Astronomy Picture of the Day |
APOD: 2024 February 14 – Rosette Deep Field
Explanation:
Can you find the Rosette Nebula?
The large, red,
and flowery-looking nebula on the upper left
may seem the obvious choice, but that is actually just diffuse
hydrogen emission surrounding the
Cone and Fox Fur Nebulas.
The famous Rosette Nebula is really located on the lower right and connected to the
other nebulas by irregular filaments.
Because the
featured image of Rosetta's field is so
wide and deep,
it seems to contain other flowers.
Designated NGC 2237, the center of the Rosette nebula is populated by the bright blue stars of open cluster
NGC 2244,
whose winds and
energetic light are evacuating the nebula's center.
The Rosette Nebula is about 5,000 light years distant and, just by itself,
spans about three times the diameter of a
full moon.
This flowery field can be found toward the
constellation of the
Unicorn
(Monoceros).
APOD: 2024 January 29 – The Pleiades: Seven Dusty Sisters
Explanation:
The well-known Pleiades star cluster is slowly
destroying part of a passing cloud of gas and dust.
The Pleiades
is the brightest
open cluster of stars
on Earth's sky and
can be seen
from almost any northerly location with the
unaided eye.
Over the past 100,000 years, a field of gas and dust
is moving by chance right through the
Pleiades star cluster and is causing
a strong reaction between the
stars and dust.
The passing cloud might be part of the
Radcliffe wave, a
newly discovered
structure of gas and dust connecting several regions of
star formation in the
nearby part of our
Milky Way galaxy.
Pressure from the stars' light significantly repels
the dust in the surrounding blue
reflection nebula, with
smaller dust particles being repelled more strongly.
A short-term result is that parts of the dust cloud have become
filamentary and
stratified.
The featured deep image incorporates
nearly 9 hours of exposure and was captured from
Utah Desert Remote Observatory in
Utah,
USA, last year.
APOD: 2024 January 3 – A SAR Arc from New Zealand
Explanation:
What is that unusual red halo surrounding this aurora?
It is a Stable Auroral Red (SAR) arc.
SAR arcs are rare and have only been acknowledged and studied since 1954.
The featured wide-angle photograph,
capturing nearly an entire
SAR arc
surrounding more common green and red aurora,
was taken earlier this month from
Poolburn,
New Zealand, during an especially energetic
geomagnetic storm.
Why SAR arcs form remains a topic of
research, but is likely related to
Earth's protective magnetic field, a field created by
molten iron
flowing deep inside the
Earth.
This magnetic field usually redirects incoming charged particles from the
Sun's wind toward the Earth's poles.
However, it also traps a
ring of ions
closer to the equator, where they can gain energy from the
magnetosphere during high
solar activity.
The energetic electrons in this
ion ring can collide with
and excite oxygen higher in
Earth's ionosphere than typical
auroras, causing the oxygen to glow red.
Ongoing research has uncovered evidence that a red SAR arc
can even transform into a
purple and green
STEVE.
APOD: 2023 December 13 – Deep Field: The Heart Nebula
Explanation:
What excites the Heart Nebula?
First, the large emission nebula
on the left, catalogued as
IC 1805, looks somewhat like a human heart.
The nebula glows brightly in red light
emitted by its
most prominent element,
hydrogen,
but this long-exposure image was also blended with light
emitted by silicon (yellow) and oxygen (blue).
In the center of the
Heart Nebula are young stars from the open star cluster
Melotte 15
that are eroding away several picturesque
dust pillars with their atom-exciting
energetic light and winds.
The Heart Nebula is located about 7,500 light years away toward the
constellation
of Cassiopeia.
At the bottom right of the Heart Nebula is the companion
Fishhead Nebula.
This wide and deep image clearly shows, though,
that glowing gas surrounds the Heart Nebula in all directions.
APOD: 2023 July 21 - Galactic Cirrus: Mandel Wilson 9
Explanation:
The combined light of
stars along the Milky Way
are reflected by these cosmic dust clouds that soar
300 light-years or so above the plane of our galaxy.
Known to some as integrated flux nebulae and
commonly found
at high galactic latitudes, the dusty
galactic cirrus
clouds are faint.
But they can be traced over large regions of the sky
toward the North and South Galactic poles.
Along with the reflection of starlight, studies indicate
the dust clouds produce a
faint reddish luminescence
as interstellar dust grains
convert invisible ultraviolet radiation to visible red light.
Also capturing nearby Milky Way stars and
distant background galaxies,
this remarkably deep, wide-field image
explores a complex of faint galactic cirrus known as Mandel Wilson 9.
It spans over three degrees across planet Earth's skies toward
the far southern constellation Apus.
APOD: 2023 July 15 - Webb's First Deep Field
Explanation:
This stunning infrared image
was released
one year ago
as the James Webb Space Telescope began its exploration of the cosmos.
The view
of the
early Universe
toward the southern constellation Volans
was achieved in 12.5 hours of exposure with Webb's NIRCam instrument.
Of course the stars with six spikes are well within our own
Milky Way.
Their diffraction
pattern is characteristic of Webb's 18 hexagonal mirror
segments operating together as a single 6.5 meter diameter primary
mirror.
The thousands of galaxies flooding the field of view are members of the
distant galaxy cluster SMACS0723-73, some 4.6 billion light-years away.
Luminous arcs that seem to infest the deep field are
even more distant galaxies though.
Their images are distorted and magnified by the
dark matter dominated mass of the galaxy cluster, an effect
known as gravitational lensing.
Analyzing light
from two separate arcs below the bright spiky star,
Webb's NIRISS instrument indicates the arcs
are both images of the same background galaxy.
And that galaxy's light took about 9.5 billion years to reach the
James Webb Space Telescope.
APOD: 2023 July 1 - Three Galaxies in Draco
Explanation:
This tantalizing trio of galaxies sometimes called the Draco Group,
is located in the northern constellation of (you guessed it)
Draco, the Dragon.
From left to right are
face-on spiral NGC 5985,
elliptical galaxy NGC 5982, and
edge-on spiral NGC 5981,
all found within this
single telescopic field of view that spans a little more than
the width of the full moon.
While the group is far too small to be a
galaxy cluster,
and has not been
catalogued
as a compact galaxy group,
the three galaxies all do lie roughly
100 million light-years from planet Earth.
Not as well known as other tight
groupings of galaxies,
the contrast in visual appearance
still makes this triplet an attractive subject for astroimagers.
On close examination with
spectrographs,
the bright core of striking spiral NGC 5985 shows
prominent emission in specific wavelengths of light, prompting
astronomers to classify it as a
Seyfert, a type of active galaxy.
This
impressively deep exposure
hints at a faint dim halo along with sharp-edged shells surrounding
elliptical NGC 5982, evidence of past galactic mergers.
It also reveals many even more
distant background galaxies.
APOD: 2023 June 28 - Messier 24: Sagittarius Star Cloud
Explanation:
Unlike most entries
in Charles Messier's famous catalog of deep sky objects,
M24
is not a bright galaxy, star cluster, or nebula.
It's a gap in nearby, obscuring interstellar dust clouds that allows
a view of the distant stars in the Sagittarius spiral arm
of our Milky Way galaxy.
Direct your gaze
through this gap with binoculars or small telescope
and you are
looking through a window over 300 light-years wide at stars some
10,000 light-years or more from Earth.
Sometimes called the Small Sagittarius Star Cloud, M24's luminous stars fill
this gorgeous starscape.
Covering over 3 degrees or the width of 6 full moons in the
constellation Sagittarius,
the telescopic field of view includes
dark markings
B92 and B93 near center, along with other
clouds of dust and glowing nebulae toward the center of the Milky Way.
APOD: 2023 June 9 - Pandora's Cluster of Galaxies
Explanation:
This deep field mosaicked image
presents a stunning view of galaxy cluster Abell 2744 recorded by
the James Webb Space Telescope's NIRCam.
