trace out an analemma-like curve
as the Moon's actual position wanders due to
its tilted and elliptical orbit.
To create this composite image of a lunar analemma,
astronomer Gyorgy Soponyai chose a lunar month
from March 26 to April 18 with a good stretch of weather
and a site close to home near Mogyorod, Hungary.
Crescent lunar phases too thin and faint to capture
around the New Moon are missing though.
Facing southwest, the lights of
Budapest
are in the distance of the base image taken on March 27.
APOD: 2020 April 10 - Full Moon of Spring
Explanation:
From home this Full Moon
looked bright.
Around our fair planet it rose as the Sun set on April 7/8, the first
Full Moon after the
vernal equinox and
the start of northern hemisphere spring.
April's
full lunar phase was
also near perigee,
the closest point in the Moon's elliptical orbit.
In fact, it was nearer perigee than any other Full Moon of 2020
making it the
brightest Full Moon
of the year.
To create the visual experience a range of
exposures was blended to capture the emerging
foreground foliage
and bright lunar disk.
The hopefull image of spring was recorded from a home garden
in skies over Chongqing, China.
APOD: 2020 March 22 - Moon Setting Behind Teide Volcano
Explanation:
These people are not in danger.
What is coming down from the left is just the Moon, far in the distance.
Luna appears so large here because she is being
photographed through a telescopic lens.
What is moving is mostly
the Earth, whose spin causes
the Moon to slowly disappear behind
Mount Teide,
a volcano in the
Canary Islands
off the northwest coast of
Africa.
The people pictured are
16 kilometers away and
many are facing the camera because they are watching
the Sun rise behind the photographer.
It is not a
coincidence that a
full moon rises just when the
Sun sets because the Sun is always on the
opposite side of the sky from a full moon.
The featured video
was made two years ago during the full
Milk Moon.
The video is not time-lapse --
this was really how fast
the Moon was setting.
APOD: 2020 March 3 - Apollo 13 Views of the Moon
Explanation:
What if the only way to get back to Earth was to go around the far side of the Moon?
Such was the dilemma of the
Apollo 13 Crew in 1970 as they tried to
return home in their unexpectedly
damaged spacecraft.
With the Moon in the middle, their
perilous journey
substituted spectacular views of the
lunar farside for radio contact with NASA's
Mission Control.
These views have now been
digitally recreated
from detailed images of the
Moon taken by the robotic
Lunar Reconnaissance Orbiter.
The featured video starts by showing Earth disappear behind a dark lunar limb,
while eight minutes later the
Sun
rises around the opposite side of the Moon and
begins to illuminate the Moon's unusual and
spectacularly cratered surface.
Radio contact was only re-established several minutes after that, as a crescent
Earth rose into view.
With the gravity of the Moon and the advice of many industrious
NASA engineers and scientists,
a few days later
Apollo 13 opened its parachutes over the
Pacific Ocean and
landed safely back on
Earth.
APOD: 2020 February 24 - Moon Corona, Halo, and Arcs over Manitoba
Explanation:
Yes, but could you get to work on time if the Moon looked like this?
As the photographer was preparing to drive to work,
refraction,
reflection, and even
diffraction of moonlight from millions of falling ice crystals turned the
familiar icon of our Moon into a
menagerie of other-worldly halos and arcs.
The featured scene was captured with
three combined exposures two weeks ago on a cold winter morning in
Manitoba,
Canada.
The colorful rings
are a corona caused by
quantum diffraction
by small drops of water or ice near the direction of the
Moon.
Outside of that, a
22-degree halo
was created by moonlight refracting through six-sided cylindrical
ice crystals.
To the sides are
moon dogs, caused by light refracting through thin, flat,
six-sided ice platelets
as they flittered toward the ground.
Visible at the top and bottom of the
22-degree halo are upper and lower
tangent arcs,
created by moonlight refracting through nearly horizontal
hexagonal ice cylinders.
A few minutes later, from a field just off the road to work,
the halo and arcs had disappeared, the sky had returned to normal --
with the exception of a
single faint moon dog.
APOD: 2019 September 13 - A Harvest Moon
Explanation:
Famed in festival, story, and song the best known full moon is
the
Harvest Moon.
For northern hemisphere dwellers that's a traditional name of the
full moon nearest the September equinox.
In most North America time zones
this
year's Harvest Moon
will officially rise on Friday, September 13.
In fact the same Harvest Moon will rise on September 14
for much of the planet though.
Of course the Moon will look almost full in the surrounding days.
Regardless of your time zone the Harvest Moon,
like any other full moon, will rise just opposite the setting Sun.
Near the horizon, the
Moon
Illusion might make it
appear bigger and brighter to you
but this Harvest Moon will be near
lunar apogee.
That's the farthest point in its orbit, making it the most distant,
and so the smallest, full moon of the year.
On August 15 a wheat field harvested in south central France
made this
a harvest moon
scene too, the
full
moon shining on
with beautiful iridescent clouds at sunset.
APOD: 2019 August 14 - Saturn Behind the Moon
Explanation:
What's that next to the Moon?
Saturn.
In its monthly trip around the
Earth -- and hence Earth's sky -- our Moon passed nearly in front of
Sun-orbiting Saturn earlier this week.
Actually the
Moon passed directly in front of
Saturn from the viewpoints of a wide swath of Earth's
Southern Hemisphere.
The
featured image from
Sydney,
Australia
captured the pair a few minutes before the
eclipse.
The image was a single shot lasting only 1/500th of a second,
later processed to better highlight both the
Moon and Saturn.
Since
Saturn is nearly opposite the Sun,
it can be seen nearly the entire night, starting at sunset,
toward the south and east.
The
gibbous Moon was also nearly opposite the Sun,
and so also visible nearly the entire night -- it will be
full tomorrow night.
The
Moon will occult Saturn again
during every lap it makes around the Earth this year.
APOD: 2019 July 22 - HDR: Earths Circular Shadow on the Moon
Explanation:
What could create such a large circular shadow on the Moon?
The Earth.
Last week's full Moon -- the
Buck Moon -- was so full that it fell almost exactly
in a line with the
Sun and the
Earth.
When that happens the Earth casts its
shadow onto the Moon.
The circularity of the Earth's shadow on the Moon was commented on by
Aristotle and so has
been noticed since at least the
4th century BC.
What's new is humanity's ability to record
this shadow with such
high dynamic range (HDR).
The featured HDR composite of last week's partial
lunar eclipse
combines 15 images and include an exposure as short as 1/400th of a second --
so as not to overexpose the brightest part --
and an exposure that lasted five seconds --
to bring up the dimmest part.
This dimmest part -- inside
Earth's umbra -- is
not completely dark
because some
light is refracted through the
Earth's atmosphere
onto the Moon.
A total lunar eclipse will
occur next in 2021 May.
APOD: 2019 July 16 - Apollo 11 Launches Humans to the Moon
Explanation:
Everybody saw the Moon. Nobody had ever been there.
Humans across planet Earth watched in awe 50 years ago today as a powerful
Saturn V rocket attempted to launch humans -- to
the Moon.
Some in space flight guessed that the machinery was so complex, that so many things had to go right for it to work, that
Apollo 11 would end up being
another
useful dress rehearsal for a later successful Moon-landing mission.
But to the Moon they went.
The featured video starts by showing astronauts
Aldrin,
Armstrong, and
Collins
making their way to the waiting rocket.
As the large and
mighty
Saturn V launched, crowds watched from
Cape Canaveral in
Florida,
USA
and on television around the world.
The events that unfolded over the next few days, including a dramatic
moon walk
50 years ago this Saturday, will forever be remembered as a milestone in
human history and an unrivaled demonstration of human ingenuity.
This week, many places around the world are planning
celebrations of the
50th anniversary of the first humans landing
on the Moon.
APOD: 2019 June 18 - Strawberry Moon over the Temple of Poseidon
Explanation:
Did you see the full moon last night?
If not, tonight's nearly
full moon should be almost as good.
Because
full moons
are
opposite the Sun,
they are
visible in the sky when
the Sun
is not -- which should be nearly all night long tonight, clouds permitting.
One nickname for
June's full moon is the
Strawberry Moon, named for when wild
strawberries start to ripen in parts of
Earth's northern hemisphere.
Different cultures around the globe give this full
moon different
names,
though, including Honey Moon and Rose Moon.
In the foreground of this featured image, taken yesterday in
Cape Sounion,
Greece,
is the 2,400 year-old
Temple of Poseidon.
Next month will the
50th anniversary of the time humans first landed on the Moon.
APOD: 2019 February 12 - Plane Crossing a Crescent Moon
Explanation:
No, this is not a good way to
get to the Moon.
What is pictured is a chance superposition of an airplane and the Moon.
The contrail would normally appear white,
but the large volume of air toward the setting Sun preferentially
knocks away blue light, giving the reflected
trail a bright red hue.
Far in the distance, well behind the plane, is a
crescent Moon, also slightly reddened.
Captured a month ago above
Valais,
Switzerland,
the featured image was taken so soon after sunset that planes
in the sky were still in sunlight, as were their
contrails.
Within minutes, unfortunately, the impromptu sky show ended.
The plane crossed
the Moon and moved out of sight.
The Moon set.
The contrail became unilluminated and then dispersed.
APOD: 2019 February 6 - Moon and Venus Appulse over a Tree
Explanation:
What's that bright spot near the Moon?
Venus.
About a week ago,
Earth's Moon appeared
unusually close to the distant planet Venus,
an angular coincidence known as an
appulse.
Similar to a
conjunction, which is a
coordinate term, an appulse refers more generally to when two celestial objects appear close together.
This Moon and Venus appulse -- once as close as 0.05 degrees -- was
captured
rising during the early morning behind
Koko
crater on the island of
O'ahu in
Hawaii,
USA.
The Moon was in a crescent phase with its lower left reflecting direct sunlight,
while the rest of the Moon is seen because of
Earthshine, sunlight first reflected from the Earth.
Some leaves and branches of a foreground
kiawe
tree are seen in silhouette in front of the bright crescent, while others,
in front of a darker background, appear white because of
forward scattering.
Appulses involving the Moon typically occur
several times a year: for example the Moon is expected
to pass within 0.20
degrees of distant Saturn on March 1.
APOD: 2018 November 19 - Gibbous Moon beyond Swedish Mountain
Explanation:
This is a gibbous Moon.
More Earthlings
are familiar with a full moon, when the entire face of
Luna is lit by the
Sun, and a crescent moon,
when only a sliver of the
Moon's face is lit.
When more than half of the Moon is illuminated, though,
but still short of full illumination, the
phase
is called gibbous.
Rarely seen in television and movies,
gibbous moons
are quite common in the actual night sky.
The featured image was taken in
Jämtland,
Sweden
near the end of last month.
That gibbous moon turned, in a few days, into a crescent moon, and then a
new moon,
then back to a crescent, and a few days ago back to gibbous.
And this same
gibbous moon is visible again tonight,
leading up to the Full
Beaver Moon that occurs Friday night.
Setting up to capture a picturesque gibbous moonscape, the photographer was
quite surprised to find an airplane,
surely well in the foreground,
appearing to fly past it.
APOD: 2018 November 10 - The Old Moon in the Young Moon's Arms
Explanation:
Tonight the Moon is
young again,
but this stunning image of a young Moon near the western horizon
was taken just after sunset on October 10.
On the lunar disk
Earthshine, earthlight
reflected from the Moon's night side,
is embraced by
the slim, sunlit crescent just over 2 days old.
Along the horizon fading colors of twilight silhouette
the radio telescope dish antennas of the
Very Large Array,
New Mexico, planet Earth.
The view from the Moon would be stunning, too.
When the Moon appears in Earth's sky as a slender crescent,
a dazzlingly bright, nearly full Earth would be seen
from the lunar surface.
A description of earthshine, in terms of sunlight
reflected by Earth's oceans in turn illuminating
the Moon's dark surface, was written 500 years ago by
Leonardo da Vinci.
APOD: 2018 September 4 - Moon behind Lava Fountain
Explanation:
What's happened to the Moon?
Nothing, but something has happened to the image of the Moon.
The heat from a
volcanic lava fountain in the foreground has warmed and made
turbulent
the air nearby, causing passing light to
refract differently than usual.
The result is a
lava plume that appears to be
melting the Moon.
The featured picture was taken as the full
Sturgeon Moon was
setting behind
Mt. Etna as it
erupted in
Italy about one week ago.
The picture is actually a
composite of two images,
one taken right after the other, with the same camera and lens.
The
first image
was a quick exposure to capture details of the setting Moon, while the
second exposure,
taken after the Moon set a few minutes later,
was longer so as to capture details of the faint lava jets.
From our Earth, we can only see the
Sun,
Moon, planets, and stars as they appear through the distortion of the
Earth's atmosphere.
This distortion can not only change the images of familiar orbs into
unusual
shapes, it can --unexpectedly at times --
delay sunset
and moonset by several minutes.
APOD: 2018 July 17 - Moon and Venus over Cannon Beach
Explanation:
What's that spot next to the Moon?
Venus.
Two days ago, the crescent Moon slowly drifted past Venus, appearing
within just one degree at its closest.
This conjunction, though, was just one of several
photographic adventures for our Moon this month
(moon-th),
because, for one, a partial solar eclipse occurred
just a few days before, on July 12.
Currently, the Moon appears to be brightening, as seen from the Earth, as the fraction of its face illuminated by the Sun continues to increase.
In a few days,
the Moon
will appear more than half full, and therefore be in its
gibbous phase.
Next week the face of
the Moon
that always faces
the Earth will become, as viewed from the Earth, completely illuminated by
the Sun.
Even this full phase will bring an adventure, though, as a total eclipse of this
Thunder Moon will occur on July 27.
Don't worry about
our Luna getting tired, though, because she'll be new again next month (moon-th) -- August 11 to be exact -- just as she causes another partial eclipse of the Sun.
Pictured,
Venus and the Moon were captured from
Cannon Beach above a rock formation off the
Oregon
(USA)
coast known as the Needles.
About an hour after this image was taken,
the spin of the Earth caused both
Venus and the Moon to
set.
APOD: 2018 June 30 - The East 96th Street Moon
Explanation:
A very full Moon
rose over Manhattan's Upper Eastside on June 28,
known to some as the
Strawberry Moon.
Near the horizon, the warm yellow lunar disk was a bit ruffled and
dimmed by a long sight-line through dense, hazy atmosphere.
Still it fit well with traffic and lights along East 96th street
in this urban astroimage.
The telephoto shot was (safely) taken from elevated ground
looking east-southeast from Central Park,
planet
Earth.
Of course, the East 96th street moon was the closest Full Moon to
this year's northern summer solstice.
APOD: 2018 June 24 - Rocket Plume Shadow Points to the Moon
Explanation:
Why would the shadow of a
space shuttle
launch plume point toward the Moon?
In early 2001 during a launch of
Atlantis,
the Sun,
Earth,
Moon,
and rocket were all properly aligned for
this photogenic coincidence.
First, for the
space shuttle's plume to cast a long shadow,
the time of day must be either near
sunrise or
sunset.
Only then will the
shadow
be its longest and extend all the way to the
horizon.
Finally, during a
Full Moon, the
Sun and
Moon are on
opposite sides of the sky.
Just after
sunset, for example, the Sun is slightly below the
horizon, and,
in the other direction, the Moon is slightly above the horizon.