Also dubbed Pandora's Cluster, Abell 2744 itself
appears to be a ponderous merger of three different massive galaxy
clusters.
It lies some 3.5 billion light-years away, toward the constellation Sculptor.
Dominated by dark matter,
the mega-cluster warps and distorts
the fabric of spacetime,
gravitationally lensing
even more distant objects.
Redder than the Pandora cluster galaxies
many of the lensed sources are very distant galaxies in the early
Universe, their lensed images stretched and distorted into arcs.
Of course distinctive
diffraction spikes mark foreground Milky Way
stars.
At the Pandora Cluster's estimated
distance this cosmic box spans about 6 million light-years.
But don't panic.
You can explore the tantalizing region in a
2 minute video tour.
APOD: 2023 May 19 - Curly Spiral Galaxy M63
Explanation:
A bright spiral galaxy of the northern sky,
Messier 63
is nearby,
about 30 million light-years distant toward the loyal constellation
Canes Venatici.
Also cataloged as NGC 5055, the majestic
island universe
is nearly 100,000 light-years across, about the size
of our own Milky Way.
Its bright core
and majestic
spiral arms lend the galaxy
its popular name, The Sunflower Galaxy.
This exceptionally deep exposure also follows
faint, arcing star streams far into the galaxy's
halo.
Extending nearly 180,000 light-years from the galactic center,
the star streams are likely remnants of
tidally disrupted
satellites of M63.
Other satellite galaxies of M63 can be spotted in
the remarkable wide-field image,
including faint
dwarf galaxies,
which could contribute to M63's star streams in the next few billion
years.
APOD: 2023 May 15 – M16: Eagle Nebula Deep Field
Explanation:
From afar, the whole thing looks like an
eagle.
A closer look at the
Eagle Nebula,
however, shows the
bright
region is actually a window into the center of a larger dark shell of
dust.
Through this window, a brightly-lit
workshop appears
where a whole open cluster
of stars is being formed.
In this cavity,
tall
pillars and
round globules of dark dust and cold
molecular gas
remain where stars are still forming.
Already visible are several young
bright blue stars
whose light and winds are burning away and pushing back the
remaining filaments
and walls of gas and dust.
The Eagle emission nebula,
tagged M16, lies about 6500
light years away, spans about 20 light-years,
and is visible with
binoculars
toward
the constellation of the Serpent
(Serpens).
This picture
involved
long and deep exposures and combined
three specific emitted colors emitted by
sulfur (colored as yellow),
hydrogen (red), and
oxygen (blue).
APOD: 2023 April 7 - Rigel Wide
Explanation:
Brilliant, blue, supergiant star Rigel
marks the foot of Orion the Hunter in
planet Earth's night.
Designated Beta Orionis,
it's at the center of this remarkably
deep and wide field of view.
Rigel's blue color indicates that it is much hotter than its
rival supergiant in Orion the yellowish
Betelgeuse (Alpha Orionis),
though both stars are massive enough to eventually
end their days
as
core collapse supernovae.
Some 860 light-years away, Rigel is hotter than the Sun too
and extends to about 74 times the solar radius.
That's about the size of the orbit of Mercury.
In the 10 degree wide frame toward the nebula rich
constellation, the Orion Nebula is at the upper left.
To the right of Rigel and illuminated by its brilliant blue starlight
lies the dusty Witch Head Nebula.
Rigel is part
of a multiple star system, though its companion stars
are much fainter.
APOD: 2023 April 1 - NGC 2442: Galaxy in Volans
Explanation:
Distorted galaxy NGC 2442
can be found in the southern constellation of the
flying fish,
(Piscis)
Volans.
Located about 50 million light-years away, the galaxy's two
spiral arms
extending from a pronounced central bar give it a
hook-shaped appearance in this deep colorful image,
with spiky foreground stars scattered across the telescopic field of
view.
The image also reveals the distant galaxy's
obscuring dust lanes, young blue star clusters and
reddish star forming regions
surrounding a core of yellowish light from an older population of stars.
But the star forming regions seem more concentrated along
the drawn-out (upper right)
spiral
arm.
The distorted structure is likely the result of an ancient
close encounter
with the smaller galaxy seen near the top left of the frame.
The two interacting galaxies are separated by about
150,000 light-years at the estimated distance of NGC 2442.
APOD: 2023 March 24 - Outbound Comet ZTF
Explanation:
Former darling
of the northern sky Comet C/2022E3 (ZTF) has
faded.
During its closest approach to our fair planet in
early February
Comet ZTF was a mere 2.3 light-minutes distant.
Then known as the green comet,
this visitor from the
remote Oort Cloud
is now nearly 13.3 light-minutes away.
In this deep image, composed of exposures
captured on March 21,
the comet still sports a broad, whitish dust tail and
greenish tinted coma though.
Not far on the sky
from Orion's bright star Rigel,
Comet ZTF shares the field of view
with faint, dusty nebulae and distant background galaxies.
The telephoto frame is
crowded with Milky Way stars toward the constellation Eridanus.
The influence of Jupiter's gravity on the comet's orbit as ZTF
headed for the inner solar system, may have
set the comet on an outbound journey,
never to return.
APOD: 2023 March 7 – Deep Field: The Large Magellanic Cloud
Explanation:
Is this a
spiral galaxy?
No. Actually, it is the
Large Magellanic Cloud (LMC), the largest
satellite galaxy of our own
Milky Way Galaxy.
The LMC is
classified
as a dwarf
irregular galaxy because of its normally
chaotic appearance.
In this deep and wide exposure, however, the full extent of the
LMC becomes visible.
Surprisingly, during longer exposures, the
LMC begins to resemble a
barred spiral galaxy.
The
Large Magellanic Cloud lies only about 180,000
light-years
distant towards the constellation of the
Dolphinfish
(Dorado).
Spanning about 15,000 light-years, the LMC was the site of SN1987A, the brightest and closest
supernova
in modern times.
Together with the
Small Magellanic Cloud (SMC), the LMC can
be seen in
Earth's southern hemisphere with the unaided eye.
APOD: 2023 March 3 - RCW 86: Historical Supernova Remnant
Explanation:
In 185 AD,
Chinese astronomers
recorded the appearance of a new star in the Nanmen asterism.
That part of the sky is
identified with Alpha and Beta Centauri on modern star charts.
The new star was visible to the naked-eye for months,
and is now thought to be the earliest
recorded supernova.
This deep telescopic view
reveals the wispy outlines of emission nebula RCW 86, just visible against
the starry background,
understood to be the remnant
of that stellar explosion.
Captured by the wide-field
Dark Energy Camera operating at Cerro
Tololo Inter-American Observatory in Chile,
the image traces the full extent of a ragged shell of gas ionized by the still
expanding shock wave.
Space-based images
indicate an abundance of the element iron in RCW 86 and
the absence of a neutron star or pulsar
within the remnant,
suggesting that the original supernova was Type Ia.
Unlike the core collapse
supernova explosion of a massive star, a
Type Ia supernova
is a thermonuclear
detonation on a white dwarf
star that accretes material from a companion in a binary star system.
Near the plane of our
Milky Way
galaxy and larger than the full moon on the sky this supernova remnant
is too faint to be seen by eye though.
RCW 86 is some 8,000 light-years distant and around 100 light-years across.
APOD: 2023 February 24 - Jones Emberson 1
Explanation:
Planetary nebula
Jones-Emberson 1
is the
death shroud
of a dying Sun-like star.
It lies some 1,600 light-years from Earth toward the
sharp-eyed
constellation Lynx.
About 4 light-years across,
the expanding remnant of the dying star's atmosphere was
shrugged off
into interstellar space, as the star's
central supply of hydrogen and then helium for fusion was
finally depleted after billions of years.
Visible near the center of the planetary nebula
is what remains of the stellar core, a blue-hot
white dwarf star.
Also known as PK 164 +31.1, the nebula is faint and very
difficult to glimpse at a telescope's eyepiece.