Therefore, as
Atlantis blasted off, just after
sunset,
its shadow projected away from the Sun
toward the opposite horizon, where the
Full Moon happened to be.
APOD: 2018 June 4 - Moon Setting Behind Teide Volcano
Explanation:
These people are not in danger.
What is coming down from the left is just the Moon, far in the distance.
Luna appears so large here because she is being
photographed through a telescopic lens.
What is moving is mostly
the Earth, whose spin causes
the Moon to slowly disappear behind
Mount Teide,
a volcano in the
Canary Islands
off the northwest coast of
Africa.
The people pictured are
16 kilometers away and
many are facing the camera because they are watching
the Sun rise behind the photographer.
It is not a
coincidence that a
full moon rises just when the
Sun sets because the Sun is always on the
opposite side of the sky from a full moon.
The featured video
was made last week during the full
Milk Moon.
The video is not time-lapse --
this was really how fast the Moon was setting.
APOD: 2018 March 28 - Blue Moon Tree
Explanation:
Does an alignment like this occur only once in a blue moon?
No, although it was during a
blue moon that this single-shot image was taken.
During a full
moon that happened to be the second of the month --
the situation that defines a
blue moon --
the photographer created the juxtaposition in late January by quickly moving around to find just the right spot to get the
background Moon
superposed behind the arc of a
foreground tree.
Unfortunately, in this case, there seemed no other way than getting bogged down in mud and resting the camera on a barbed-wire fence.
The arc in the oak tree was previously created by hungry cows in
Knight's Ferry,
California,
USA.
Quirky
Moon-tree juxtapositions
like this can be created during any
full moon though, given enough
planning and time.
Another opportunity will arise this weekend, coincidently during another
blue moon.
Then, the second blue moon in 2018 will occur, meaning that for the second month this year, two full moons will appear during a single month (moon-th).
Double blue-moon years are
relatively rare, with the last occurring in 1999, and the next in 2037.
APOD: 2018 March 18 - Rotating Moon from LRO
Explanation:
No one, presently, sees the Moon rotate like this.
That's because the Earth's moon is tidally locked to the Earth, showing us
only one side.
Given modern digital technology, however, combined with many detailed images returned by the
Lunar Reconnaissance Orbiter (LRO), a high resolution virtual
Moon rotation movie has been composed.
The above time-lapse video
starts with the standard Earth
view of the Moon.
Quickly, though,
Mare Orientale, a large crater with a dark center
that is difficult to see from the Earth, rotates into view just below the equator.
From an entire
lunar month condensed into 24 seconds,
the video clearly shows that the Earth side of
the Moon contains an abundance of
dark lunar maria,
while the lunar far side is dominated by bright
lunar highlands.
Currently, over 20 new missions to the Moon are under active development from four different countries, most of which have expected launch dates either this year or next.
APOD: 2018 March 10 - Phases of the Moon
Explanation:
Look at the Moon
every night and its visible sunlit portion gradually changes.
In phases progressing
from New Moon to Full Moon to New Moon again,
a lunar cycle or lunation is completed in about 29.5 days.
Top left to bottom right, these frames show the range of
lunar phases for 25 consecutive nights beginning on January 18,
following an
almost
complete lunation.
They skip the 2 days just after and 2 days before
New Moon,
when the lunar phase is at best a narrow crescent, close to the Sun
and really hard to see.
Of course, mostly clear Arizona night skies and a little help from
a friend were required to complete this lunar cycle project,
imaging in early evening for the first half and
late evening and early morning for the second half of the lunation.
For extra credit, the cycle was centered on the Full Moon of January 31.
That was the second Full Moon in January, when the Moon was near lunar
orbit perigee and took on reddish hues during a
total lunar eclipse.
APOD: 2018 January 20 - Old Moon in the New Moon's Arms
Explanation:
Also known as the Moon's "ashen glow" or the "Old Moon in the
New Moon's arms",
earthshine
is earthlight reflected from the Moon's night side.
This stunning image of earthshine from a young crescent moon
was taken from Las Campanas Observatory, Atacama Desert, Chile,
planet Earth
near moonset on January 18.
Dramatic atmospheric inversion
layers appear above the Pacific
Ocean, colored by the sunset at the planet's western horizon.
But the view from the Moon would have been stunning, too.
When the Moon appears in Earth's sky as a slender crescent,
a dazzlingly bright, nearly full Earth would be seen
from the lunar surface.
A description of earthshine, in terms of sunlight
reflected by Earth's oceans in turn illuminating
the Moon's dark surface, was written 500 years ago by
Leonardo da Vinci.
APOD: 2017 December 3 - Full Moon Silhouettes
Explanation:
Have you ever watched the Moon rise?
The slow rise of a nearly full moon over a clear horizon can be an impressive sight.
One impressive moonrise was imaged in early 2013 over
Mount Victoria Lookout in
Wellington,
New Zealand.
With detailed planning, an
industrious astrophotographer
placed a camera about two kilometers away and pointed it across the lookout to where
the Moon
would surely soon be making its nightly debut.
The
featured single shot sequence is unedited and
shown in real time -- it is not a time lapse.
People on
Mount Victoria Lookout
can be seen in silhouette themselves admiring the dawn of Earth's largest satellite.
Seeing a moonrise yourself is not difficult:
it happens every day, although only half the time at night.
Each day the
Moon rises about
fifty minutes later
than the previous day, with a full moon
always rising at sunset.
A good time to see a full moonrise
will occur tonight at sunset as
the Moon's relative closeness to Earth during a full phase -- called a
supermoon -- will cause it to appear slightly larger and brighter than usual.
APOD: 2017 October 25 - Marius Hills: Holes in the Moon
Explanation:
Could humans live beneath the surface of the Moon?
This intriguing possibility was bolstered in 2009 when Japan's Moon-orbiting
SELENE spacecraft imaged a curious hole beneath the Marius Hills region on the Moon, possibly a
skylight
to an underground lava tube.
Follow-up observations by NASA's
Lunar Reconnaissance Orbiter (LRO) indicated that the
Marius Hills Hole (MHH)
visually extends down nearly 100 meters and is several hundred meters wide.
Most recently, ground penetrating radar
data from SELENE has been
re-analyzed to reveal a series of intriguing second echoes --
indicators that the extensive
lava tubes exist under Marius Hills might extend down even kilometers and be large enough to house cities.
Such tubes could
shelter a future Moon colony
from large temperature swings,
micro-meteor impacts, and
harmful solar radiation.
Potentially,
underground lava tubes might even be sealed to contain
breathable air.
These lava tubes
likely formed when lunar volcanos were active billions of years ago.
Pictured, the surface of
Marius Hills
region was captured in the 1960s by NASA's
Lunar Orbiter
2 mission, while an inset image of the MHH is shown from NASA's continuing LRO.
Several volcanic domes are visible, while
Marius Crater is visible on the upper right.
APOD: 2017 January 17 - Fly Me to the Moon
Explanation:
No, this is not a good way to
get to the Moon.
What is pictured is a chance superposition of an airplane and the Moon.
The contrail would normally appear white,
but the large volume of air toward the setting Sun preferentially
knocks away blue light, giving the reflected
trail a bright red hue.
Far in the distance, to the right of the plane, is the
young Moon.
This vast world
shows only a sliver of itself because the
Sun
is nearly lined up behind it.
Captured two weeks ago,
the featured image was framed by an eerie maroon sky,
too far from day to be blue, too far from night to be black.
Within minutes the
impromptu sky show ended.
The plane crossed the Moon. The contrail dispersed. The Sun set. The Moon set.
The sky faded to black, only to
reveal thousands of stars that had been
too faint to see through the rustic red din.
APOD: 2016 November 13 - Super Moon vs Micro Moon
Explanation:
What is so super about tomorrow's supermoon?
Tomorrow, a full moon will occur that appears slightly larger and brighter than usual.
The reason is that the
Moon's fully illuminated phase occurs within a short time from perigee - when the Moon is its closest to the Earth in its elliptical orbit.
Although the precise conditions that define a
supermoon vary,
tomorrow's supermoon will undoubtedly qualify because it will be the
closest, largest, and brightest full moon in
over 65 years.
One reason
supermoons are popular is because they are so easy to see --
just go outside at sunset and watch an impressive full moon rise!
Since perigee actually occurs tomorrow morning, tonight's
full moon, visible starting at
sunset, should also be impressive.
Pictured here, a
supermoon from 2012 is compared to a micromoon -- when a full Moon occurs near the furthest part of the Moon's orbit -- so that it appears smaller and dimmer than usual.
Given
many definitions, at least one
supermoon
occurs each year, with another one coming next month (moon-th).
However, a full moon will not come this close to Earth again until 2034.
APOD: 2016 October 21 - Full Moon in Mountain Shadow
Explanation:
On October 15, standing near the summit of Hawaii's
Mauna Kea
and looking away from a gorgeous sunset produced this
magnificent snapshot of a Full Moon rising within
the volcanic mountain's shadow.
An alignment across the
Solar System is captured in the
stunning scene and seeming contradiction of bright Moon in dark shadow.
The triangular appearance of a
shadow cast
by a mountain's irregular profile is normal.
It's created by the perspective
of the distant mountaintop view through the dense atmosphere.
Rising as the Sun sets, the antisolar point or
the point opposite the Sun is close to the perspective's vanishing
point near the mountain shadow's peak.
But extending in the antisolar direction, Earth's conical shadow is
only a few lunar diameters
wide at the distance of the Moon.
So October's
Full Hunters Moon is still reflecting sunlight,
seen through the mountain's atmospheric shadow but
found too far from the antisolar point and the Earth's extended shadow
to be eclipsed.
APOD: 2016 October 8 - Moon, Mercury, and Twilight Radio
Explanation:
Sharing
dawn's twilight with the Moon on September 29,
Mercury was about as far from the Sun as it can wander,
the innermost planet close to its maximum elongation in
planet Earth's skies.
In this colorful scene fleeting Mercury is
joined by a waning sunlit lunar crescent and earthlit
lunar nightside,
the New Moon in the Old Moon's arms.
Below is the Italian
Medicina Radio
Astronomical Station near Bologna with a low row of antennae that is
part of Italy's first radio telescope array dubbed the "Northern Cross",
and a 32-meter-diameter parabolic dish.
Of course, moonwatchers won't have to rise in early morning hours
on October 8.
After sunset the Moon will be high and bright in evening skies,
at its first quarter phase for
International Observe
the Moon Night.
APOD: 2016 September 16 - Full Moon over Brno
Explanation:
After sunset
this gorgeous full moon rose over
Brno city in the Czech Republic on July 20, 2016.
The panoramic image was made
during a celebration of the 47th anniversary of the
Apollo 11 lunar landing.
A series of exposures captures the yellow hued lunar disk
against the fading colors of twilight, with
the 14th century Spilberk castle illuminated in the foreground.
Of course, tonight's full moon is called
the
Harvest Moon.
The closest full moon to the northern hemisphere's autumnal equinox,
its traditional name has
long been celebrated in
story
and song.
Tonight's full lunar phase also coincides with a subtle,
penumbral lunar eclipse, the Moon passing only through the
Earth's diffuse, outer shadow.
APOD: 2016 July 10 - Moon Meets Jupiter
Explanation:
What's that next to the Moon?
Jupiter -- and its four largest moons.
Skygazers
around planet Earth enjoyed the close encounter of planets and
Moon in 2012 July 15's predawn skies.
And while many saw bright Jupiter next to the slender, waning crescent,
Europeans also had the opportunity to watch the
ruling gas giant pass
behind the lunar disk, occulted by the Moon as it slid through the
night.
Clouds threaten in this telescopic view from
Montecassiano,
Italy, but
the frame still captures Jupiter after it emerged from the occultation
along with all four of its large Galilean moons.
The sunlit crescent is overexposed with the Moon's night side faintly
illuminated by Earthshine.
Lined up left to right beyond the dark lunar limb are Callisto,
Ganymede, Jupiter, Io, and Europa.
In fact,
Callisto, Ganymede, and Io are larger than Earth's Moon, while
Europa is only slightly smaller.
Last week,
NASA's Juno became the second
spacecraft ever to orbit Jupiter.
APOD: 2016 April 29 - Fermi's Gamma-ray Moon
Explanation:
If you could only see
gamma-rays,
photons with up to a billion
or more times the energy of visible light,
the Moon would be brighter than the Sun!
That startling notion underlies this novel image of the Moon, based
on data collected by the
Fermi Gamma-ray Space
Telescope's
Large Area Telescope (LAT) instrument during its first seven years
of operation (2008-2015).
Fermi's gamma-ray vision doesn't distinguish details on the lunar
surface, but a gamma-ray glow consistent with
the Moon's size and position is clearly found at the center of the
false color map.
The brightest pixels correspond to the most significant detections
of lunar gamma-rays.
Why is the gamma-ray
Moon so bright?
High-energy charged particles streaming through the Solar System
known as cosmic rays
constantly bombard the lunar surface, unprotected by a magnetic field,
generating the gamma-ray glow.
Because the cosmic rays come from all sides, the gamma-ray
Moon is always full and does not go through phases.
The first gamma-ray image
of the Moon was captured by the EGRET instrument onboard the
Compton
Gamma-ray Observatory, launched 25 years ago.
APOD: 2016 February 1 - Find the Man in the Moon
Explanation:
Have you ever seen the Man in the Moon?
This common question plays on the ability of humans to see
pareidolia -- imagining familiar icons where they don't actually exist.
The textured surface of Earth's
full Moon
is home to numerous identifications of iconic objects,
not only in modern western culture but in
world folklore throughout history.
Examples, typically dependent on
the Moon's perceived orientation, include the
Woman in the Moon and the
Rabbit in the Moon.
One facial outline commonly identified as the
Man in the Moon
starts by imagining the two dark circular areas --
lunar maria -- here just above
the Moon's center, to be the eyes.
Surprisingly, there actually is a man in this
Moon image -- a
close look
will reveal a real person -- with a telescope --
silhouetted against the Moon.
This featured well-planned image was taken in mid-January in
Cadalso de los Vidrios in
Madrid,
Spain.
Do you have a
favorite object that you see in the Moon?
APOD: 2015 August 11 - A Blue Moon Halo over Antarctica
Explanation:
Have you ever seen a halo around the Moon?
Such 22 degree rings around the Moon -- caused by
ice crystals
falling in the
Earth's atmosphere -- are
somewhat rare.
OK, but have you ever seen a blue moon?
Given the modern definition of
blue moon -- the second full moon occurring in a calendar month -- these are also rare.
What is featured above might therefore be considered doubly rare -- a
halo surrounding a
blue moon.
The featured image was taken late last month near
Zhongshan Station
in Antarctica.
Visible in the foreground are a power generating house and a
snowmobile.
What might seem to be stars in the background are actually illuminated snowflakes near the camera.
APOD: 2015 August 7 - Full Earth, Full Moon
Explanation:
The Moon was new on July 16.
Its familiar nearside
facing the surface of planet Earth was in shadow.
But on that date
a
million miles away, the
Deep Space Climate Observatory (DSCOVR) spacecraft's Earth
Polychromatic Imaging Camera (EPIC)
captured this view
of an apparently Full Moon crossing in front of a Full Earth.
In fact, seen from the spacecraft's position
beyond the Moon's orbit and between Earth and Sun, the fully
illuminated lunar hemisphere is the less familiar
farside.
Only known since the dawn of the
space age, the farside
is mostly devoid of dark lunar maria that sprawl across the Moon's
perpetual Earth-facing hemisphere.
Only the small dark spot of
the farside's Mare Moscoviense (Sea of Moscow) is clear, at
the upper left.
Planet Earth's north pole is near 11 o'clock, with the North America
visited by Hurricane Dolores near center.
Slight color shifts are visible around the lunar edge, an artifact
of the Moon's motion through the field caused by combining the
camera's separate exposures taken in quick succession through different
color filters.
While monitoring the Earth and solar wind for space weather forcasts,
about twice a year DSCOVR can capture
similar images of Moon and Earth
together as it crosses the orbital plane of the Moon.
APOD: 2015 July 31 - The ISS and a Colorful Moon
Explanation:
Tonight's Full Moon, the second Full Moon in July, could be
called a blue moon
according
to modern folklore.
But this sharp and detailed mosaic, recorded with telescope and
digital camera just before July's first Full Moon,
actually does show a colorful lunar surface.
The colors have been enhanced in the processed image but are
real nonetheless,
corresponding to real differences
in the chemical makeup of the lunar surface.
Also easy to see especially when the Moon is near full phase,
bright rays from 85 kilometer wide Tycho crater at the upper right extend
far across the lunar surface.
Against the southern lunar highlands above and right
of Tycho is an amazingly detailed silhouette of the
International Space Station.
Seen from Byron Bay, NSW Australia on June 30, the ISS lunar transit
lasted about 1/3 of a second,
captured with a fast shutter speed in burst mode.
APOD: 2015 April 3 - Sun and Moon Halo
Explanation:
Two pictures captured on April 1
are combined in this
creative
day
and
night
composite.
Separated in time by about 10 hours the images otherwise match, looking
along the coast at Östersund Sweden.
The relative times were chosen to show the Sun and a nearly full Moon
at the same place in the
cold, early springtime sky.
In the night scene Jupiter also shines above the waterfront lights,
while Sun and Moon are both surrounded by a beautiful circular ice halo.
The Sun and Moon halos really do align, each with an
angular radius of 22 degrees.
That radius is a constant, not determined by the brightness
of Sun or Moon but
only
by the hexagonal geometry of
atmospheric
ice crystals
and the reflection and refraction of light.
Of course tomorrow, April 4, will find the Sun and Moon
on opposite sides of planet Earth for a
total lunar eclipse.
APOD: 2015 January 10 - The Windmill's Moon
Explanation:
Seen from the
Canary
Island
of
Fuerteventura, this bright
Full Moon rose at sunset.
Reaching its full phase
on the night
of January 4/5, it was
the first Full Moon of the new year and the first to follow
December's solstice.
Of course, in North America the first Full Moon of January
has been known as
the Wolf's Moon.
But this Full Moon, posed in the twilight above an island of strong
winds and traditional windmills,
suggests another name.
The
telephoto image, taken at a distance from the foreground
windmill, creates the
dramatic comparison in
apparent size for windmill and Full Moon.
APOD: 2014 September 8 - Super Moon vs Micro Moon
Explanation:
What is so super about tomorrow's supermoon?
Tomorrow, a full moon will occur that appears slightly larger and brighter than usual.
The reason is that the Moon's fully illuminated phase occurs within a short time from perigee - when the Moon is its closest to the Earth in its elliptical orbit.
Although the precise conditions that define a
supermoon vary, given one definition, tomorrow's will be the third supermoon of the year -- and the third consecutive month that a supermoon occurs.
One reason
supermoons are popular is because they are so easy to see --
just go outside and sunset and watch an impressive full moon rise!
Since perigee actually occurs today, tonight's sunset
moonrise should also be impressive.
Pictured above, a
supermoon from 2012 is compared to a micromoon -- when a full Moon occurs near the furthest part of the Moon's orbit -- so that it appears smaller and dimmer than usual.
Given many definitions, at least one
supermoon
occurs each year, with the next being 2015 August 30.
APOD: 2014 September 7 - Full Moon Silhouettes
Explanation:
Have you ever watched the Moon rise?
The slow rise of a nearly full moon over a clear horizon can be an impressive sight.
One impressive moonrise was imaged in early 2013 over
Mount Victoria Lookout in
Wellington,
New Zealand.
With detailed planning, an
industrious astrophotographer
placed a camera about two kilometers away and pointed it across the lookout to where
the Moon
would surely soon be making its nightly debut.
The
above single shot sequence is unedited and
shown in real time -- it is not a time lapse.
People on
Mount Victoria Lookout
can be seen in silhouette themselves admiring the dawn of Earth's largest satellite.
Seeing a moonrise yourself is not difficult:
it happens every day, although only half the time at night.
Each day the
Moon rises about
fifty minutes later
than the previous day, with a full moon
always rising at sunset.
A good time to see a moonrise will occur at sunset on Tuesday as
the Moon's relative closeness to Earth during a full phase -- called a
supermoon -- will cause it to appear slightly larger and brighter than usual.
APOD: 2014 June 21 - Lisbon Honey Moon
Explanation:
The Sun set on
Friday
the 13th as a full Honey Moon rose,
captured in this well-planned time-lapse sequence.
Lisbon, Portugal's Christ the King monument
is in the foreground, about 6 kilometers distant from
camera and telephoto lens.
During the days surrounding today's
solstice (June 21, 10:51 UT) the Sun
follows its highest arc through northern hemisphere skies as it travels
along the ecliptic plane.
At night the ecliptic plane is low, and
the Full Moon's path close to the ecliptic was also low,
the rising Moon separating more slowly from the distant horizon.
Northern moon watchers were likely to experience the mysterious
Moon Illusion,
the lunar orb
appearing impossibly large while near the horizon.
But the photo sequence shows the Moon's
apparent size did not
not change at all.
Its light was initially scattered by the long line-of-sight through
the atmosphere though, and a deeper reddened color
gave way to a paler gold as the Full Moon rose
into the night.
APOD: 2014 June 13 - A Strawberry Moon
Explanation:
June's Full Moon (full phase on June 13, 0411 UT) is
traditionally known
as the Strawberry Moon or Rose Moon.
Of course those names might also describe the
appearance of this Full Moon, rising last month
over the small Swedish village of Marieby.
The Moon looks large in the image because the scene was
captured with a long focal length lens from a place
about 8 kilometers from the foreground houses.
But just by eye a Full Moon rising, even on
Friday
the 13th, will appear to loom impossibly large
near the horizon.
That effect has long been recognized as
the
Moon Illusion.
Unlike the magnification provided by a telescope or telephoto lens,
the cause
of the Moon illusion is still poorly understood and
not explained
by atmospheric
optical effects, such as scattering and refraction.
Those effects do produce
the Moon's blushing color and ragged edge also seen
in the photograph.
APOD: 2014 April 18 - Red Moon, Green Beam
Explanation:
This is not a scene
from a sci-fi special effects movie.
The green beam of light and red lunar disk are real enough,
captured in the early morning hours of April 15.
Of course, the reddened lunar disk
is easy to explain as the image was taken during this week's
total lunar eclipse.
Immersed in shadow, the eclipsed Moon
reflects the dimmed reddened light of all the sunsets and sunrises
filtering around the edges of planet Earth,
seen in silhouette
from a lunar perspective.
But the green beam of light really is a laser.
Shot from the 3.5-meter telescope at Apache Point Observatory
in southern New Mexico, the beam's path is revealed as Earth's
atmosphere scatters some of the intense laser light.
The laser's
target is the Apollo 15 retroreflector,
left on the Moon
by the astronauts in 1971.
By determining the
light travel time
delay of the returning laser
pulse, the experimental team from UC San Diego is able to measure
the Earth-Moon distance to millimeter precision and
provide a test of General Relativity, Einstein's theory of
gravity.
Conducting the
lunar
laser ranging experiment during
a total eclipse uses the Earth like a cosmic light switch.
With direct sunlight blocked, the reflector's performance is
improved over performance when illuminated by sunlight during a
normal Full Moon,
an effect known as the real Full Moon Curse.
APOD: 2014 January 21 - Micro Moon over Super Moon
Explanation:
Did you see the big, bright, beautiful Full Moon last Wednesday night?
That was actually a
Micro Moon!
On that night, the smallest Full Moon of 2014 reached its full phase only
a few hours from lunar
apogee,
the time of its the most distant point from Earth in the
Moon's
elliptical orbit.
Of course, last year on the night of June 22,
a Full Super Moon was near perigee, the closest
point
in its orbit.
The relative apparent size of January 15's
Micro Moon is compared to the
June 22 Super Moon in the above
composite image digitally
superimposing
telescopic images from
Perugia, Italy.
The difference
in apparent size represents a difference in distance
of just under 50,000 kilometers between apogee and perigee, given
the Moon's average distance of about 385,000 kilometers.
How long do you have to wait to see another
Full Micro Moon?
Until March 5, 2015, when the lunar full phase will again occur within a few hours of lunar
apogee.
APOD: 2014 January 18 - Apogee's Full Moon
Explanation:
This big, bright, beautiful Full Moon rose over
Lick Observatory Wednesday night.
Traditionally a full moon in January might be called
the Wolf Moon.
But this moon reached its full phase on
January 16, 4:54 UT, within about 2 hours of apogee,
the most distant point in
its
elliptical orbit around planet Earth.
That also makes it the
smallest
full moon of 2014.
Of course the
difference in
apparent size between the largest and
smallest full moons is hard to see, because
the difference in distance between lunar apogee and perigee, or
closest point in the Moon's orbit, is only about 50,000 kilometers,
while the Moon's average distance is around 385,000 kilometers.
Though not by much,
this
apogee's full moon was also the smallest full moon
of the last 1,000 years.
It will keep
that distinction until a slightly smaller full moon occurs
close to apogee in 2154.
APOD: 2014 January 13 - A Trip to the Moon
Explanation:
What would it be like to visit the Moon?
The first major fictional cinematic film exploring this enduring
transcultural fantasy was titled
Le voyage dans la lune (A Trip to the Moon) and made in 1902,
becoming one of the most
popular movies
of the early years of the twentieth century.
The silent film starred the filmmaker
Georges Melies himself and portrayed a
club of astronomers voyaging to the Moon and back.
Pictured above is a frame from the movie that has become an enduring
icon for both film and space.
Alluding to a
bullseye trajectory,
the Man in the Moon
is caricatured as being struck by the
human-built spaceship.
The entire 14-minute film is now
freely
available.
Visiting the Moon remained a
very popular topic even 67 years later in
1969 when humans first made an
actual voyage.
APOD: 2013 September 16 - Rotating Moon from LRO
Explanation:
No one, presently, sees the Moon rotate like this.
That's because the Earth's moon is tidally locked to the Earth, showing us
only one side.
Given modern digital technology, however, combined with many detailed images returned by the
Lunar Reconnaissance Orbiter (LRO), a high resolution virtual
Moon rotation movie has now been composed.
The above time-lapse video
starts with the standard Earth
view of the Moon.
Quickly, though,
Mare Orientale, a large crater with a dark center
that is difficult to see from the Earth, rotates into view just below the equator.
From an entire
lunar month condensed into 24 seconds,
the video clearly shows that the Earth side of the Moon contains an abundance of
dark lunar maria,
while the lunar far side is dominated by bright
lunar highlands.
Two new missions are scheduled to begin exploring the Moon within the year,
the first of which is NASA's
Lunar Atmosphere and Dust Environment Explorer (LADEE).
LADEE, which launched just over a week ago,
is scheduled to begin orbiting the Moon in October
and will explore the thin and unusual
atmosphere of the Moon.
In a few months, the
Chinese
Chang'e 3 is scheduled to launch,
a mission that includes a soft lander that will dispatch a robotic rover.
APOD: 2013 June 28 - A Super Moon's Halo
Explanation:
A Full Perigee Moon
rose as the Sun set last Sunday.
At its closest to Earth it was, by just a bit,
the year's brightest and largest Full Moon
also known as a Super Moon.
Seen from Punta Piedras, Argentina and the mouth of the Rio de La Plata,
near Buenos Aires,
the Super Moon's light created this magnificent
circular lunar
halo.
Still, the size of a lunar halo is determined by the geometry
of six sided water ice crystals in planet Earth's high, thin clouds.
The crystals
deflect the rays
of moonlight more strongly through a minimum angle of 22 degrees.
So this halo has an inner radius of 22 degrees, just like the halos
of the less-than-super moons.
Even more common than a Super Moon, beautiful 22 degree
halos can be spotted at any time of year.
APOD: 2013 June 22 - Perigee's Full Moon
Explanation:
A big, bright, beautiful Full Moon will rise at sunset on Sunday.
Its exact full phase (June 23, 11:32 UT)
will occur shortly before it
reaches perigee,
the closest point to Earth in the Moon's orbit, and make it the
largest Full Moon of 2013.
But
such circumstances are not very rare.
The full lunar phase falls near the Moon's orbit perigee about every
14 lunar
months.
That means the following Full Perigee Moon will be on August 10,
2014, the 14th Full Moon after June 23.
On May 5, 2012, 14 Full Moons ago,
this
inspired telescopic night skyscape captured the Full Perigee Moon
rising over Cape Sounion,
Greece and the ancient
Temple of Poseidon.
APOD: 2013 April 7 - The Moon's Saturn
Explanation:
Just days after sharing the western evening sky
with Venus in 2007, the Moon moved
on to Saturn -
actually passing in
front of the ringed planet Saturn when viewed in skies over
Europe, northern Africa, and western Asia.
Because the Moon and bright planets wander through the sky
near the ecliptic plane, such
occultation events are
not uncommon, but they are
dramatic, especially in
telescopic views.
For example, in this sharp image Saturn is captured
emerging
from behind the Moon, giving the illusion
that it lies just beyond the Moon's bright edge.
Of course, the Moon is a mere 400 thousand kilometers away,
compared to Saturn's distance of 1.4
billion kilometers.
Taken with a digital camera and 20 inch diameter telescope
at the Weikersheim Observatory in southern Germany,
the picture is a single exposure adjusted to reduce the
difference in brightness between Saturn and the
cratered lunar surface.
APOD: 2012 November 29 - Super Moon vs Micro Moon
Explanation:
Did
you see the big, bright, beautiful Full Moon Wednesday night?
That was actually a Micro Moon!
On that night, the smallest Full Moon of 2012 reached its full phase only
about 4 hours before
apogee, the most distant point from Earth in the
Moon's elliptical orbit.
Of course, earlier this year on May 6,
a Full Super Moon was near perigee, the closest
point
in its orbit.
The relative apparent size of November 28's
Micro Moon (right) is compared to the famous
May 6 Super Moon in these two panels,
matching
telescopic images from Bucharest, Romania.
The difference
in apparent size represents a difference in distance
of just under 50,000 kilometers between apogee and perigee, given
the Moon's average distance of about 385,000 kilometers.
How long do you have to wait to see another Full Micro Moon?
Until January 16, 2014, when the lunar full phase will occur within
about 3 hours of apogee.
APOD: 2012 November 6 - Methone: Smooth Egg Moon of Saturn
Explanation:
Why is this moon shaped like a smooth egg?
The robotic Cassini spacecraft completed the first flyby ever of Saturn's small moon
Methone
in May and discovered that the moon has no obvious craters.