But this deep broadband image
combining 22 hours of exposure time does show it off in exceptional detail.
Stars within our own Milky Way galaxy as well as background galaxies
across the universe are scattered through the clear field of view.
Ephemeral
on the cosmic stage, Jones-Emberson 1
will fade away over the next few thousand years.
Its hot, central white dwarf star will take
billions
of years to cool.
APOD: 2022 October 24 - Clouds Around Galaxy Andromeda
Explanation:
What are those red clouds surrounding the Andromeda galaxy?
This galaxy, M31, is often imaged by planet Earth-based astronomers.
As the nearest large spiral galaxy, it is a familiar sight
with dark dust lanes, bright yellowish core, and
spiral arms traced
by clouds of bright blue stars.
A mosaic of well-exposed broad and narrow-band image data,
this deep portrait of our
neighboring island universe offers
strikingly unfamiliar features though,
faint reddish clouds of glowing
ionized hydrogen gas in the same wide field of view.
Most of the ionized hydrogen clouds surely
lie in the foreground of the scene, well within our
Milky Way Galaxy.
They are likely associated with the pervasive, dusty
interstellar cirrus
clouds scattered hundreds of
light-years above our own
galactic plane.
Some of the clouds, however, occur right in the
Andromeda galaxy itself, and some in
M110,
the small galaxy just below.
APOD: 2022 October 22 - NGC 1499: The California Nebula
Explanation:
Drifting through the Orion Arm of the spiral Milky Way Galaxy,
this cosmic cloud
by chance echoes the outline of California on the west coast of the
United States.
Our own Sun also lies within the Milky Way's
Orion Arm,
only about 1,500 light-years from the
California
Nebula.
Also known as
NGC 1499,
the classic emission nebula is around 100 light-years long.
The California Nebula shines with the telltale reddish glow
characteristic of
hydrogen atoms recombining with long lost
electrons.
The electrons have been stripped away,
ionized by energetic starlight.
Most likely providing the
energetic starlight
that ionizes much of the nebular gas is the bright, hot star
Xi Persei
just to the right of the nebula.
A popular target for astrophotographers, this deep image
reveals the
glowing nebula, obscuring dust,
and stars
across a 3 degree wide field of view.
The California nebula lies toward the constellation
Perseus,
not far from the Pleiades.
APOD: 2022 October 8 - Two Comets in Southern Skies
Explanation:
Heading for its closest approach to the Sun
or perihelion on December 20, comet
C/2017 K2 (PanSTARRS) remains a sight
for telescopic observers as it sweeps
through planet Earth's southern hemisphere skies.
First time visitor
from the
remote Oort cloud
this comet PanSTARRS sports
a greenish coma and whitish dust tail about half a
degree long at the upper left in a deep image from September 21.
It also shares the starry field of view toward the constellation
Scorpius with another comet,
73P/Schwassmann-Wachmann 3,
seen about 1 degree
below and right
of PanSTARRS.
Astronomers estimate that first time visitor comet
C/2017 K2 (PanSTARRS)
has been inbound from the Oort cloud for some 3 million years
along a hyperbolic orbit.
Schwassmann-Wachmann 3 is more familiar though.
The periodic comet loops through its own
elliptical orbit, from just beyond the orbit of Jupiter to the vicinity
of Earth's orbit, once every 5.4 years.
Just passing in the night, this comet PanSTARRS is about 20
light-minutes from Earth in the
September 21 image.
Seen to be disintegrating since 1995,
Schwassmann-Wachmann 3
was about 7.8 light-minutes away.
APOD: 2022 August 20 - Stardust and Comet Tails
Explanation:
Heading for its closest approach to the Sun, or perihelion,
on December 19 comet
C/2017 K2 (PanSTARRS) remains a sight
for telescopic observers as it sweeps through planet Earth's skies
in the constellation Scorpius.
The comet currently
sports a greenish
coma, long whitish dust tail, and short ion tail in this
deep image from August 18.
The 2x3 degree wide field of view includes part of the dusty
nebula IC 4592 reflecting blue starlight.
Also known as the Blue Horsehead Nebula,
IC 4592 is about 400 light-years distant while the comet is just under
17 light-minutes away.
First spotted at a distance well beyond the orbit of Saturn
C/2017 K2
is on its maiden voyage to the inner solar system,
a pristine visitor from the
remote Oort cloud.
APOD: 2022 August 7 - Meteor before Galaxy
Explanation:
What's that green streak in front of the Andromeda galaxy?
A meteor.
While photographing the
Andromeda galaxy in 2016,
near the peak of the
Perseid
Meteor
Shower,
a small pebble from deep space
crossed right in front of our
Milky Way Galaxy's far-distant companion.
The small
meteor
took only a fraction of a second to pass through this 10-degree field.
The meteor flared
several times while braking violently upon entering
Earth's atmosphere.
The green color
was created, at least in part, by the meteor's gas glowing as it vaporized.
Although the exposure was timed to catch a
Perseid meteor,
the orientation of the imaged streak seems a better match to a meteor from the
Southern Delta Aquariids, a
meteor shower that peaked a few weeks earlier.
Not coincidentally, the
Perseid Meteor Shower peaks
later this week, although
this year
the meteors will have to outshine a
sky brightened by a nearly full moon.
APOD: 2022 July 13 - Webb's First Deep Field
Explanation:
This is the deepest,
sharpest infrared image of the cosmos so far.
The view
of the
early Universe
toward the southern constellation Volans
was achieved in 12.5 hours of exposure with the NIRCam instrument on the
James Webb Space Telescope.
Of course the stars with six visible spikes are well within our own
Milky Way.
Their diffraction
pattern is characteristic of Webb's 18 hexagonal mirror
segments operating together as a single 6.5 meter diameter primary
mirror.
The thousands of galaxies flooding the field of view are members of the
distant galaxy cluster SMACS0723-73, some 4.6 billion light-years away.
Luminous arcs that seem to infest the deep field are
even more distant galaxies though.
Their images are distorted and magnified by the
dark matter dominated mass of the galaxy cluster, an effect
known as gravitational lensing.
Analyzing light
from two separate arcs below the bright spiky star,
Webb's NIRISS instrument indicates the arcs
are both images of the same background galaxy.
And that galaxy's light took about 9.5 billion years to reach the
James Webb Space Telescope.
APOD: 2022 June 9 - Cosmic Clouds in Cygnus
Explanation:
These cosmic clouds of gas and dust drift
through rich star fields along the
plane of our Milky Way Galaxy toward the high flying constellation
Cygnus.
They're too faint to be seen with the unaided eye though, even on a
clear, dark night.
Image data from a
camera and telephoto lens
using narrowband filters
was used to construct this 10 degree wide field of view.
The deep mosaic reveals a region that includes
star forming dust clouds seen in silhouette against the
characteristic glow of atomic hydrogen and oxygen gas.
NGC 6888 is the standout emission nebula near the top.
Blown by winds from a massive Wolf-Rayet star it's
about 25 light-years across and known as the
Crescent Nebula.
A faint bluish curl just below center in the frame is also the
signature of a Wolf-Rayet star.
Burning fuel at a prodigious rate and near the end of their stellar
lives, both stars will ultimately go out with a bang in a spectacular
supernova explosion.
Toward the right, a massive, young O type star powers the glow of Sh2-101, the
Tulip Nebula.
APOD: 2022 May 24 - A Deep Sky Behind an Eclipsed Moon
Explanation:
The plan was to capture a picturesque part of the sky that was hosting an unusual guest.
The result included a bonus — an additional and unexpected guest.
The beautiful background features part of the central band of our
Milky Way galaxy on the far left, and the
colorful clouds of
Rho Ophiuchi in the image center.
The unusual guest, a dimmed and
reddened Moon on the right, was expected because the image was taken during last week’s
total lunar eclipse.
The timing had to be right because
the Moon — both before and after eclipse —
would be so bright it would overwhelm the background.
The unexpected guest was the bright meteor across the image center.
The fleeting meteor streak was
captured
on only one of the 10 consecutively-captured deep-field images from
La Palma in the
Spanish
Canary Islands,
while the
eclipsed Moon image was taken
immediately afterwards with the same camera and from the same location.
The next total lunar eclipse — also quite expected —
will occur in early November.
APOD: 2022 May 10 - NGC 6334: The Cats Paw Nebula
Explanation:
Nebulas are perhaps as famous for being identified with familiar shapes as perhaps
cats
are for getting into
trouble.
Still, no known cat could have created the vast
Cat's Paw Nebula
visible toward
the constellation of the Scorpion
(Scorpius.
At 5,500
light years
distant, Cat's
Paw is an
emission nebula with a red color that originates from an abundance of
ionized
hydrogen atoms.
Alternatively known as the
Bear Claw Nebula and cataloged as
NGC 6334,
stars nearly ten times the mass of our
Sun have been born
there in only the past few million years.
Pictured here is
a deep field image of the
Cat's Paw
Nebula in light emitted by
hydrogen, oxygen, and sulfur.
APOD: 2022 April 7 - Messier 24: Sagittarius Star Cloud
Explanation:
Unlike most entries
in Charles Messier's famous catalog of deep sky objects,
M24
is not a bright galaxy, star cluster, or nebula.
It's a gap in nearby, obscuring interstellar dust clouds that allows
a view of the distant stars in the Sagittarius spiral arm
of our Milky Way galaxy.
When you gaze at the star cloud
with binoculars or small telescope you are
looking through a window over 300 light-years wide at stars some
10,000 light-years or more from Earth.
Sometimes called the Small Sagittarius Star Cloud, M24's luminous
stars fill
this gorgeous starscape.
Covering over 3 degrees or the width of 6 full moons in the
constellation Sagittarius,
the telescopic field of view includes
dark markings
B92 and B93 just above center, along with other
clouds of dust and glowing nebulae toward the center of the Milky Way.
APOD: 2022 April 5 - Seven Sisters versus California
Explanation:
On the upper right, dressed in blue, is the
Pleiades.
Also known as the
Seven Sisters and
M45,
the Pleiades
is one of the brightest and
most easily visible
open clusters
on the sky.
The Pleiades
contains over 3,000 stars, is about 400 light years away, and only 13 light
years across.
Surrounding the stars is a spectacular blue
reflection nebula
made of fine
dust.
A
common legend is that one of the brighter stars
faded since the cluster was named.
On the lower left, shining in red, is the
California Nebula.
Named for its shape, the
California
Nebula is much dimmer and hence harder to see
than the Pleiades.
Also known as NGC 1499, this mass of red glowing
hydrogen gas is about 1,500 light years away.
Although about 25 full moons could fit
between them, the
featured wide angle, deep field image composite has captured
them
both.
A careful inspection
of the deep image will also reveal the star forming region
IC 348 and
the molecular cloud
LBN 777 (the Baby Eagle Nebula).
APOD: 2022 February 23 - Orion over Green Bank
Explanation:
What will the huge Green Bank Telescope discover tonight?
Pictured, the
Robert C. Byrd Green Bank Telescope (GBT)
on the lower right is the largest fully-pointable single-dish
radio telescope in the world.
With a central dish larger than a football field, the
GBT
is nestled in the hills of
West Virginia,
USA in a
radio quiet zone where the use of cell phones, WiFi emitters,
and even microwave ovens are limited.
The GBT explores our universe
not only during the night -- but during the day, too,
since the daytime sky is typically dark in
radio waves.
Taken in late January, the featured image was planned for months to get the setting
location of Orion just right.
The image is a composite of a foreground shot taken over
a kilometer away from the
GBT,
and a background shot built up of long exposures during the previous night.
The deep background image of
Orion
is fitting
because the GBT is famous for, among
many discoveries,
mapping the
unusual magnetic field in the
Orion Molecular Cloud Complex.
APOD: 2022 January 11 - Orions Belt Region in Gas and Dust
Explanation:
You may have seen Orion's belt before -- but not like this.
The three bright stars across this image are, from left to right,
Mintaka,
Alnilam, and
Alnitak: the iconic
belt stars of
Orion.
The rest of the
stars in the frame have been digitally removed to
highlight the surrounding clouds of glowing gas and dark dust.
Some of these clouds have intriguing shapes, including the
Horsehead and
Flame Nebulas, both near Alnitak on the lower right.
This deep image,
taken last month from the
Marathon Skypark
and Observatory in
Marathon,
Texas,
USA,
spans about 5 degrees, required about 20 hours of exposure,
and was processed to reveal the gas and dust that we would
really see if we were much closer.
The famous Orion Nebula
is off to the upper right of this colorful field.
The entire region lies only about 1,500
light-years
distant and so is one of the closest and
best studied star formation nurseries known.
APOD: 2021 August 2 - The Hubble Ultra Deep Field in Light and Sound
Explanation:
Have you heard about the Hubble Ultra-Deep Field?
Either way, you've likely not
heard about it like this --
please run your cursor over the featured image and listen!
The Hubble Ultra-Deep Field (HUDF) was created in 2003-2004 with the
Hubble Space Telescope staring for a
long time toward near-empty space so that distant,
faint galaxies would become visible.
One of the most famous images in astronomy, the
HUDF is featured here in a vibrant way --
with sonified distances.
Pointing to a galaxy will play a
note that indicates its approximate redshift.
Because
redshifts
shift light toward the red end of the
spectrum of light,
they are depicted here by a shift of tone toward the low end of the
spectrum of sound.
The further the galaxy, the greater its
cosmological redshift
(even if it appears blue), and the lower the tone that will be played.
The average galaxy in the HUDF
is about 10.6 billion
light years away and sounds like an
F#.
What's the
most distant galaxy you can find?
APOD: 2021 May 22 - Markarian's Chain
Explanation:
Near the heart of the
Virgo Galaxy Cluster
the string of galaxies known as
Markarian's
Chain stretches across this deep
telescopic field of view.
Anchored in the frame at bottom center by prominent lenticular galaxies,
M84 (bottom)
and M86,
you can follow the chain up and to the right.
Near center you'll spot the pair of interacting galaxies
NGC 4438 and NGC 4435, known to some as
Markarian's Eyes.
Its center an estimated 50 million light-years distant,
the Virgo Cluster itself is the nearest
galaxy cluster.
With up to about 2,000 member galaxies, it has a
noticeable gravitational influence on our own
Local Group of Galaxies.
Within the Virgo Cluster at least seven galaxies in Markarian's Chain
appear to move
coherently,
although others may appear to be part of the chain by chance.
APOD: 2021 March 18 - Stardust in the Perseus Molecular Cloud
Explanation:
Clouds of stardust drift through this deep skyscape,
across the
Perseus molecular cloud
some 850 light-years away.
Dusty nebulae reflecting light from embedded young stars
stand out in the nearly 2 degree wide telescopic field of view.
With a characteristic bluish color
reflection nebula NGC 1333 is at
center,
vdB 13 at top right,
with rare yellowish reflection nebula
vdB 12 near the top of the frame.
Stars are forming
in the molecular cloud, though most
are obscured at visible wavelengths by the pervasive dust.
Still, hints of contrasting red emission from Herbig-Haro objects,
the jets and shocked glowing gas emanating from recently formed stars,
are evident
in NGC 1333.
The chaotic environment may be similar to one in which our own Sun
formed over 4.5 billion years ago.
At the estimated distance of the Perseus molecular cloud,
this cosmic scene would span about 40 light-years.
APOD: 2020 December 4 - Curly Spiral Galaxy M63
Explanation:
A bright spiral galaxy of the northern sky,
Messier 63
is nearby,
about 30 million light-years distant toward the loyal constellation
Canes Venatici.
Also cataloged as NGC 5055, the majestic
island universe
is nearly 100,000 light-years across, about the size
of our own Milky Way.