Craters, usually caused by impacts, have been seen on every
moon,
asteroid, and comet nucleus
ever imaged in detail -- until now.
Even the Earth and
Titan have
craters.
The smoothness and egg-like shape of the
3-kilometer diameter moon might be caused by
Methone's
surface being able to shift --
something that might occur were the moon coated by a deep
pile of sub-visual
rubble.
If so, the most similar objects in our Solar System would include Saturn's moons
Telesto,
Pandora,
Calypso, as well as asteroid
Itokawa,
all of which show sections that are unusually smooth.
Methone
is not entirely featureless, though, as some surface sections
appear darker than others.
Although flybys of Methone are
difficult, interest in the nature and
history of this unusual moon is sure to continue.
APOD: 2012 November 5 - Saturn's Moon Dione in Slight Color
Explanation:
Why does one half of Dione have more craters than the other?
Start with the fact that
Saturn's moon Dione
has one side that always faces Saturn, and one side that always faces away.
This is similar to
Earth's Moon.
This tidal locking
means that one side of
Dione always leads as the moon progresses in its orbit,
while the other side always trails.
Dione
should therefore have undergone a significant number of impacts on its leading half.
Strangely, the current leading half of
Dione
is less cratered than the trailing half.
A leading explanation is that some crater-forming impacts were so large they spun
Dione,
changing the part that suffered the highest impact rate before the
moon's spin again became locked.
The above detailed image of Dione highlighting the moon's subtle hues
is a meticulously-constructed mosaic --
by an dedicated amateur --
of pictures taken during the April 2010
flyby of Dione by NASA's robotic
Cassini spacecraft.
APOD: 2012 November 3 - Hunter's Moon over the Alps
Explanation:
A Full Moonset
can be a dramatic celestial sight, and Full Moons can
have many names.
Late October's Full Moon,
the second Full Moon after the
northern hemisphere autumnal equinox, has been traditionally called the
Hunter's Moon.
According to lore, the name is a fitting one because this
Full Moon lights the night during a time for hunting
in preparation for the coming winter months.
In this scene,
last week's Hunter's Moon
shines
with a rich yellow light,
setting as dawn comes to the Italian Alps.
Topping out at over 11,000 feet, the snowy peak known as Rochemelon
glows, just catching the first reddened light of the rising Sun.
APOD: 2012 September 1 - On a Blue Moon
Explanation:
Rising at sunset, the gorgeous Full Moon of
August 31 became the second Full Moon in a month.
According to modern reckoning,
that makes it a Blue Moon.
In fact, parts of the Full Moon do look a little blue in
this sharp lunar portrait.
Taken just hours before the exact full phase in
delightfully clear skies over Nottingham, UK, it features
eye-catching bright rays extending from the prominent young
crater Tycho in the Moon's southern hemisphere.
The slightly color enhanced image also brings out
subtle shades of blue, a
real characteristic of
terrain with a high content of titanium oxide and iron.
The blue
lunar terrain on the right includes
the dark flat expanse of the Sea of Tranquility and
the Apollo 11 landing site.
APOD: 2012 May 11 - Sun vs Super Moon
Explanation:
The Super Moon wins, by just a little, when
its apparent size is
compared to the Sun in this ingenious composite picture.
To make it, the Full Moon on May 6 was photographed
with the same camera and telescope used to image the Sun
(with a dense solar filter!) on the following day.
Of course, on May 6 the
Moon was at perigee,
the closest point to Earth in its eliptical orbit,
making it the largest Full Moon of 2012.
Two weeks later, on May 20, the
Moon will be near
apogee, the most distant point in its orbit, so by then it will
be nearly at its smallest apparent size.
It will also be a dark
New Moon on that date.
And for some the New Moon will be surprisingly easy
to compare to the Sun, because on
May 20 the
first solar eclipse of 2012
will be visible from much of Asia, the Pacific, and North America.
Along a path 240 to 300 kilometers wide, the
eclipse will
be annular.
Near apogee the smaller silhouetted Moon will fit just
inside the bright solar disk.
APOD: 2012 May 10 - Green Flash and Super Moon
Explanation:
It was really not
about superheroes as on May 6 the much touted
Super Moon, the largest Full Moon of 2012,
rose over this otherwise peaceful harbor.
And no supervillains
were present either as boats gently
rocked at their moorings near the checkerboard
La Perdrix lighthouse
on the coast of Brittany, France.
But the rise of the Super Moon was preceded by a
Green Flash,
captured in the first frame of this
timelapse video recorded that night.
The cropped image of the frame, a two second long exposure, shows the
strongly colored flash left of the lighted buoy
near picture center.
While the Super Moon was enjoyed
at locations all around the world,
the circumstances that produced the Green Flash were more restrictive.
Green flashes for both
Sun and Moon
are caused by atmospheric
refraction enhanced by long, low, sight lines and strong atmospheric
temperature gradients often
favored by a sea horizon.
APOD: 2012 March 24 - The New Moon in the Old Moon's Arms
Explanation:
Also known as the Moon's ashen glow,
Earthshine is
Earthlight illuminating the Moon's night side.
Taken on
Nowruz,
the March 20 equinox, from Esfahan, Iran, planet Earth,
this telescopic image captures strong Earthshine from
an old Moon.
The darker earthlit disk is in the arms of a bright sunlit crescent.
But the
view
from the Moon would have been enchanting too.
When the Moon appears in Earth's sky as a slender crescent,
a dazzlingly bright, nearly full Earth would be seen
from the lunar surface.
The Earth's brightness due to reflected sunlight
is known to be strongly influenced by cloud cover.
Still, a description of Earthshine, in
terms of sunlight reflected by Earth's oceans in turn illuminating
the Moon's dark surface, was written 500 years ago by
Leonardo
da Vinci.
APOD: 2012 March 20 - Evolution of the Moon
Explanation:
What is the history of the Moon?
The Moon was likely created from
debris expelled when a Mars-sized object violently
impacted the Earth about 4.5 billion years ago.
Just after gravitationally condensing, as
imagined
above, the glowing-hot surface of the Moon cooled and cracked.
Rocks large and small continued to impact the surface, including a particularly large impact that created
Aitken Basin about 4.3 billion years ago.
A Heavy Bombardment period then continued for hundreds of millions of years, creating large basins all over the lunar surface.
Over the next few billion years lava flowed into
Earth-side basins, eventually cooling into the dark maria we see today.
As always, relentless impacts continued, forming the
craters we see today, slowly diminishing over the past billion years.
Today the cooled Moon we know and
love
is as dark as coal and always keeps the same face toward Earth.
Exactly how the
Moon formed initially, and why
lunar maria are only on the Earth side, remain active topics of research.
APOD: 2012 February 11 - A February Moon Halo
Explanation:
Lighting the night last Tuesday, February's
Full Moon is
sometimes called the Snow Moon.
But the Moon
was not quite full in this mosaicked skyscape
recorded on February 2 south of Budapest, Hungary,
and there was no snow either.
Still, thin clouds of ice crystals hung in the cold,
wintry sky creating this gorgeous lunar halo.
Refraction of moonlight by the six-sided
crystals produce the
slightly colored halo with its characteristic radius of
22 degrees.
Just below the Moon is bright star Aldebaran.
Also well within
the halo at the right is the Pleiades star cluster.
At the lower left, near the halo's edge lie the
stars of Orion
with bright Capella, alpha star of the
constellation Auriga,
just beyond the halo near the top of the frame.
APOD: 2012 January 20 - The Wolf's Moon
Explanation:
A Full Moon rising
can be a dramatic celestial
sight, and
Full Moons can have many names.
Captured on January 8 from Östersund, Sweden, this
evocative
moonrise portrait might make you feel the cold
of winter in the north.
If you can also imagine wolves howling in the distance then
you probably understand why Native Americans
would have called it the Wolf Moon, their
traditional name for
the first Full Moon in January.
The photographer reports that no wolves were heard
though, as he watched this beautiful Full Moon rise in
fading light over the eastern horizon,
echoing
the yellow color of the
setting Sun.
Of course, due this year on February 7, the next Full Moon will be
the Snow Moon.
APOD: 2012 January 2 - Spot the Moon
Explanation:
Where's the full Moon?
Somewhere in this image, the Earth's Moon is hiding.
The entire Moon is visible, in its completely full phase, in plain sight.
Even the photographer's keen eye couldn't find it even though he knew exactly where to look -- only the
long exposure of his camera picked it up -- barely.
Although by now you might be congratulating yourself on finding it, why was it so difficult to see?
For one reason, this photograph was taken during the
total lunar eclipse last month, when the Earth's shadow made the Moon much dimmer than a normal full Moon.
For another, the image, taken in
Colorado,
USA,
was captured just 12 minutes before sunrise.
With the Moon on the exact opposite side of the sky from the Sun, this meant that the Sun was just below the horizon, but still
slightly illuminating
the sky.
Last, as the
Moon was only about two degrees above the horizon, the
large volume of air between the camera and the horizon scattered a lot of light away from the
background Moon.
Twelve minutes after this image was acquired the Sun peeked over the horizon and the Moon set.
APOD: 2011 November 27 - Shuttle Plume Shadow Points to the Moon
Explanation:
Why would the shadow of a
space shuttle
launch plume point toward the Moon?
In early 2001 during a launch of
Atlantis,
the Sun,
Earth,
Moon,
and rocket were all properly aligned for
this
photogenic coincidence.
First, for the
space shuttle's plume to cast a long shadow,
the time of day must be either near
sunrise or
sunset.
Only then will the
shadow
be its longest and extend all the way to the
horizon.
Finally, during a
Full Moon, the
Sun and
Moon are on
opposite sides of the sky.
Just after
sunset, for example, the Sun is slightly below the
horizon, and,
in the other direction, the Moon is slightly above the horizon.
Therefore, as
Atlantis blasted off, just after
sunset,
its shadow projected away from the Sun
toward the opposite horizon, where the
Full Moon just happened to be.
APOD: 2011 March 20 - Parthenon Moon
Explanation:
Did you see the Full Moon last night?
Near the horizon,
the lunar orb may have seemed to loom large,
swollen in appearance by the famous
Moon illusion.
But the Full Moon really was a large Full Moon last night,
reaching its exact full phase within an hour of
lunar perigee, the
point in the Moon's elliptical orbit closest to planet Earth.
A similar near perigee Full Moon last occurred on
December 12, 2008.
The difference in the Moon's apparent size as it moves from perigee
to apogee, its farthest point from Earth, is about 14 percent.
Of course, a nearly Full Moon will rise again tonight, lighting
the skies on the date of the Equinox
or equal night.
The Full Moon also looms large in this
well-planned,
telescopic lunar portrait.
Captured earlier this year, the rising lunar orb is dramatically
matched to the 2,500 year old
Parthenon in Athens, Greece.
APOD: 2011 February 28 - Red Snow Moon over Edmonton
Explanation:
What's hovering between those buildings?
The Moon.
The above image was taken two weeks ago as the
full Snow Moon started to rise above
Edmonton,
Alberta,
Canada.
The odd coincidence between the
angular size of the
far distant Moon
and the angular width of nearby buildings created a striking juxtaposition.
Backing away from the buildings so to reduce their angular size was a key to planning the image.
The temperature was so low, -25
C,
that plumes of steam rose from neighboring oil refineries.
The above image was taken during a momentary break in the plumes.
The rising Moon appears red here for the same reason that a setting
Sun appears red -- because blue light is preferentially
scattered away by intervening air.
In this case, the
shimmering steam plumes
likely also caused the Moon to appear
slightly compressed.
The next full moon, the
full Worm Moon, will occur in mid-March.
APOD: 2010 September 24 - Equinox and the Harvest Moon
Explanation:
Did you enjoy the moonlight last night?
The Full Moon closest to autumnal equinox and the beginning
of Fall is traditionally
known as the Harvest Moon,
rising opposite the Sun and illuminating
fields at harvest time after sunset.
This year's northern hemisphere autumnal equinox occurred yesterday,
September 23rd, at 03:09 Universal Time.
The Moon was at its
full phase
a mere 6 hours later --
exceptionally close for a Harvest Moon!
Of course, the Moon still shines brightly through the night in
surrounding days.
In this picture from September 22nd, the
lunar orb dominates
the sky above a ruined church in Zsámbék, Hungary.
Shining nearby, the brightest star is actually Jupiter, also
opposite the Sun,
seen here through thin clouds just left of the church wall.
APOD: 2010 June 6 - Lunokhod: Reflections on a Moon Robot
Explanation:
It may look like some sort of cute alien robot, but it was created here on Earth, launched to the Moon in 1970, and now reflects laser light in a scientifically useful way.
On November 17, 1970 the Soviet
Luna 17 spacecraft landed the first roving remote-controlled robot
on the Moon.
Known as
Lunokhod 1,
it weighed just under 2,000 pounds and was
designed to operate for 90 days while
guided in real-time by a five person team near Moscow, USSR.
Lunokhod 1 toured
the lunar Sea of Rains (Mare Imbrium) for 11 months in one of the
greatest successes of the
Soviet lunar exploration program.
This Lunokhod's operations officially ceased in 1971.
Earlier this year, however, the position of the rover was recovered by NASA's moon-orbiting
Lunar Reconnaissance Orbiter.
Given that position, laser pulses from Earth were successfully bounced off the old robot's reflector.
Bouncing laser pulses off of this and other lunar reflectors could yield range data to the moon accurate enough to track millimeter-sized
deviations in the Moon's orbit, effectively probing lunar composition and testing gravitational theories.
APOD: 2010 May 16 - Crescent Venus and Moon
Explanation:
There's something behind these clouds.
Those faint graceful arcs, upon inspection, are actually far, far in the distance.
They are the
Earth's Moon and the
planet Venus.
Both the Moon and Venus
are bright enough to be seen during the day, and both are quite capable of showing a
crescent phase.
To see Venus, which appears quite small, in a
crescent phase requires
binoculars or a telescope.
In the
above dramatic daytime image taken from
Budapest,
Hungary in 2004, the
Moon and Venus shared a similar crescent
phase a few minutes before the
Moon eclipsed the larger but more distant world.
Similarly, visible today in parts of Africa and Asia, a crescent Moon will again
eclipse Venus during the day.
About an hour after the above image was taken, Venus reappeared.
APOD: 2010 January 2 - Blue Moon Eclipse
Explanation:
The International Year
of Astronomy 2009 ended with
a Blue Moon and a
partial lunar eclipse,
as the second Full Moon of December
grazed the Earth's
shadow on December 31st.
The New Year's Eve Blue Moon eclipse was
visible throughout Europe, Asia, Africa and parts of Alaska,
captured in this two exposure composite in
cloudy skies over Saint Bonnet de Mure, France.
Playing
across the Moon's southern reaches, the
edge
of Earth's umbra, or
dark central shadow, appears on the right side along
with the prominent ray crater Tycho.
At maximum eclipse, the umbra covered only
about 8 percent of the diameter of the lunar disk.
APOD: 2010 January 1 - Not a Blue Moon
Explanation:
This bright Full Moon was captured on December 2nd,
shining above a church overlooking the River Po, in Turin, Italy.
It was the first
Full Moon
in December.
Shining on celebrations of New Year's Eve,
last night's Full Moon was the second Full Moon of December and
so fits the modern definition
of a Blue Moon -
the second Full Moon in a month.