Its bright core
and majestic
spiral arms lend the galaxy
its popular name, The Sunflower Galaxy,
while this exceptionally deep exposure also follows
faint, arcing star streams far into the galaxy's
halo.
Extending nearly 180,000 light-years from the galactic center
the star streams are likely remnants of
tidally disrupted
satellites of M63.
Other satellite galaxies of M63 can be spotted in this
remarkable wide-field image,
made with a small telescope, including five
newly
identified
faint dwarf galaxies,
which could contribute to M63's star streams in the next few billion
years.
APOD: 2020 November 12 - Comet ATLAS and Orion's Belt
Explanation:
With its closest approach to planet Earth scheduled for November 14,
this Comet ATLAS (C/2020 M3) was discovered just this summer,
another comet found by the NASA funded
Asteroid Terrestrial-impact Last Alert System.
It won't get as bright
as Comet NEOWISE
but it can still be spotted using binoculars, as it
currently sweeps through the familiar constellation of Orion.
This telephoto field from November 8,
blends exposures registered on the comet with exposures
registered on Orion's stars.
It creates an effectively deep skyview that shows colors and details you
can't quite see though, even in binoculars.
The comet's telltale greenish coma is toward the upper left, above
Orion's three belt stars lined-up across the frame below center.
You'll also probably spot the Orion Nebula, and famous Horsehead Nebula
in the stunning field of view.
Of course one of
Orion's belt stars is nearly 2,000 light-years away.
On November 14,
this comet ATLAS
will fly a mere 2.9 light-minutes from Earth.
APOD: 2020 November 10 - The Central Soul Nebula Without Stars
Explanation:
This cosmic close-up looks deep inside the
Soul Nebula.
The dark and brooding
dust clouds near the top,
outlined by bright
ridges of glowing gas, are cataloged as
IC 1871.
About 25 light-years
across, the telescopic field of view spans only
a small part of the much larger
Heart and Soul nebulae.
At an estimated distance of 6,500
light-years
the star-forming complex lies within the
Perseus spiral arm of our
Milky Way Galaxy, seen in planet
Earth's skies toward the constellation Cassiopeia.
An example of
triggered star formation,
the dense star-forming clouds in the
Soul Nebula are themselves
sculpted by the intense winds and radiation of the region's
massive young stars.
In the
featured image,
stars have been digitally removed to highlight
the commotion in the gas and dust.
APOD: 2020 October 10 - Virgo Cluster Galaxies
Explanation:
Galaxies of the Virgo Cluster
are scattered across this deep telescopic field of view.
The cosmic scene spans about three Full Moons, captured in dark skies near
Jalisco, Mexico, planet Earth.
About 50 million light-years distant, the Virgo Cluster is the
closest large galaxy cluster to our own local galaxy group.
Prominent here are Virgo's bright elliptical galaxies from the
Messier catalog,
M87 at the top left, and M84 and M86 seen
(bottom to top) below and right of center.
M84 and M86 are recognized as part of
Markarian's Chain,
a visually striking line-up of galaxies vertically on the
right side of this frame.
Near the middle of the chain lies an intriguing interacting pair of galaxies,
NGC 4438 and NGC 4435,
known to some as Markarian's Eyes.
Of course
giant elliptical galaxy M87
dominates the Virgo cluster.
It's the home of a super massive black hole,
the first black hole ever imaged by planet Earth's
Event Horizon Telescope.
APOD: 2020 August 29 - Martian Chiaroscuro
Explanation:
Deep shadows
create dramatic contrasts between light and dark in
this
high-resolution close-up of the martian surface.
Recorded on January 24, 2014 by the HiRISE camera on board the
Mars Reconnaissance Orbiter,
the scene spans about 1.5 kilometers.
From 250 kilometers above the Red Planet the camera is looking
down at a sand dune field in a southern highlands crater.
Captured when the Sun was about 5 degrees above the local horizon,
only the dune crests were caught in full sunlight.
A long, cold winter was coming to the
southern hemisphere and bright ridges of
seasonal frost line the martian dunes.
The Mars Reconnaissance Orbiter,
one of the oldest
operating spacecraft at the Red Planet,
celebrated the 15th anniversary of its launch from planet Earth
on August 12.
APOD: 2020 August 27 - Shell Galaxies in Pisces
Explanation:
This intergalactic skyscape features a peculiar system
of galaxies cataloged as Arp 227 some 100 million light-years
distant.
Swimming within the boundaries of the
constellation Pisces,
Arp 227 consists of the two galaxies
prominent right of center,
the curious shell galaxy NGC 474 and its blue,
spiral-armed neighbor NGC 470.
The faint, wide arcs or
shells
of NGC 474 could have been formed by a
gravitational encounter with neighbor NGC 470.
Alternately the shells could be
caused by a merger with a
smaller galaxy producing an effect analogous to ripples across
the surface of a pond.
The large galaxy on the top lefthand side of the deep image,
NGC 467, appears to be surrounded by faint shells too,
evidence of another
interacting galaxy system.
Intriguing background galaxies are scattered around
the field that also includes spiky foreground stars.
Of course, those stars lie well within our own
Milky Way Galaxy.
The field of view spans 25 arc minutes or about 1/2 degree
on the sky.
APOD: 2020 August 7 - The Pipe Nebula
Explanation:
East of Antares,
dark markings sprawl through crowded
star fields toward the center of our Milky Way Galaxy.
Cataloged in the early 20th
century by astronomer
E. E. Barnard,
the obscuring interstellar dust clouds
include B59, B72, B77 and B78,
seen in against the starry background.
Here, their combined shape suggests
a pipe
stem and bowl,
and so the dark nebula's popular name is the Pipe Nebula.
The deep and expansive view
covers a full 10 by 10 degree field in the
pronounceable
constellation Ophiuchus.
The Pipe Nebula is part of the Ophiuchus dark cloud complex
located at a distance of about 450 light-years.
Dense cores
of gas and dust within the Pipe Nebula are collapsing to form stars.
APOD: 2020 July 26 – A Flight through the Hubble Ultra Deep Field
Explanation:
What would it look like to fly through the distant universe?
To find out, a team of astronomers estimated the relative distances
to over 5,000 galaxies in one of the most distant fields of galaxies ever imaged: the
Hubble Ultra Deep Field
(HUDF).
Because it takes light a long time to cross the universe, most galaxies visible in the
featured video
are seen when the universe was only a fraction of its current age, were
still forming, and have unusual shapes when compared to modern galaxies.
No mature looking spiral galaxies such as our
Milky Way or the
Andromeda galaxy yet exist.
Toward the end of the video the
virtual observer flies past the
farthest galaxies
in the HUDF field, recorded to have a
redshift past 8.
This early class of low luminosity
galaxies likely contained
energetic stars emitting light that
transformed much of the
remaining normal matter
in the universe from a cold gas to a hot ionized
plasma.
APOD: 2020 June 6 - Comet PanSTARRs and the Galaxies
Explanation:
Comet PanSTARRs, C/2017 T2,
shared this stunning telescopic field of
view with galaxies
M81 and M82 on May 22/23.
Of course, the galaxies were some 12 million light-years distant and
the comet about 14 light-minutes away, seen in
planet Earth's sky toward the Big Dipper.
A new visitor
from the Oort Cloud, this
Comet PanSTARRs
was discovered in 2017 by the PanSTARRs survey telescope when
the comet was over 1 light-hour from the Sun, almost as distant
as the orbit of Saturn.
With a beautiful
coma and dust tail,
this comet has been a
solid northern hemisphere performer for telescope wielding
comet watchers this May, following its closest approach to the Sun
on May 4.
In this deep image
from dark California skies the outbound comet even seems to
develop a short anti-tail as it leaves
the inner Solar System.
APOD: 2020 February 3 - Solar Granules at Record High Resolution
Explanation:
Why does the Sun's surface keep changing?
The help find out, the US
National Science Foundation
(NSF) has
built the
Daniel K. Inouye Solar Telescope in
Hawaii,
USA.