Because the lunar cycle,
Full Moon to Full Moon, spans 29.5 days,
Blue Moons tend to occur in some month about every 2.5 years.
Shining in the glare just above and right of December's first
Full Moon is the Pleiades star cluster.
APOD: 2009 November 18 - Water Discovered in Moon Shadow
Explanation:
Why is there water on the Moon?
Last month, the
LCROSS mission crashed a large
impactor into a
permanently shadowed crater near the
Moon's South Pole.
A plume of dust rose that was visible to
the satellite,
although hard to discern from Earth.
The plume is shown above in visible light.
Last week, the results of a preliminary chemical analysis gave a clear indication that the
dust plume contained water.
Such water is of importance not only for understanding the
history of the Moon,
but as a possible reservoir for future astronauts trying to
live on the Moon for long periods.
The source of the
lunar water
is now a topic of debate.
Possible origins include many small meteorites,
a comet, or primordial
moon soil.
APOD: 2009 October 3 - Old Faithful Moon
Explanation:
Scheduled to illuminate the landscape
throughout the night tomorrow, October's
bright Full Moon will also be
called the Harvest Moon.
Traditionally, the Harvest Moon is the Full Moon closest to the
autumnal equinox.
But in this vacation snapshot, the Full Moon could be called
the "Old Faith-Full Moon".
Taken on September 4, the picture combines
the regularly occurring lunar phase with
Old Faithful Geyser in
Yellowstone National Park,
named for its dependable erruptions.
Shining on the well-known geyser's
towering pillar from behind,
the moonlight creates an eerie halo surrounding convoluted shapes.
Faithfully, the Full Moon itself is bright enough to be seen
through the dense swirling steam near the top.
APOD: 2009 September 28 - Water Discovered on the Moon
Explanation:
Water has been discovered on the surface of the Moon.
No lakes have been found, but rather NASA's
Moon Mineralogy Mapper aboard India's new
Chandrayaan-1
lunar orbiter radios back that parts of the Moon's surface absorb a very specific color of light identified previously only with water.
Currently, scientists are trying to fit this with other facts about the
Moon to figure out how much water is there, and even what form this water takes.
Unfortunately, even the
dampest scenarios leave our moon dryer than the
driest of Earth's deserts.
A fascinating clue being debated is whether the
water signal rises and falls during a single lunar day.
If true, the signal might be explainable by hydrogen flowing
out from the Sun and interacting with
oxygen in the lunar soil.
This could leave an extremely thin
monolayer
of water, perhaps only a few molecules thick.
Some of the resulting water might subsequently evaporate away in bright sunlight.
Pictured above, the area near a crater on the
far side of the Moon shows a
relatively high abundance of water-carrying minerals in false-color blue.
Next week, the new LCROSS satellite will release an
impactor that will strike a
permanently shadowed crater
near the lunar south pole to see if any hidden water or ice sprays free there.
APOD: 2009 June 20 - Seaside Moon Mirage
Explanation:
This surprising view of the Full Moon
rising on
June 7 was captured
with a telephoto lens from a seaside balcony near Nice, France.
The orange Moon's
dark markings and odd shape put the photographer
in mind of an alien creature's face staring down at the passing ship.
Of course, the Moon's distorted appearance is due to the unusual bending
(refraction) of light rays
creating multiple images or
mirages, similar to
sunset and
sunrise mirages.
The effects are most pronounced when
temperature
layers in the atmosphere produce sharp changes in air density and
refractive index.
Acting over long sight-lines to the rising and setting Sun or Moon,
the refraction significantly alters the
path of
light rays creating merged, distorted images.
Such mirages are also associated with the
Green Flash.
APOD: 2009 April 16 - Castle and Full Moon
Explanation:
Clouds couldn't hide this bright Full Moon
as it rose last week over the
medieval castle of Tourrette-Levens near Nice,
France.
Exactly full on April 9 at 1456 UT, it followed
the March equinox, making it the first
Full Moon of spring
in the north and autumn in the southern hemisphere.
Known as the Easter Moon, it fixes the date for the
celebration
of Easter
on the first Sunday after the first Full Moon of northern
spring.
Also called
the Grass Moon or Egg Moon in the north,
in the southern hemisphere, following the autumnal equinox,
this Full Moon shines
throughout the night as a Hunter's Moon.
APOD: 2009 February 23 - An Etruscan Vase Moon Rising
Explanation:
What's happened to the Moon?
Nothing, although from some locations, February's full moon,
which occurred about two weeks ago, appeared
strangely distorted as it rose.
Visible in particular was a
curiously
inverted image section pinched off
near the horizon,
an effect dubbed the Etruscan vase by the pioneering science fiction writer
Jules Verne for its familiar shape.
This odd moon image piece was created by moonlight
refracting through an
atmospheric inversion layer on
Earth where cold air was
trapped near the surface.
The photographer also reported that, as the moon rose, a
red rim was faintly
visible on the lower part of the moon, while a
green rim appeared on the top.
Similar to the Sun's famous
green flash, these
effects arise
when the Earth's atmosphere acts like a
prism, sending different colors of light on slightly
different paths.
The above image mosaic has been
horizontally compressed by computer
to fit a standard screen.
APOD: 2009 January 13 - Largest Full Moon of 2009
Explanation:
A larger moon will not be seen this year.
This past weekend, the
largest full Moon of 2009
could be seen from almost any clear location on planet
Earth at night.
The large
angular extent
of the full Moon was caused by the Moon
being unusually close to Earth during its
full phase.
Because the Moon circles the Earth in an elliptical orbit,
its angular size depends on how close the Moon
is to closest approach (perigee) or farthest distance
(apogee).
Even so, the Moon's was only about 15 percent larger in area and brightness than a more typical full Moon.
In
this image,
a dramatically positioned Moon is seen
rising above the
Alps from
Breil-sur-Roya
in the southeast of France.
Taken with an ordinary digital camera but extraordinary timing,
the image also captured a
crossing jet plane.
The last full Moon, in 2008 December, was the
largest full moon of 2008.
APOD: 2008 August 1 - Moon Games
Explanation:
The Moon's measured
diameter is around 3,476 kilometers (2,160 miles).
But apparent
angular size,
or the angle covered by an object, can also
be important to
Moon enthusiasts.
Angular size depends on distance, the farther away an object is, the
smaller an angle it covers.
Since the Moon is 400,000 kilometers away, its angular size
is only about 1/2 degree,
a span easily covered by the tip of your finger held
at arms length, or a measuring tape held in the distance by a friend.
Of course the
Sun is much larger than the Moon, 400 times larger
in fact, but today the New Moon will just cover the Sun.
The total solar eclipse can be seen along a track
across northern Canada, the Arctic, Siberia, and northern China.
(A partial eclipse is visible from a broader region).
Solar eclipses
illustrate the happy coincidence that while the
Sun is 400 times the diameter of the Moon, it is also 400 times
farther away giving the Sun and Moon exactly
the same angular size.
APOD: 2008 June 7 - June's Young Crescent Moon
Explanation:
Serene skyviews were enjoyed across planet Earth
earlier this week with a young
crescent Moon
low in the western sky just after sunset.
Recorded on June 4,
this
colorful example
includes a quiet beach
in the foreground with the city lights of Lisbon, Portugal,
and the Sintra Mountains along the horizon.
Posing between cloud banks, the Moon's slender, sunlit arc
represents only about 1 percent of the full lunar disc.
The rest of the Moon's nearside is faintly visible though,
illuminated
by Earthshine.
A waxing crescent Moon should
also create some lovely western skies at dusk
this
weekend.
The bright star in the sky near tonight's (Saturday's) Moon will
actually be the planet Mars.
On Sunday the Moon will move closer to a pair of celestial
beacons, bright star Regulus
and Saturn.
APOD: 2008 April 11 - At first he couldn't see the Moon
Explanation:
At first, he couldn't see it, but searching with binoculars
along a cloudy western horizon near sunset,
photographer
Laurent Laveder finally spotted a delicate lunar crescent.
Captured in this
dramatic picture
on April 6th from Bretagne, France,
the Moon was only 15 hours and 38 minutes old.
Its slight, irregular, sunlit arc opens upward
just above the dark cloud bank near picture center.
Of course, a
crescent Moon in the
early evening sky is a
lovely sight often
enjoyed by many.
But finding the Moon when its slim crescent is still
less than about 24 hours past the New Moon phase requires
careful timing and planning,
a challenging project even for experienced
observers.
In this sighting, only about 0.8 percent of the Moon's
disk appears illuminated.
Laveder notes that this is the
youngest Moon he has spotted in
twenty years of skygazing and also offers this animation
(Flash
or gif)
based on his images of the tantalizing celestial
scene.
APOD: 2008 March 15 - Moon over Byzantium
Explanation:
Hiding near the Sun, a slender
crescent
Moon is a difficult but
rewarding sight.
Look to the right (scroll right) and you can
spot one
in this twilight panorama
across
the Bosporus Strait and along the
skyline of the historic city of
Istanbul.
Recorded on March 8, the Moon is a mere 22
hours young.
A thin, curved edge of the Moon's illuminated surface is just visible
poised in the
western sky
at sunset above the walls of
Topkapi
Palace.
The palace was built in the reign of Ottoman Sultan Mehmed II,
the 15th century conquerer of the city that was then
Constantinople, capital of the Byzantine Empire.
The well-lit domed building immediately to the left of the
palace is Ayasofya
(Hagia Sophia),
a famous example of Byzantine architecture, now a museum.
Still farther to the left is the
Sultan Ahmed Mosque
APOD: 2007 December 23 - Moon and Mars Tonight
Explanation:
The Full Moon and a brilliant, ruddy Mars
will share
the sky tonight.
Skygazers can easily
enjoy the celestial pairing
as the two are
separated by
a degree or even less.
In fact, seen from parts of northern North America and
Europe, the Moon will actually
occult (pass in front of) the Red Planet.
Mars is so bright because it is
near opposition, opposite the Sun in Earth's sky and
near its closest approach to planet Earth.
But Mars is not nearly as bright as the
Moon, also opposite the Sun tonight.
In this striking preview of tonight's sky show, backyard
astronomer John Harms was able to photograph an almost Full Moon
near Mars last month.
His simple, single exposure relied on clouds
to block some of the overwhelming
moonlight.
APOD: 2007 October 25 - Apogee Moon, Perigee Moon
Explanation:
Tonight, those blessed with clear skies can enjoy
a glorious Full Moon,
(exact full phase at 0452 UT, October 26).
In fact, the Moon will
reach its full phase within a few hours of
perigee,
the closest point in its
elliptical orbit,
making it the largest Full Moon of 2007.
On April 3, the Full Moon was within hours of apogee,
the farthest point in the lunar orbit,
corresponding to the smallest Full Moon of 2007.
The difference in apparent size between the largest and smallest Full
Moon is quite dramatic and similar to
this
side by side comparison of the lunar
apogee/perigee
apparitions from 2006.
But seen in the sky many months apart, the change is difficult to notice.
Skygazers should
also enjoy the Moon on Saturday, October 27, as
it encounters the lovely
Pleiades star cluster.
Because the Moon will be so bright, it will be easiest to spot the
Pleiades stars near the Moon with binoculars or a small telescope.
APOD: 2007 September 26 - Saguaro Moon
Explanation:
A Full Moon rising
can be a dramatic celestial
sight, and
Full Moons can have many names.
For example, tonight's Full Moon, the one nearest the
autumnal equinox
in the northern hemisphere, is popularly
called the Harvest Moon.
According
to lore the name is a fitting one because farmers
could work late into the night at the end of the growing season
harvesting crops by moonlight.
In the same traditions, the Full Moon following the
Harvest Moon is
the Hunter's Moon.
But, recorded on a trip to the American southwest, this
contribution to compelling images of
moonrise is appropriately titled
Saguaro Moon.
APOD: 2007 June 3 - Shuttle Plume Shadow Points to Moon
Explanation:
Why would the shadow of a
space shuttle
launch plume point toward the Moon?
In early 2001 during a launch of
Atlantis,
the Sun,
Earth,
Moon,
and rocket were all properly aligned for
this
photogenic coincidence.
First, for the
space shuttle's plume to cast a long shadow,
the time of day must be either near
sunrise or
sunset.
Next, just at sunset, the
shadow
is the longest and extends all the way to the
horizon.
Finally, during a
Full Moon, the
Sun and
Moon are on
opposite sides of the sky.
Just after
sunset, for example, the Sun is slightly below the
horizon, and,
in the other direction, the Moon is slightly above the horizon.
Therefore, as
Atlantis blasted off, just after
sunset,
its shadow projected away from the Sun
toward the opposite horizon, where the
Full Moon just happened to be.
APOD: 2007 June 2 - 3D Full Moon
Explanation:
Get out your
red/blue glasses and check
out this satisfying
stereo anaglyph
of the Full Moon.
A corresponding stereo image pair, intended for
cross-eyed viewing,
is also available through this link.
Regardless of your preferred technique
for stereo
viewing, the 3D effect comes from combining pictures of the same scene
taken at different angles -- mimicking the slightly different
perspective of each eye.
Perhaps surprisingly for
Earthdwellers, getting two pictures of the
Full Moon from different angles only requires a little patience.
In this case, photographer Laurent Laveder used pictures taken
months apart, one in November 2006 and one in January 2007.
He relied on the Moon's continuous
libration
or wobble as it orbits to produce two shifted images of
a Full Moon.
APOD: 2007 May 26 - The Moon's Saturn
Explanation:
On May 22nd, just days after sharing the western evening sky
with Venus, the Moon moved
on to Saturn -
actually passing in
front of the ringed planet when viewed in skies over
Europe, northern Africa, and western Asia.
Because the Moon and bright planets wander through the sky
near the ecliptic plane, such
occultation events are
not uncommon, but they are
dramatic, especially in
telescopic views.
For example, in this sharp image Saturn is captured
emerging
from behind the Moon, giving the illusion
that it lies just beyond the Moon's bright edge.
Of course, the Moon is a mere 400 thousand kilometers away,
compared to Saturn's distance of 1.4
billion kilometers.
Taken with
a digital camera and 20 inch diameter telescope
at the Weikersheim Observatory in southern Germany,
the picture is a single exposure adjusted to reduce the
difference in brightness between Saturn and the
cratered lunar surface.
APOD: 2007 March 20 - A Blue Crescent Moon from Space
Explanation:
What's happening to the Moon?
Drifting around the Earth in 2006 July, astronauts from the
International Space Station (ISS) captured a
crescent Moon floating far beyond the horizon.
The captured above image is interesting because part of the
Moon appears blue,
and because part of the moon appears missing.
Both effects are created by the
Earth's atmosphere.
Air molecules
more efficiently scatter increasingly blue light, making the clear
day sky blue for ground observers, and the horizon blue for astronauts.
Besides reflecting sunlight, these
atmospheric molecules
also deflect moonlight, making the lower part of the moon appear to fade away.
As one looks higher in the
photograph, the increasingly thin atmosphere appears to
fade to black.
APOD: 2007 March 2 - Solar Eclipse from the Moon
Explanation:
Parts of Saturday's (March 3)
lunar
eclipse will be
widely visible.
For example, skywatchers
in Europe, Africa, and western
Asia will be able to see the entire spectacle of the
Moon gliding through Earth's shadow,
but in eastern North America the Moon will rise
already in its total
eclipse phase.
Of course if you traveled
to the Moon's near side,
you could see the same event as a solar eclipse, with
the disk of
our
fair planet Earth completely
blocking out the Sun.
For a moon-based observer's view,
graphic artist Hana Gartstein
(Haifa, Israel)
offers this composite illustration.
In the cropped version of her picture, an
Apollo 17 image of
Earth is surrounded with a red-tinted haze as
sunlight streams
through the planet's dusty atmosphere.
Earth's night
side remains faintly visible, still
illuminated by the dark, reddened Moon, but
the disk of the Earth would appear almost four times
the size of the Sun's disk, so the faint corona surrounding
the Sun would be largely obscured.
At the upper left,
the Sun itself is just
disappearing
behind the Earth's limb.
APOD: 2007 February 25 - The Far Side of the Moon
Explanation:
Does this moon look familiar? Possibly not, even though it is Earth's Moon.
Locked in synchronous rotation, the
Moon
always presents its well-known near side to Earth.
But from lunar orbit,
Apollo astronauts
also grew to know the Moon's far side.
This
sharp picture from
Apollo 16's
mapping camera shows the eastern edge of the
familiar near side (top)
and the strange and heavily cratered
far side of the Moon.
Surprisingly, the rough and
battered surface of the far side
looks very different
from the near side which is covered with
smooth dark lunar maria.
The likely explanation is that the
far side crust is thicker,
making it harder for molten material from the interior to flow to the surface and form the
smooth maria.
APOD: 2006 September 11 - Eclipsed Moon Rising Over England
Explanation:
Last Thursday, part of our Moon turned dark.
The cause, this time, was not a partial
lunar phase -- the Moon was full --
but rather that part of the Moon went into Earth's shadow.
The resulting partial
lunar eclipse was visible from the eastern
Atlantic Ocean
through
Europe,
Africa, and
Asia and into the western
Pacific Ocean.
The darkest part of the
lunar eclipse, when part of the Moon was completely
shielded from sunlight,
lasted about 90 minutes.
Pictured above, a partially eclipsed Moon is seen rising over an estate in
Huddersfield,
England.
The above image was taken far away from the house in the foreground,
as only this would allow it to appear as angularly small as the
half-degree Moon far in the background.
A setting twilight Sun lit the foreground.
The next eclipse
of the Moon will occur in March 2007.
APOD: 2005 December 15 - Autumn Moon Encore
Explanation:
Near its northernmost declination,
tonight's Full Moon will
be a special one,
arcing high in northern hemisphere skies.
But a Full Moon won't occur on this
calendar date for another 19 years, a period known as the
lunar Metonic cycle.
September 15th's lunar phase and date were notable too,
marking the return of a gibbous Moon rising over
the High Sierra mountains.
That scene was captured in
Ansel
Adams' famous
photograph Autumn Moon from Glacier Point,
Yosemite National Park.
Earlier this year,
Texas State University physicists Donald Olson,
Russell Doescher and students were able to pinpoint the location
and (formerly uncertain) date the original
Ansel Adams photo was
taken - September 15, 1948.
Accordingly, their astronomical detective work predicted that
the lunar alignment and waxing gibbous phase would be repeated on
Thursday, September 15, 2005, exactly three 19-year Metonic
cycles later.
On that day, about 300 photographers gathered at Glacier Point to record
Ansel
Adams' Autumn Moon encore.
APOD: 2005 November 23 - Pandora: A Shepherd Moon of Saturn
Explanation:
What does Saturn's small moon Pandora look like?
To help find out, the
robot Cassini spacecraft
now orbiting Saturn passed about 50,000 kilometers from the unusual moon in
early September.
The highest resolution image of Pandora ever taken was then captured and is
shown above in representative colors.
Features as small as 300 meters can be discerned on 80-kilometer wide
Pandora.
Craters on Pandora appear to be covered over by some sort of material,
providing a more smooth appearance than sponge-like
Hyperion, another small moon of
Saturn.
Curious grooves and
ridges
also appear to cross the surface of the small moon.
Pandora
is partly interesting because, along with its companion moon
Prometheus,
it helps shepherd the particles of
Saturn's F ring
into a distinct ring.
APOD: 2005 August 26 - Full Moon, Green Rim
Explanation:
July's Full Moon
looks strangely darkened and distorted in
this remarkable
telescopic view.
The image is one of
a
series recorded when the Moon was very near
the horizon.
The long sight-line through a turbulent atmosphere
gives rise to the tantalizing optical effects,
including the thin "mirage" shape that seems to
float just above the Moon's upper edge.
Also seen (more easily in the inset),
along the Moon's upper edge is a noticeable
green rim.
Substantial atmospheric refraction produces this
prism-like effect -- related to the
more commonly witnessed
green flash of the setting Sun.
Careful inspection of the full image reveals a corresponding red
rim along the lower edge, another intriguing signature of
atmospheric
refraction.
APOD: 2005 July 13 - Analemma of the Moon
Explanation:
An analemma
is that figure-8 curve you get when you mark
the position of the Sun at the same
time each day for one year.
But the trick to imaging
an analemma of the Moon is to understand
that on average the
Moon
returns to the same position in the sky
about 51 minutes later each day.
So, if you
photograph
the Moon 51 minutes later on successive days, over
one lunation or
lunar month it will trace out an
analemma-like curve as the actual position of the Moon
wanders compared to the average --
due to the Moon's tilted and elliptical orbit.
For this excellent demonstration of the lunar analemma, astronomer
Rich Richins chose the lunar month containing this year's
northern hemisphere
summer
solstice.
The southernmost
Full Moon rises at the lower right
above the Organ Mountains in southern New Mexico, USA,
with the New Moon phase at the upper left.
The multiple exposure image required some digital
manipulation, particularly to include thin crescent phases in
daytime
skies.
APOD: 2005 May 23 - A Wavemaker Moon in Saturn's Rings
Explanation:
What causes small waves in Saturn's rings?
Observations of rings bordering the
Keeler gap in
Saturn's rings showed unusual waves.
Such waves were first noticed last July and are
shown above in clear detail.
The picture is a digitally foreshortened
image mosaic taken earlier this month by the
robot Cassini spacecraft now orbiting
Saturn.
The rings, made of many
small particles, were somehow not orbiting Saturn in their usual manner.
Close inspection of the
image shows the reason - a small moon is orbiting in the Keeler gap.
The previously unknown moon is estimated
to span about seven kilometers and appears to have the same
brightness as nearby ring particles.
The gravity of the small moon likely perturbs the orbits of
ring particles that come near it,
causing them to shimmy back and forth after the moon passes.
Since inner particles orbit more quickly than outer particles,
only the leading particles of the inner rings and the
trailing particles of the outer rings show the wave effect.
APOD: 2005 May 13 - When the Moon Was Young
Explanation:
Remember when the Moon was young?
It was just last Monday.
On May 9th, this slender crescent Moon
was recorded at
a tender age of 34 hours and 18 minutes.
Well, OK ... when calculating the
lunar age during a
lunation or complete
cycle
of phases - from New Moon to Full Moon and
back to New Moon again - the Moon never
gets more than
around
29.5 days old.
Still, a young Moon can be a
rewarding sight, even for
casual skygazers, though the slim crescent is relatively
faint and only easy to see
low in
the west as the sky
grows dark after sunset.
Sighting this young Moon last
Monday, lucky astronomer Stefan Seip was also treated to a very
dramatic telescopic view of an airliner flying
in front of the distant sunlit crescent.
At a high altitude, the jet's stunning contrails reflect
the strongly reddened light of the Sun setting below the
western horizon.
APOD: 2005 March 18 - Moon, Mercury, Monaco
Explanation:
Low on the western horizon after sunset, a
slender crescent Moon and
wandering planet Mercury join
the lights of Menton and Monaco
along the French Riviera.
Astronomer
Vincent Jacques took advantage of this
gorgeous photo opportunity
a week ago on March 11, when the Moon and Mercury
were separated in the sky by just three degrees.
Of course, the Moon in a slender crescent
phase
is always
seen near the horizon, as is Mercury - a bright planet which
can be otherwise difficult to glimpse as it never strays far
from the Sun in Earth's sky.
In the coming days
good views of Mercury will indeed be
fleeting as the solar system's
innermost
planet is rapidly
dropping closer to the glare of the setting Sun.
But tonight a waxing Moon will join another bright planet
wandering overhead
through the evening sky,
Saturn.
APOD: 2004 November 13 - Moon Over Shiraz
Explanation:
Early morning risers
around the world have enjoyed the
sight of bright planets
in this week's predawn skies -
further enhanced by the celestial spectacle of the waning
crescent Moon.
From some locations the Moon was seen to pass in front
of
Jupiter or Venus, a lunar occultation.
Recorded near sunrise on November 10th from
Shiraz, Iran, this
eastern horizon view finds Jupiter (top) and a brilliant Venus
in line with
the Moon, a lovely conjunction of the three brightest
objects in the night sky.
Although the Moon has
now
fallen out of the early morning
scene,
Venus and Jupiter (along with a much fainter Mars) still precede
the rising Sun above the eastern horizon.
APOD: 2004 October 21 - Apogee Moon, Perigee Moon
Explanation:
Why don't these pieces fit?
This third quarter Moon (left) and first quarter Moon were
both photographed during the last lunar cycle or
lunation with the
same telescope and camera.
But, simply combining the pictures into one sharp, full
surface view
would clearly be a problem.
In fact, on October 6th the Moon's third quarter phase
happened to occur near
lunar
apogee, the farthest point in the Moon's
orbit.
On September 21st, the first quarter phase fell close to
lunar
perigee, the Moon's closest approach to planet Earth.
Viewed two weeks apart,
the resulting difference in apparent sizes would not be
noticed by casual skygazers, but the
simultaneous side by side comparison makes it hard to ignore.
Skygazers will likely
notice the Moon
next week though,
as it slides through Earth's shadow during October 27th's
total lunar eclipse.
APOD: 2004 July 31 - Tonight: A Blue Moon
Explanation:
How often does a full moon occur twice in a single month?
Exactly once in a
Blue Moon.
In fact, the modern usage of the term "Blue Moon" refers to the
second Full Moon in a single month.
Tonight's Blue Moon will be the first since November 2001.
A Blue Moon typically occurs every few years.
The reason for the rarity of the
Blue Moon is that the 29.53 days between full moons is
just slightly shorter than the number of days in the average month.
Don't, however, expect the moon to look blue tonight!
The term "Blue Moon" has recently been traced to an error in a
magazine article in 1946.
It is possible for the
Moon to appear tinged by a blue hue, sometimes caused by fine dirt circulating in the
Earth's atmosphere, possibly from a volcanic explosion.
The above picture was taken not during a full moon but through a morning sky that appeared dark blue.
The bright crescent is the only part directly exposed to sunlight - the rest of the Moon glows from sunlight reflected from the Earth.
In this dramatic photo, however, the planet
Jupiter
is also visible along with its
four largest moons.
APOD: 2003 December 25 - Venus and the 37 Hour Moon
Explanation:
At Table
Mountain Observatory, near Wrightwood California, USA
on October 26, wild fires were approaching
from the east.
But looking toward the west just
after sunset,
astronomer James Young could still enjoy this comforting
view of a
young
crescent Moon and brilliant
Venus through the the fading twilight.
Setting over the horizon of Mt. Baden-Powell, the thin crescent
was only about 37 hours "old", or 37 hours after its exact New
Moon phase.
After disappearing from morning
twilight in August,
Venus was
becoming prominent in its role
in western skies as the
evening star.
A similar lovely pairing of thin crescent Moon and stunning
evening star can be seen toward the west in
today's evening twilight.
Happy Holidays and Best Wishes from
APOD!
APOD: 2003 November 22 - Moon AND Sun
Explanation:
This composite image was made from 22 separate pictures
of the Moon and Sun all taken from
Chisamba, Zambia during the
total phase of the 2001 June 21 solar eclipse.
The multiple exposures
were digitally processed and combined to
simultaneously show a wealth of detail which no single camera
exposure or naked-eye observation could easily reveal.
Most striking are the incredible flowing streamers
of the Sun's outer atmosphere or
solar corona, notoriously difficult to see except when
the
new Moon blocks the bright solar disk.
Features on the darkened near side
of the Moon can
also be made out,
illuminated
by sunlight reflected from
a
full Earth.
A giant solar prominence seems to hang
just beyond the Moon's eastern (left) edge while about one
diameter farther east of the eclipsed Sun is the
relatively faint (4th magnitude)
star 1 Geminorum.
The still active
Sun
will be totally eclipsed by the Moon tomorrow,
but the path of the total eclipse will mostly cross the relatively
inaccessible continent
of Antarctica.
APOD: 2003 June 19 - The Moon Maiden
Explanation:
Along the northwestern reaches of the
lunar
near side, the
Sinus Iridum
or Bay of Rainbows appropriately
lies at the edge of the Moon's smooth, dark Sea of Rains (Mare Imbrium).
In this sketch of
the lunar surface around the
Bay of Rainbows,
the sun shines from the left, illuminating the
arcing wall of the lava-floored bay.
The bay's Cape Heraclides, seen here at the top of the sunlit arc,
has been historically depicted as a moon maiden whose
hair streams behind her as she gazes sunward across the bay.
In the original Moon race - the race
to map
the Moon - this moon
maiden first appeared in
telescope-based
drawings of the lunar
surface by astronomer
Giovanni
Cassini in 1679.
Still gazing across the lunar bay, the moon maiden inspired
this drawing
by modern day astronomer, Lucy Whitehouse.
Done when she was 14, her sketch of the intriguing feature was made
from the countryside in northern England,
aided
by a telescope equipped with a digital
imaging eyepiece and a small television screen.
APOD: 2003 June 3 - The Milky Way Behind an Eclipsed Moon
Explanation:
What's behind the Moon? Each month,
our Moon passes in front of --
and outshines -- many an interesting star field.
Exceptions occur during a
new Moon and during a
total eclipse.
In the background of a new
Moon
is usually the Sun, an even brighter orb that even
more easily outshines everything behind it, except during a
total solar eclipse.
Even the longest total solar eclipse
lasts just a few minutes, while the
Sun's corona still remains bright.
During a total lunar eclipse,
however, the full Moon
dims and a majestic star field may present itself for an hour or more.
Such was the case during the middle of last month,
when a rare glimpse of an eclipsed Moon superposed in front of the disk of our home
Milky Way Galaxy was captured.
Although fully in the Earth's shadow, the eclipsed Moon is still the
brightest object on the right.
The above image was captured during sub-zero weather from the
Teide 2003 expedition to
Mirador del Pico Viejo, a mountain in the
Canary Islands,
Spain, off the northwest coast of
Africa.
APOD: 2003 May 21 - Copper Moon, Golden Gate
Explanation:
When the Moon rose over
San Francisco's Golden
Gate Bridge on May 15, both bridge and Moon were in already
in Earth's shadow.
Of course, the bridge is in the Earth's shadow nightly, while
the Moon only has that opportunity
about
twice a year, during a lunar eclipse.
And even though in western North America the total phase of the lunar
eclipse began before moonrise, many in areas with clear skies came out
to enjoy the spectacle.
For this eclipse, skygazers reported a darker than normal,
copper-colored
Moon during totality.
The dramatic color is evident in this multiple exposure of the
reddened Moon
rising, taken by astrophotographer Evad Damast.