The Inouye telescope has a larger mirror that enables the capturing of images of higher resolution, at a faster rate, and in more colors than ever
before.
Featured are recently-released
first-light images taken over 10 minutes and combined into a 5-second time-lapse video.
The video captures an area on the Sun roughly the size of our Earth, features
granules roughly the size of a country, and resolves features as small as 30-kilometers across.
Granule centers are bright due to the upwelling hot
solar
plasma,
while granule edges are dim due to the cooled plasma falling back.
Some regions between granules edges are
very bright as they are
curious magnetic windows into a deep and hotter solar interior.
How the Sun's magnetic field
keeps changing, channeling energy, and affecting the distant Earth, among
many other topics, will be studied for years to come using data from the new
Inouye telescope.
APOD: 2020 January 22 - The Hyades Star Cluster
Explanation:
It is the closest cluster of stars to the Sun.
The Hyades
open cluster
is bright enough to have been remarked on even thousands of years ago,
yet is not as bright or compact as the
nearby Pleiades (M45) star cluster.
Pictured here is a particularly deep image of
the Hyades which has brings out vivid
star colors and faint coincidental nebulas.
The brightest star in the field is yellow
Aldebaran,
the eye of the bull toward the
constellation of Taurus.
Aldebaran, at 65
light-years away, is now known to be unrelated to the
Hyades cluster,
which lies about 150 light-years away.
The central
Hyades stars
are spread out over about 15 light-years.
Formed about 625 million years ago,
the Hyades likely shares a common origin with the
Beehive cluster (M44), a naked-eye open star cluster toward the
constellation of Cancer, based on
M44's motion
through space and remarkably similar age.
APOD: 2019 August 23 - NGC 1499: The California Nebula
Explanation:
Drifting through the Orion Arm of the spiral Milky Way Galaxy,
this
cosmic cloud
by chance echoes the outline of California on the west coast of the
United States.
Our own Sun also lies within the Milky Way's
Orion
Arm, only about 1,500 light-years from the
California
Nebula.
Also known as NGC 1499,
the classic emission nebula is around 100
light-years long.
The California Nebula shines with the telltale reddish glow
characteristic of
hydrogen atoms recombining with long lost
electrons.
The electrons have been stripped away,
ionized by energetic starlight.
Most likely providing the
energetic
starlight that ionizes
much of the nebular gas is the bright, hot, bluish star
Xi Persei
just to the right of the nebula.
A popular target for astrophotographers, this deep
California Nebula image
is a 6 panel telecopic mosaic and covers a
wide field of view.
The nebula lies toward the constellation
Perseus,
not far from the Pleiades.
APOD: 2019 August 21 - The Orion You Can Almost See
Explanation:
Do you recognize this constellation?
Although it is one of the
most recognizable star groupings on the sky,
this is a
more full Orion than you can see --
an Orion only revealed with long exposure digital
camera imaging and
post-processing.
Here the cool
red giant
Betelgeuse
takes on a strong orange tint as the brightest star at the lower left.
Orion's hot blue stars are numerous, with
supergiant
Rigel balancing Betelgeuse on the upper right, and
Bellatrix at the upper left.
Lined up in
Orion's belt are three stars
all about 1,500
light-years away, born from the constellation's well-studied
interstellar clouds.
To the right of Orion's belt is a bright but fuzzy patch that might also
look familiar -- the stellar nursery known as
Orion's Nebula.
Finally, just barely visible to the
unaided eye but quite striking here is
Barnard's Loop -- a huge gaseous emission nebula surrounding Orion's Belt and Nebula discovered over 100 years ago by the pioneering Orion photographer
E. E. Barnard.
APOD: 2019 May 31 - Lynds Dark Nebula 1251
Explanation:
Stars are forming in Lynds Dark Nebula
(LDN)
1251.
About 1,000 light-years away and drifting above the plane of our Milky
Way galaxy, the dusty molecular cloud
is part of a complex of dark nebulae mapped toward the
Cepheus flare region.
Across the spectrum,
astronomical explorations of the obscuring
interstellar clouds reveal energetic shocks and outflows
associated with newborn stars, including the telltale reddish glow from
scattered
Herbig-Haro objects seen in this sharp
image.
Distant background galaxies also lurk on the scene,
visually buried behind the dusty expanse.
The deep telescopic field of view imaged with broadband filters
spans about two full moons on the sky, or 17 light-years at the
estimated distance of LDN 1251.
APOD: 2019 May 21 - Deep Field: Nebulae of Sagittarius
Explanation:
These three bright nebulae are often featured on telescopic tours of the
constellation Sagittarius and the crowded starfields of
the central Milky Way.
In fact, 18th century cosmic tourist
Charles
Messier cataloged two of them;
M8, the large nebula just left of center,
and colorful M20 on the top left.
The third emission region includes
NGC 6559
and can be found to the right of M8.
All three are
stellar nurseries about
five thousand light-years or so distant.
Over a hundred
light-years across, the expansive M8
is also known as the
Lagoon Nebula.
M20's popular moniker is the
Trifid.
Glowing hydrogen gas creates the dominant red color of the
emission nebulae.
In striking contrast, blue hues in the
Trifid are due to dust reflected starlight.
Recently formed bright blue stars are visible nearby.
The colorful composite skyscape was recorded in 2018 in
Teide National Park in the
Canary Islands,
Spain.
APOD: 2018 November 28 - IC 1871: Inside the Soul Nebula
Explanation:
This cosmic close-up looks deep inside the
Soul Nebula.
The dark and brooding
dust clouds on the left, outlined by bright
ridges of glowing gas, are cataloged as IC 1871.
About 25 light-years across,
the telescopic field of view spans only
a small part of the much larger
Heart and Soul nebulae.
At an estimated distance of 6,500 light-years the star-forming
complex lies within the
Perseus spiral arm of our
Milky Way Galaxy, seen in planet
Earth's skies toward the constellation Cassiopeia.
An example of
triggered star formation,
the dense star-forming clouds of IC 1871 are themselves
sculpted by the intense winds and radiation of the region's
massive young stars.
The
featured image
appears mostly red due to the emission of a
specific color of light emitted by
excited hydrogen gas.
APOD: 2018 October 31 - R Leporis: A Vampire's Star
Explanation:
Better known as
Hind's Crimson
Star, R Leporis is a rare star in planet Earth's night sky.
It's also a shocking shade of red.
The star's discoverer,
19th century English astronomer
John Russell
Hind, reported that it appeared
in a telescope "... like a drop of blood on a black field."
Located
1,360 light-years away in the
constellation
Lepus the star is a Mira-type variable,
changing its brightness over a period of about 14 months.
R Leporis is now recognized as
a carbon star,
a very cool and highly evolved
red giant
with an extreme abundance of carbon.
Extra carbon in carbon stars is created by
helium
fusion near the dying stellar core and dredged up into the
stars' outer layers.
The dredge-up results in an overabundance of simple carbon molecules,
like CO, CH, CN, and C2.
While it's true
that cool stars radiate most of their energy in
red and infrared light, the carbon molecules
strongly absorb what little blue light is left and give
carbon stars an exceptionally deep red color.
R Leporis is losing its carbon-rich atmosphere into the surrounding
interstellar material through a strong stellar wind though,
and could be near the transition to a
planetary nebula.
Oh, and Happy Halloween from the folks at APOD.
APOD: 2018 September 19 - Cocoon Nebula Deep Field
Explanation:
Inside the Cocoon Nebula is a newly developing cluster of stars.
The cosmic Cocoon on the upper right also punctuates
a long trail of obscuring interstellar dust clouds to its left.
Cataloged as
IC 5146,
the beautiful nebula is nearly 15 light-years wide, located
some 3,300 light years away toward the northern constellation of the Swan
(Cygnus).
Like other star forming regions, it stands out
in red, glowing, hydrogen gas
excited by young, hot stars and blue, dust-reflected starlight
at the edge of a nearly invisible
molecular cloud.