Damast viewed the eclipse from the Marin Headlands north and west of
the famous
bridge, looking back toward the bay and the city
lights.
APOD: 2003 April 21 - A Halo Around the Moon
Explanation:
Have you ever seen a halo around the Moon?
This fairly common sight occurs when high thin clouds containing millions of tiny
ice crystals cover much of the sky.
Each
ice crystal acts like a miniature lens.
Because
most of the crystals have a similar
elongated hexagonal shape,
light entering one crystal face and exiting
through the opposing face refracts 22
degrees,
which corresponds to the radius of the Moon Halo.
A similar Sun Halo
may be visible during the day.
The picture was taken in Lansdowne,
Pennsylvania,
USA.
The distant planet
Jupiter
appears by chance just to the left of the
Moon.
Exactly how
ice-crystals form in clouds remains under
investigation.
APOD: 2002 September 14 - X-Ray Moon
Explanation:
This x-ray image of the Moon
was made by the orbiting
ROSAT
(Röntgensatellit) Observatory in 1990.
In this digital picture, pixel brightness corresponds to x-ray intensity.
Consider the image in three parts:
the bright hemisphere of the x-ray moon,
the darker half of the moon,
and the x-ray sky background.
The bright lunar hemisphere shines
in x-rays because it scatters
x-rays emitted by the sun.
The background sky has an x-ray
glow in part due to
the myriad of distant, powerful active galaxies, unresolved
in the ROSAT picture but recently detected in Chandra Observatory
x-ray images.
But why isn't the dark half of the moon completely dark?
It's true that the dark lunar face is in
shadow and so is shielded
from direct solar x-rays.
Still, the few x-ray photons which seem to come from the moon's
dark half are currently thought to be caused by energetic particles in
the
solar wind bombarding the lunar surface.
APOD: 2002 April 19 - The Old Moon in the New Moon's Arms
Explanation:
Also known as the Moon's "ashen glow" or
"the old Moon in the new Moon's arms",
Earthshine is
Earthlight reflected from the Moon's night side.
This dramatic image
of Earthshine and a young crescent
Moon was taken by
astrophotographer and
APOD translator
Laurent Laveder from the remote
Pic du
Midi Observatory on planet Earth.
But the
view
from the Moon would have been stunning too.
When the Moon appears in Earth's sky as a slender crescent,
a dazzlingly bright, nearly full Earth would be seen
from the lunar surface.
The Earth's brightness, due to reflected sunlight,
is strongly influenced by cloud cover and
recent studies
of Earthshine indicate that it is more pronounced
during April and May.
A description of Earthshine, in
terms of sunlight reflected by Earth's oceans in turn illuminating
the Moon's dark surface, was written 500 years ago by
Leonardo
da Vinci.
APOD: 2002 February 9 - Moon Over Mongolia
Explanation:
Fighting clouds and the glow of city lights,
a young Moon shines over the western horizon of
Mongolia's capital,
Ulaan-Baatar.
The thin
sunlit
crescent is about 2 days old and strongly over exposed in this
image taken on March 10, 1997.
The night side of the Moon is also visible due to
earthshine -
sunlight reflected from the Earth to the Moon.
Just below the Moon,
bright Saturn shines through the clouds.
Skygazers
will have a chance to watch the Moon actually
pass in front of the
ringed planet in February, March, and April
this year.
In fact, an excellent lunar occultation of Saturn will
be visible from parts of North America
on February 20th
as Saturn disappears behind the dark limb of a first quarter
Moon.
Some may even take this opportunity to search for
Saturn's lost ring.
APOD: 2001 September 6 - Moon AND Stars
Explanation:
Here's something you don't see too often ... a detailed picture of the
full Moon surrounded by a rich field of background stars.
It's true that bright moonlight scattered by the atmosphere tends to
mask faint stars, but pictures of the
sunlit portion
of the Moon made
with earthbound telescopes
or even with cameras on the
lunar surface often
fail to show any background
stars at all.
Why? Because the exposure times are too short.
Very short exposures, lasting fractions of a second, are required to
accurately
record
an image of the bright lunar surface.
But the background stars (and galaxies!) such as those visible above
are much fainter and need exposures lasting minutes to hours which
would seriously overexpose
the surface of the Moon.
So, of course this stunning view
really is a combination of two digital images --
a short exposure, registering the exquisite lunar
surface details
at full Moon, superposed on
a separate very long exposure, made with
the Moon absent from the star field.
The final representation
of
Moon and background stars is very
dramatic, even though it could not have been captured in a single
exposure.
APOD: 2001 July 13 - Welcome to the Moon Hotel
Explanation:
The most detailed proposal
so far for a hotel and resort destination
on the Moon (!) has been prepared by
Dutch
architect Hans-Jurgen Rombaut.
The harsh
lunar environment
posed serious
design challenges but the Moon's low,
one-sixth-Earth gravity,
and the absence of wind were an
architectural boon allowing a much more slender and fragile-looking
building than would have been
possible on Earth.
Illustrated here, the structure's two 160 meter high needle-like
towers soar over
the rim of a deep canyon as planet Earth hangs in the
lunar sky.
To shield the interior, Rombaut designed 50 centimeter thick walls
with two outer layers of Moon rock and a 35
centimeter layer of
water
held between glass planes.
The water absorbs energetic cosmic rays and along with the
rock helps keep the temperature constant.
Windows are framed as holes in the rock layers.
Construction
materials are intended to be manufactured
on the Moon itself.
This Moon Hotel design is welcomed by the international Lunar
Explorers Society, LUNEX,
who hope to construct a robotic
Moon base by 2015,
ultimately
supporting a lunar village by 2040.
APOD: 2001 February 19 - Shuttle Plume Shadow Points to Moon
Explanation:
Why would the shadow of a
space shuttle
launch plume point toward the Moon?
Two weeks ago during the launch of
Atlantis, the
Sun,
Earth,
Moon,
and rocket were all properly aligned for
this photogenic coincidence.
First, for the
space shuttle's plume to cast a long shadow,
the time of day must be either near
sunrise or
sunset.
Next, just at sunset, the
shadow
is the longest and extends all the way to the
horizon.
Finally, during a
Full Moon, the
Sun and
Moon are on
opposite sides of the sky.
Just after
sunset, for example,
the Sun is slightly below the
horizon, and,
in the other direction,
the Moon is slightly above the
horizon.
Therefore, as
Atlantis blasted off, just after
sunset,
its shadow projected away from the Sun
toward the opposite horizon, where the
Full Moon just happened to be.
APOD: 2000 October 13 - Eclipse Moon Trail
Explanation:
Tonight, Friday the 13th, October's big, bright, beautiful
full Moon
will be in the sky, rising as the sun sets.
A time exposure of this evening's full Moon would show a brilliant
circular arc or Moon trail tracing its celestial path.
In fact, this single,
four hour long exposure from the
evening of January 20 shows a full Moon trailing
through hazy
skies above Phoenix, Arizona, USA.
Of course, the picture also shows something you won't see
tonight -- a total
lunar eclipse.
A lunar eclipse is caused when
the full moon enters
Earth's
shadow and
as the eclipsed Moon's light grows steadily
fainter, the Moon trail becomes narrow and dim.
The total eclipse phase, when the Moon passes completely within
Earth's shadow,
occurs near the middle of this Moon
trail arc.
But even during totality, the Moon trail is visible and noticeably red.
Normally illuminated by sunlight which falls directly on
its surface, during a total
lunar eclipse the Moon is still illuminated
by sunlight filtered and refracted through Earth's atmosphere.
The refracted light lends the
eclipsed Moon a dim
and reddish appearance.
APOD: 2000 September 2 - X Ray Moon
Explanation:
This x-ray image of the Moon
was made by the orbiting
ROSAT
(Röntgensatellit) Observatory in 1990.
In this digital picture, pixel brightness corresponds to x-ray intensity.
Consider the image in three parts:
the bright hemisphere of the x-ray moon,
the darker half of the moon,
and the x-ray sky background.
The bright lunar hemisphere shines
in x-rays because it reflects
x-rays emitted by the sun ... just as it shines
at night by reflecting visible sunlight.
The background sky has an x-ray
glow in part due to
the myriad of distant, powerful active galaxies, unresolved
in the ROSAT picture but recently detected in Chandra Observatory
x-ray images.
But why isn't the dark half of the moon completely dark?
It's true that the dark lunar face is in
shadow and so is not
reflecting solar x-rays.
Still, the few x-ray photons which seem to come from the moon's
dark half are currently thought to be caused by energetic particles in
the
solar wind bombarding the lunar surface.
APOD: 2000 July 28 - Moon And Venus Share The Sky
Explanation:
July is drawing to a close and in the past few days,
some early morning risers could have
looked east and seen a crescent Moon
sharing the pre-dawn skies with planets Jupiter and Saturn.
Planet Mercury will also pass
about 2 degrees from
the thin waning crescent
Moon
just before sunrise near the eastern horizon
on Saturday, July 29.
And finally, on the evening of July 31st, Venus will take its turn
near the crescent Moon.
But this time it will be a day-old crescent Moon near the western horizon,
shortly after sunset.
In
fact, on July 31 (August 1 Universal Time)
the Moon will occult
(pass in front of) Venus for
northwestern observers in North America.
This telescopic picture taken on 31 December 1997, shows a lovely young
crescent Moon and brilliant crescent
Venus in the early evening sky near
Bursa,
Turkey.
And what about the Sun? On Sunday, July 30, a
partial eclipse of the Sun will be visible from
some locations in North America.
APOD: 2000 June 17 - The Last Moon Shot
Explanation:
In 1865 Jules Verne predicted the invention of a space capsule that
could carry people.
In his science fiction story
"From the Earth to the Moon", he outlined his vision of
a cannon in Florida so powerful that it could shoot a
"Projectile-Vehicle" carrying three adventurers
to the Moon.
Over 100 years later,
NASA, guided by
Wernher Von Braun's vision, produced the
Saturn V rocket.
From a
spaceport in Florida,
this rocket turned Verne's fiction into fact,
launching 9 Apollo Lunar missions and
allowing 12 astronauts to walk on the Moon.
Pictured is the last moon shot,
Apollo 17, awaiting a night launch in December of 1972.
Spotlights play on the rocket and launch pad
while the full Moon looms
in the background.
Humans have not
walked on on the lunar surface
since.
APOD: 2000 April 6 - Venus, Moon, and Neighbors
Explanation:
Rising before the Sun on February 2nd,
astrophotographer Joe Orman
anticipated this apparition of the bright
morning star
Venus near a lovely crescent Moon above a neighbor's house
in suburban Phoenix, Arizona, USA.
Fortunately, the alignment of bright planets and the Moon is
one of the most inspiring sights in the
night sky and one
that is often easy to enjoy and share without any special equipment.
Take tonight, for example.
Those blessed with clear skies can simply step
outside near sunset
and view a young crescent Moon very near three bright planets
in the west
Jupiter,
Mars, and
Saturn.
Jupiter will be the unmistakable brightest star near the Moon
with a reddish Mars just to Jupiter's north and pale yellow
Saturn directly above.
Of course, these
sky
shows create an
evocative picture but the
planets and Moon just appear to be near each other --
they are actually only approximately lined up and
lie in widely separated orbits.
Unfortunately, next month's highly publicized
alignment of planets on May 5th will be lost from
view in the Sun's glare but such
planetary
alignments occur repeatedly and
pose no danger to planet Earth.
APOD: 2000 January 13 - A Skygazers Full Moon
Explanation:
This dramatically sharp picture of the full moon was
recorded on 22 December, 1999 by astroimager
Rob Gendler.
Big, beautiful, bright, and
evocative, it was the last
full moon of the Y1.9Ks, pleasing and inspiring even
casual skygazers.
December's
moon was special for another reason, as
the full
phase
occurred on the day of the winter solstice and within hours
of lunar perigee.
The first full moon of the year 2000 will bring
a special treat
as well, presenting denizens of planet Earth with
a total lunar eclipse.
On Thursday evening, January 20, the
moon will encounter the dark edge of Earth's shadow at 10:01 PM
Eastern Time
with the total eclipse phase beginning at 11:05 PM
and lasting for 77 minutes.
This lunar eclipse will be visible from North and South America and
Western Europe (total phase begins at 4:05 AM GMT January 21).
APOD: December 22, 1999 - Perigee Moon, Apogee Moon
Explanation:
Tonight, those blessed with clear skies can enjoy a
glorious full moon,
the last full moon of the "Y1.9K"s.
In fact, tonight's moon will be a full-perigee-solstice moon,
reaching its full phase and perigee (the closest point in
its orbit)
on the solstice,
the first day of northern hemisphere winter.
Anticipation of this celestial event has generated
a flood of e-mail chasing the rumor
that the full-perigee-solstice moon will be intensely bright.
However, calculations show it will only be a little brighter than usual,
and certainly not dramatically so.
Why would it be brighter?
Mostly because the moon appears bigger and brighter at perigee.
The above illustration, based on
Galileo spacecraft images,
shows the approximate difference in apparent
size between a
full moon
at perigee (left) and a full moon at apogee,
the farthest point in the lunar orbit.
The Earth and moon are also a few percent closer to the sun
during northern winter,
but the combined effects will cause tonight's full moon to appear
only about 20% brighter than an average full moon.
That difference is not even likely to be noticeable to
the human eye.
APOD: December 8, 1999 - Moon Struck
Explanation:
Craters produced by ancient impacts on the
airless Moon have long been a
familiar sight.
But now observers have seen elusive
optical flashes on the lunar surface -
likely the fleeting result of impacting meteoroids.
Orchestrated by David Dunham, president of the
International Occultation Timing Association (IOTA),
video recordings made with modest equipment and
visual telescopic observations have, for the first time,
detected and confirmed a total of six flashes on the Moon's dark side.
The flashes,
some initially as bright as a third magnitude star,
were all seen within hours of the peak of this year's
Leonid meteor shower.
Their locations are indicated by the red Xs on this
projection of the Moon as it appeared on the night of November 18.
Similar flashes would have been difficult to see if
viewed against the Moon's brightly lit portion.
It has been estimated that the brightest flashes were made by
meteoroids weighing around a tenth of a kilogram, resulting
in lunar craters about one meter across.
And ... the
next chance to observe lunar impact flashes
is coming up!
Enterprising astronomers interested in long distance
lunar prospecting
should be monitoring the dark side of
a nearly first quarter Moon during the
Geminids meteor shower which will peak
around December 13.
APOD: October 15, 1999 - Moon Crashers
Explanation:
On July 31, 1964,
Ranger 7 crashed into the Moon.
Seventeen minutes
before impact it snapped this picture -
the first image of the Moon ever taken by a U.S. spacecraft.
Of course Ranger 7 was intended to crash,
transmitting close-up pictures of the lunar surface
during its final moments.
The Ranger program's goal was to begin high resolution mapping of the
lunar surface in preparation for a future
lunar landing.
This first image covered 360 kilometers from top to bottom and
is centered in the
Mare Nubium (Sea of Clouds).
The large crater at middle right,
Alphonsus,
is 108 kilometers in diameter.
On July 31, 1999,
Lunar Prospector crashed into the Moon.
During its successful 1 year mission to map the Moon's
global properties from orbit,
Lunar Prospector confirmed indications that
water-ice could be trapped in permanently shadowed craters near the
lunar poles.