In fact, the bright star near the center of this nebula is likely
only a few hundred thousand years old, powering the nebular glow as it
slowly clears out a cavity in the
molecular cloud's star forming dust and gas.
This
exceptionally deep color view
of the Cocoon Nebula traces
tantalizing features within and surrounding the dusty
stellar
nursery.
APOD: 2018 September 13 - Comet, Clusters, and Nebulae
Explanation:
Bright enough for binocular viewing
Comet 21P /
Giacobini-Zinner stands out, even in this
deep telephoto
mosaic of the star cluster
and nebula rich constellation Auriga
the Charioteer.
On the night of September 9 its greenish coma and diffuse tail contrast
with the colorful stars and reddish emission nebulae in the
almost 10 degree field of view along the Milky Way.
The comet was near its perihelion and closest approach to Earth,
about 200 light-seconds away.
Riding across the distant background just above the comet's tail
are well-known Auriga star clusters M38 (left of center) and
M36 (toward the right) about 4,000 light-years away.
At the top left, emission region IC 405 is only 1,500 light-years
distant, more dramatically known as the
Flaming Star Nebula.
To its right lies IC 410, 12,000 light-years away and
famous for its star-forming
cosmic tadpoles.
A child of
our
Solar System Giacobini-Zinner is a periodic
comet orbiting the Sun once every 6.5 years, and
the parent body of October's
Draconids meteor shower.
APOD: 2018 August 12 - Meteor before Galaxy
Explanation:
What's that green streak in front of the Andromeda galaxy?
A meteor.
While photographing the
Andromeda galaxy in 2016,
near the peak of the
Perseid
Meteor
Shower, a sand-sized rock from deep space
crossed right in front of our
Milky Way Galaxy's far-distant companion.
The small
meteor
took only a fraction of a second to pass through this 10-degree field.
The meteor flared
several times while braking violently upon entering
Earth's atmosphere.
The green color
was created, at least in part, by the meteor's gas glowing as it vaporized.
Although the exposure was timed to catch a
Perseids meteor,
the orientation of the imaged streak seems a better match to a meteor from the
Southern Delta Aquariids, a
meteor shower that peaked a few weeks earlier.
Not coincidentally, the
Perseid Meteor Shower peaks
again tonight.
APOD: 2018 July 2 - From the Galactic Plane through Antares
Explanation:
Behold one of the most photogenic regions of the night sky, captured impressively.
Featured, the band of our
Milky Way Galaxy runs diagonally along the far left, while the
colorful Rho Ophiuchus
region including the bright orange star
Antares is visible just right of center,
and the nebula
Sharpless 1
(Sh2-1) appears on the far right.
Visible in front of the
Milk Way band are several famous nebulas including the
Eagle Nebula (M16), the
Trifid Nebula (M20), and the
Lagoon Nebula (M8).
Other notable nebulas include the
Pipe and
Blue Horsehead.
In general,
red emanates from nebulas glowing in the light of exited
hydrogen gas, while blue marks
interstellar dust preferentially
reflecting the light of bright young stars.
Thick dust appears otherwise dark brown.
Large balls of stars visible include the globular clusters
M4,
M9,
M19,
M28, and
M80,
each marked on the
annotated companion image.
This extremely wide field -- about 50 degrees across -- spans the constellations of
Sagittarius is on the lower left,
Serpens on the upper left,
Ophiuchus
across the middle, and
Scorpius on the right.
It took over 100 hours of sky imaging, combined with
meticulous planning and digital processing, to create this image.
APOD: 2018 June 29 - Messier 24: Sagittarius Star Cloud
Explanation:
Unlike most entries
in Charles Messier's famous catalog of deep sky objects,
M24
is not a bright galaxy, star cluster, or nebula.
It's a gap in nearby, obscuring interstellar dust clouds that allows
a view of the distant stars in the Sagittarius spiral arm
of our Milky Way galaxy.
When you gaze at the star cloud
with binoculars or small telescope you are
looking through a window over 300 light-years wide at stars some
10,000 light-years or more from Earth.
Sometimes called the Small Sagittarius Star Cloud, M24's luminous
stars fill the left side of
this gorgeous starscape.
Covering about 4 degrees or the width of 8 full moons in the
constellation Sagittarius,
the telescopic field of view contains many
small, dense clouds of dust
and nebulae toward the center of the Milky Way,
including reddish emission from IC 1284
near the top of the frame.
APOD: 2018 June 28 - Sigma Octantis and Friends
Explanation:
South
pole star Sigma Octantis
(of the constellation Octans) is on the left of this starry expanse
spanning over 40 degrees across far southern skies.
You'll have to look hard
to find it,
though.
The southern hemisphere's faint counterpart to the north star Polaris,
Sigma Octantis is a little over one degree from the
South Celestial Pole.
Also known as Polaris Australis,
Sigma Octantis
is dimmer than 5th magnitude, some 25 times fainter than Polaris and
not easy to see with the unaided eye.
In fact,
it may be the faintest star depicted on a national flag.
The remarkable deep and wide-field view also covers faint,
dusty galactic cirrus clouds, bounded at the right
by the star clusters and nebulae along
southern reaches of the plane of our
Milky Way galaxy.
Near the upper right corner is yellowish Gamma Crucis, the top of the
Southern Cross.
Easy to pick out above and right of center is the long
Dark Doodad
nebula in the southern constellation Musca, the Fly.
APOD: 2018 June 5 - Complex Jupiter
Explanation:
How complex is Jupiter?
NASA's
Juno mission to Jupiter is finding the Jovian giant to be
more complicated than expected.
Jupiter's magnetic field has been
discovered to be much different from our Earth's simple dipole field, showing
several poles embedded in a complicated network more convoluted in the north than the south.
Further, Juno's radio measurements show that
Jupiter's atmosphere shows structure well below the upper cloud deck -- even hundreds of kilometers deep.
Jupiter's newfound complexity is evident also in southern clouds, as shown in the
featured image.
There, planet-circling
zones and belts that dominate near the equator decay into a
complex miasma of continent-sized storm swirls.
Juno continues in its looping elliptical orbit,
swooping near the huge planet
every 53 days and exploring a slightly different sector each time around.
APOD: 2018 April 14 - Martian Chiaroscuro
Explanation:
Deep shadows
create dramatic contrasts between light and dark in
this
high-resolution close-up of the martian surface.
Recorded on January 24, 2014 by the HiRISE camera onboard the
Mars Reconnaissance Orbiter, the scene
spans about 1.5 kilometers.
From 250 kilometers above the Red Planet the camera is looking
down at a sand dune field in a southern highlands crater.
Captured when the Sun was about 5 degrees above the local horizon,
only the dune crests were caught in full sunlight.
A long, cold winter is coming to the
southern hemisphere and bright ridges of
seasonal frost line the martian dunes.
APOD: 2018 March 30 - NGC 247 and Friends
Explanation:
About 70,000 light-years across,
NGC 247
is a spiral galaxy smaller than our Milky Way.
Measured to be
only 11 million light-years distant it is nearby though.
Tilted nearly edge-on as seen
from our perspective,
it dominates this telescopic field of view toward the
southern constellation Cetus.
The pronounced void on one side of the galaxy's disk recalls
for some its popular name, the Needle's Eye galaxy.
Many background galaxies are visible in
this sharp
galaxy portrait, including the remarkable string of four galaxies
just below and left of NGC 247 known
as Burbidge's Chain.
Burbidge's Chain galaxies are about 300 million light-years distant.
The deep image even reveals that the two leftmost galaxies in the chain are
apparently interacting, joined by a faint bridge of material.
NGC 247 itself is part of the Sculptor Group of galaxies along with the
shiny spiral NGC 253.
APOD: 2018 March 5 - The Hubble Ultra Deep Field in Light and Sound
Explanation:
Have you heard about the Hubble Ultra-Deep Field?