Its mission complete, controllers
intentionally targeted the
spacecraft to impact a crater wall, hoping that water could
be more directly detected in the resulting debris cloud - although
the chances of a successful detection were considered low.
Astronomers
analyzing the data
recently announced
that no visible signature of water was found, so the tantalizing case for
water on the Moon remains open.
APOD: October 14, 1999 - Moon Over Eugenia
Explanation:
Eugenia is an
asteroid with a moon!
This animation was constructed from infrared discovery images of the
Eugenia-moon system taken in November 1998 using the
Canada-France-Hawaii Telescope (CFHT).
Main belt asteroid Eugenia, represented here as a central white patch,
is a mere 215 kilometers in diameter.
Its moon, seen at 5 separate positions around a clockwise orbit,
is estimated to be 13 kilometers wide.
An adaptive optics system was used with the CFHT,
located atop Mauna Kea, Hawaii,
to counteract the blurring effect of Earth's atmosphere making possible
this premier discovery from a ground-based
telescope.
Only one
other asteroid-moon system is known.
Dactyl, moon of the asteroid Ida, was discovered by the
Galileo spacecraft during a 1993 flyby.
Eugenia's moon has a nearly circular orbit with a radius of
1,190 kilometers which it completes once in 4.7 days.
The orbit appears oval-shaped because it is tilted
at a 45 degree angle to the line-of-sight.
Knowing the moon's orbit allows astronomers
to calculate the asteroid's mass.
Combining mass and size determines the asteroid's density,
which in this case gives a surprising result -
Eugenia is found to have a density only 20% greater than water.
The low density suggests that Eugenia itself is a porous "rubble pile"
of rocks or composed mostly of water-ice with only a little
additional rocky material.
APOD: May 31, 1999 - Uranus Moon 18
Explanation:
The discovery was there for the taking. An image of
Uranus taken by
Voyager 2 as it passed the giant planet
13 years ago apparently recorded a moon
that had since gone unnoticed.
The image on which Uranus' 18th moon was discovered was
freely available from NASA.
Erich Karkoschka
(U. Arizona)
noticed the moon when comparing a 1986 photo to a
recent one taken by the
Hubble Space Telescope.
The newly identified moon is hard to see but marked in the
above photograph. Also visible are many other Uranian moons and background stars.
The moon is the 18th known around Uranus, tying it with Saturn for the most around any planet.
APOD: April 19, 1999 - The Full Moon
Explanation:
Earth has one moon. A symbol in famous
love songs,
movies, poems, and
folklore, many
myths about the
Moon date back to ancient history.
In fact, the name
Monday originates from Moon-day.
The Moon glows by light it reflects from the
Sun and is frequently the brightest object in the night sky.
The
Moon orbits the Earth about once a month (moon-th)
from about 1 light second away. The
above-pictured Full Moon occurs when the Moon
is nearly opposite to the Sun in its orbit.
The Moon's diameter is about 1/4 that of the
Earth, and from the
Earth's surface appears to have almost exactly
the same angular size as the Sun. Recent
evidence indicates that the
Moon formed from a colossal impact on the
Earth
about 4.5 billions of years ago, and therefore has a
similar composition to the Earth.
Humans walked on the Moon
for the first time in 1969.
APOD: March 26, 1999 - Impact Moon
Explanation:
The Moon's surface is covered with craters, scars of
frequent impacts during the early history of the solar system.
Now, recent results from the
Lunar Prospector spacecraft support
the idea that the Moon itself formed from the debris of a giant impact of
a mars-sized planetary body with the Earth nearly 4.5 billion years ago.
The impact theory of lunar origin
can explain, for example, why Moon rocks returned by the
Apollo missions
have the same isotopic ratios as Earth rocks while the Moon seems
deficient in heavy elements like iron.
It can also explain
a critical finding of the Lunar Prospector experiments - that
the Moon's core is proportionally very small.
If the Moon formed simply as a "sister world", its origin paralleling
Earth's formation from the primordial
solar nebula, it should
have similar iron content and relative core size.
But material blasted from the surface of Earth by an impacting
body would lack the iron and heavy elements which had settled
to the Earth's core yet retain similar ratios of
chemical isotopes.
A fraction of this debris cloud would remain in Earth orbit ultimately
forming the Moon.
APOD: January 29, 1999 - The Moon In January
Explanation:
Reckoning dates by Universal Time,
the next full moon will
be on Sunday, January 31.
Since the last was on January 2nd, Sunday's full moon will be
the second this month.
Perhaps only in recent times,
the term "Blue Moon" has come
to mean the second full moon in a month, joining a
list of folklore names for the brightest lunar phase.
Aren't Blue Moons extremely rare?
Well, the moon's phases repeat every 29.5 days and most
months have 30 or 31 days, so a Blue Moon is certainly
possible if not a common event.
In fact, the next (and last) Blue Moon in 1999 will occur in March,
leaving February without a full moon at all.
This sharp telescopic view of a waning crescent moon was recorded
on January 12th by the European Southern Observatory's new
WFI camera.
APOD: December 13, 1998 - Blasting Off from the Moon
Explanation:
How did the
astronauts
get back from the
Moon? The
Lunar Module
that landed two astronauts on the Moon actually came apart. The top part
containing the astronauts carried additional rocket fuel which allowed it
to blast away, leaving the bottom part on the Moon forever. The top part
would later meet up with the
Command
Module and its astronaut pilot, which
were continually orbiting the Moon. All would then return to Earth
together. The
above
picture was taken by a robot TV camera left on the Moon
by the crew of
Apollo 16.
The frame above captures the top part of the
Lunar Module just at it was blasting off.
APOD: May 3, 1998 - Standing on the Moon
Explanation:
Humans once walked on the Moon. Pictured
above is the second person to stand on the lunar surface: Edwin
"Buzz" Aldrin. During this Apollo 11
mission, Neil Armstrong
(the first person to walk on the moon) and Buzz Aldrin
landed on the Moon while Michael Collins
circled in the Command Module
above. The lunar team
erected a plaque on the surface that reads: HERE MEN FROM THE
PLANET EARTH FIRST SET FOOT UPON THE MOON JULY 1969 A.D. WE CAME
IN PEACE FOR ALL MANKIND. The
Apollo missions demonstrated that
it is possible to land humans on the Moon
and return them safely.
APOD: January 29, 1998 - The Earth-Moon System
Explanation:
This evocative mosaic image of
the Earth-Moon system was recorded by
NASA's Near Earth Asteroid Rendezvous (NEAR) spacecraft earlier this month.
The relative sizes shown are appropriate for viewing both
the Earth and
Moon
from a distance of about 250,000 miles, although the apparent
brightness of the Moon has been increased by about a factor
of five for the sake of appearances.
This space-based perspective is a unique one,
the bland and somber
Lunar Southern Hemisphere
contrasting strongly with blue oceans,
swirling clouds, and the bright icy white continent
of Antarctica on planet Earth.
Though its lack of
atmosphere
and oceans
make it relatively dull looking,
the Earth's moon is one of
the largest moons in the solar system
- even larger than the planet
Pluto.
During this
recent flyby of the Earth-Moon system,
the NEAR spacecraft
used Earth's gravity to deflect it towards its ultimate destination,
the Asteroid 433 Eros.
It is scheduled to arrive at Eros in January 1999.
APOD: January 3, 1998 - The Barren Moon
Explanation:
The above photo, taken as the
Apollo 17 astronauts orbited the Moon
in 1972, depicts the stark lunar surface around
the Eratosthenes and Copernicus craters.
Many similar images of a Moon devoid of life are
familiar to denizens of the space age.
Contrary to this modern perception,
life on the Moon was reported in August of 1835
in a series of sensational stories first published by the New York Sun
- apparently intended to improve the paper's circulation.
These descriptions of lunar life received broad credence and
became one of the most spectacular
hoaxes in history.
Supposedly based on telescopic observations,
the stories featured full, lavish
accounts of a Moon with oceans and beaches, teeming with plant
and animal life and climaxing
with the report of sightings of groups of
winged, furry, human-like creatures resembling bats!
Within a month the hoax had been revealed
but the newspaper continued to enjoy an increased readership.
Though barren,
the Moon remains a popular setting for
science fiction stories and extra-terrestrial adventures.
It has now been
25 years since Apollo 17 ended an era of
human exploration of Earth's Moon.
APOD: September 16, 1997 - Moon Over Mongolia
Explanation:
Fighting clouds and the glow of city lights,
a young Moon shines over the western horizon of
Mongolia's
capital Ulaan-Baatar.
The thin sunlit crescent is 1.5 days old and strongly over exposed in this
image taken on March 10.
The night side of
the moon is also visible due to
Earthshine - sunlight reflected from the Earth
to the Moon.
Just below
the Moon,
bright Saturn shines through the clouds.
Early morning risers can see the Moon near Saturn
this week.
In fact, from North America the Moon can be seen
to pass in front of the ringed planet
on Thursday morning, September 18th.
APOD: June 7, 1997 - Apollo 15: Driving on the Moon
Explanation:
Apollo 15
astronaut James Irwin works on the first
Lunar Roving Vehicle,
before he and fellow astronaut
David
Scott take it out for a drive.
Sloping up behind the
lunar module
"Falcon" on the left are lunar mountains
Hadley Delta and Apennine Front,
while about 5 kilometers behind Irwin is
St. George Crater. The explorations conducted during the
Apollo lunar missions
discovered much about our Moon,
including that the
Moon is made of ancient rock, that the
Moon's
composition is similar to
Earth's, that life is not
evident there, that the Moon underwent a great hot melting in its distant
past, that the Moon has suffered from numerous impacts as shown by its
craters, and that the
Moon's surface is covered by a layer of rock
fragments and dust.
APOD: May 4, 1997 - The Last Moon Shot
Explanation:
In 1865
Jules Verne predicted the invention of a space capsule that
could carry people.
In his science fiction story
"From the Earth to the Moon", he outlined his vision of
a cannon in Florida so powerful that it could shoot a
"Projectile-Vehicle" carrying
three adventurers to the Moon.
Over 100 years later,
NASA, guided by
Wernher Von Braun's vision, produced the
Saturn V rocket.
From a
spaceport in Florida,
this rocket turned Verne's fiction into fact,
launching 9 Apollo Lunar missions and
allowing 12 astronauts to walk on the Moon.
Pictured is the last moon shot,
Apollo 17, awaiting a night launch in December of 1972.
Spotlights play on the rocket and launch pad
while the full Moon looms
in the background.
Humans have not walked on the lunar surface since.
Should we return to the Moon?
APOD: July 31, 1996 - A Violet Moon
Explanation:
Checking out the Galileo
spacecraft's cameras during its December 1992 flyby
of Earth's Moon, controllers took
this dramatically illuminated picture
through a violet filter.
The view looks down on the Moon's north polar
region with
the Sun shining from the left at a low angle and
the direction toward the moon's North pole toward the lower right.
Across the image upper left stretches
the smooth volcanic plain
of the Mare Imbrium.
Pythagoras crater, 65 miles wide, is near the
center of the image -- mostly in shadow, its central peak just
catches the sunlight.
Yesterday, the Moon made its closest approach to Earth and was
full for the second time in July
(as reckoned by UT dates). The closest
point in the Moon's orbit is referred to as Lunar Perigee, a mere
221,797 miles at 8 hours UT. The second full moon in a month is known as
a "Blue Moon".
APOD: July 30, 1996 - Tonight: A Blue Moon
Explanation:
How often does a Full Moon occur twice in a single month? Exactly once in a
Blue Moon. In fact, the modern usage of the term
"Blue
Moon" refers to the second Full Moon in a single month. Tonight's
Blue
Moon
(Universal Time)
will be the first since September 1993.
A Blue
Moon typically occurs every few years.
The reason for the rarity of the
Blue Moon
is that the 29.53 days between full moons is
just slightly shorter than the number of days in the average month.
Don't, however, expect the moon to look blue tonight!
The
term "Blue Moon"
is thought to derive from common language expressions used hundreds of
years ago. It is possible for the Moon to appear tinged by a blue hue,
sometimes caused by fine dirt circulating in the Earth's
atmosphere, possibly from a volcanic explosion.
The above picture is of our
Moon taken was taken in a dark blue morning
sky. The bright crescent is the only part directly exposed to sunlight -
the rest of the
Moon glows from
sunlight reflected from the
Earth. In
this dramatic
photo, however, the planet
Jupiter is also visible along with its
four largest moons.
APOD: June 9, 1996 - Blasting Off From the Moon
Explanation:
How did the
astronauts
get back from the
Moon? The
Lunar Module
that landed two astronauts on the Moon actually came apart. The top part
containing the astronauts carried additional rocket fuel which allowed it
to blast away, leaving the bottom part on the Moon forever. The top part
would later meet up with the
Command
Module and its astronaut pilot, which
were continually orbiting the Moon. All would then return to Earth
together. The
above
picture was taken by a robot TV camera left on the Moon
by the crew of
Apollo 16.
The frame above captures the top part of the
Lunar Module just at it was blasting off.
APOD: February 23, 1996 - Apollo 15: Driving on the Moon
Explanation:
Apollo 15
astronaut
James
Irwin works on the first
Lunar Roving Vehicle,
before he and fellow astronaut
David
Scott take it out for a drive.
Sloping up behind the
lunar module
"Falcon" on the left are lunar mountains
Hadley Delta and Apennine Front,
while about 5 kilometers behind Irwin is
St. George Crater. The explorations conducted during the
Apollo lunar missions
discovered much about our Moon,
including that the Moon is made of ancient rock, that the Moon's
composition is similar to Earth's, that life is not
evident there, that the Moon underwent a great hot melting in its distant
past, that the Moon has suffered from numerous impacts as shown by its
craters, and that the Moon's surface is covered by a layer of rock
fragments and dust.
APOD: September 9, 1995 - The Last Moon Shot
Explanation:
In 1865 Jules Verne predicted the invention of a space capsule that
could carry people. In his science fiction story
"From the Earth to the Moon", he outlined his vision of constructing
a cannon in Florida
so powerful that it could shoot a "Projectile-Vehicle"
carrying three adventurers to the Moon. Over 100 years later, NASA, guided by
Wernher Von Braun's vision, produced the
Saturn V rocket. This rocket
turned Verne's fiction into fact,
launching 9 Apollo Lunar missions and allowing 12 astronauts
to walk on the Moon. Pictured above is the last moon shot,
Apollo 17, awaiting a night launch in December of 1972.
Spot lights play on the rocket and launch pad
while the full Moon looms in the background.
Humans have not walked on the lunar surface since.
Should we
return to the Moon?
APOD: September 3, 1995 - Earth's Moon, A Familiar Face
Explanation:
The above mosaic of the Earth's
Moon was compiled from photos taken by the spacecraft
Clementine
in 1994. This image represents the side of the Moon familiar to Earth dwellers.
The
Moon
revolves around the
Earth about once every 28 days. Since its rate of rotation about its
axis is also once in 28 days, it always keeps the same face toward
the Earth. As the Moon travels around its orbit, the Earth based view
of the half of the
Moon that faces the
Sun changes causing the regular monthly progression
of Lunar phases.
Humans first crashed a
spacecraft into the Moon
in 1959, but the first humans to reach the Moon
landed in 1969. There are now
golf
balls on the Moon.