Either way, you've likely not
heard about it like this -- please run your pointer over the featured image and listen!
The Hubble Ultra-Deep Field (HUDF) was created in 2003-2004 with the
Hubble Space Telescope staring for a
long time toward near-empty space so that distant,
faint galaxies would become visible.
One of the most famous images in astronomy, the
HUDF is featured here in a vibrant way --
with sonified distances.
Pointing to a galaxy will play a
note that indicates its approximate redshift.
Because
redshifts
shift light toward the red end of the
spectrum of light,
they are depicted here by a shift of tone toward the low end of the
spectrum of sound.
The further the galaxy, the greater its
cosmological redshift (even if it appears blue), and the lower the tone that will be played.
The average galaxy in the
HUDF is about 10.6 billion
light years away and sounds like an
F#.
What's the most distant galaxy you can find?
This Astronomy Picture of the Day (APOD) is based on
an entry of new site called
Astronomy Sound of the Month (AstroSoM).
APOD: 2018 January 18 - Blue Comet in the Hyades
Explanation:
Stars of the Hyades
cluster are scattered through this mosaic
spanning over 5 degrees on the sky toward the constellation Taurus.
Presently cruising through the Solar System, the
remarkably blue comet
C/2016 R2 PanSTARRS is placed in
the wide field of view using image data from January 12.
With the apex of the V-shape in the Hyades cluster
positioned near the top center,
bright
Aldebaran, alpha star of Taurus,
anchors the frame at the lower right.
A cool red giant, Aldebaran is seen in orange hues in the
colorful starfield.
While the stars of the Hyades are gathered 151 light-years away,
Aldebaran lies only 65 light-years distant and so is separate
from the cluster stars.
On
January 12, C/2016 R2 was over 17 light-minutes from planet
Earth and nearly 24 light-minutes from the Sun.
Its blue tinted tail largely due to
CO+ gas
fluorescing in sunlight, the
head
or coma
of the comet appears with a slightly greenish hue,
likely emission from diatomic carbon.
APOD: 2017 December 9 - Stardust in Aries
Explanation:
This composition in
stardust
covers over 8 degrees on the northern sky.
The mosaicked field of view is west of the familiar Pleiades star cluster,
toward the zodiacal
constellation
Aries and the plane of our
Milky Way Galaxy.
At right in the deep skyscape is bluish Epsilon Arietis,
a star visible to the naked-eye and about 330 light-years away.
Reflecting starlight in the region,
dusty nebulae
LBN762, LBN753, and LBN743 sprawl
left to right
across the field, but are likely some 1,000 light-years away.
At that estimated distance, the cosmic canvas is over 140 light-years across.
Near the edge of a large
molecular
cloud, their dark interiors can hide newly
formed stars and young stellar objects
or protostars from prying optical telescopes.
Collapsing due to
self-gravity, the
protostars
form around dense cores embedded in the molecular cloud.
APOD: 2017 November 15 - NGC 7789: Caroline's Rose
Explanation:
Found among the rich starfields of the Milky Way,
star
cluster NGC 7789 lies about 8,000 light-years away
toward the constellation Cassiopeia.
A late 18th century
deep sky discovery of astronomer
Caroline Lucretia Herschel,
the cluster is also known as Caroline's Rose.
Its flowery
visual appearance
in small telescopes is created by
the cluster's nestled complex of stars and voids.
Now estimated to be 1.6 billion years young, the
galactic or open cluster of stars also shows its age.
All the stars in the cluster were likely born
at the same time, but the brighter and more massive ones have more
rapidly exhausted the hydrogen fuel in their
cores.
These have evolved from
main sequence
stars like the Sun into the many red giant stars shown with a
yellowish cast in this lovely color composite.
Using measured color and brightness,
astronomers can model the mass and hence the age of
the cluster stars just starting to "turn off" the main sequence
and become red giants.
Over 50 light-years across,
Caroline's Rose spans about
half a degree (the angular size of the Moon) near the center of
the
wide-field telescopic image.
APOD: 2017 October 2 - Two Comets and a Star Cluster
Explanation:
Two unusual spots are on the move near the famous Pleiades star cluster.
Shifting only a small amount per night,
these spots are actually
comets
in our nearby Solar System that by chance wandered
into the field of the
light-years distant stars.
On the far left is comet
C/2017 O1 ASAS-SN, a multi-kilometer
block of evaporating ice sporting a
bright coma of surrounding gas dominated by
green-glowing carbon.
Comet ASAS-SN1
shows a slight tail to its lower right.
Near the frame center is comet
C/2015 ER61 PanSTARRS,
also a giant block of
evaporating ice,
but sporting a rather
long tail to its right.
On the upper right is
the Pleiades, an
open cluster
dominated by bright blue stars illuminating
nearby reflecting dust.
This exposure, taken about two weeks ago,
is so deep that the filamentary interstellar dust can be traced across the
entire field.
The Pleiades is visible to the
unaided eye, but it should require binoculars to
see the comets.
APOD: 2017 September 13 - NGC 6334: The Cats Paw Nebula
Explanation:
Nebulas are perhaps as famous for being identified with familiar shapes as perhaps
cats are for getting into
trouble.
Still, no known cat could have created the vast
Cat's Paw Nebula visible in Scorpius.
At 5,500 light years distant, Cat's
Paw is an
emission nebula with a red color that originates from an abundance of
ionized
hydrogen atoms.
Alternatively known as the
Bear Claw Nebula or
NGC 6334,
stars nearly ten times the mass of our
Sun have been born
there
in only the past few million years.
Pictured here is
a deep field image of the
Cat's Paw
Nebula in light emitted by
hydrogen, oxygen, and
sulfur.
APOD: 2017 August 27 - The Heart Nebula in Hydrogen, Oxygen, and Sulfur
Explanation:
What powers the Heart Nebula?
The large emission nebula dubbed
IC 1805 looks, in whole, like a heart.
The nebula's glow -- as well as the shape of the gas and dust clouds -- is powered by
by stellar
winds and radiation from
massive hot stars in the nebula's newborn star cluster
Melotte 15.
This deep telescopic image maps the pervasive light of narrow
emission lines from atoms of
hydrogen,
oxygen, and
sulfur
in the nebula.
The field of view spans just over two
degrees on the sky,
so that it appears larger than four times the diameter of a full moon.
The cosmic heart is found in the constellation of
Cassiopeia, the boastful
mythical Queen of
Aethiopia .
APOD: 2017 June 30 - NGC 7814: The Little Sombrero in Pegasus
Explanation:
Point your telescope toward the high flying constellation
Pegasus
and you can find this
expanse
of Milky Way stars and distant galaxies.
Dominated by NGC 7814, the pretty
field of view would almost
be covered by a full moon.
NGC 7814 is
sometimes called the Little Sombrero for its
resemblance to the brighter more famous M104,
the Sombrero
Galaxy.
Both Sombrero and Little Sombrero are spiral galaxies
seen edge-on, and both have extensive halos and central
bulges cut by a thin disk with thinner dust lanes in silhouette.
In fact, NGC 7814
is some 40 million light-years away and an estimated 60,000 light-years
across.
That actually makes the
Little
Sombrero about the same physical size as
its better known namesake, appearing smaller and fainter
only because it is farther away.
Very faint dwarf galaxies,
potentially satellites of NGC
7814, have been discovered in deep exposures of the Little Sombrero.
APOD: 2017 June 27 - The M81 Galaxy Group through the Integrated Flux Nebula
Explanation:
Distant galaxies and nearby nebulas highlight this deep image of the
M81
Group of galaxies.
First and foremost in this 80-exposure mosaic is the
grand design spiral galaxy
M81, the largest galaxy in the image,
visible on the lower right.
M81 is
gravitationally interacting with
M82 just above it,
a large galaxy with an unusual halo of filamentary red-glowing gas.
Around the image many other galaxies from the
M81 Group of galaxies can be seen, as well as
many foreground Milky Way stars.
This whole
galaxy menagerie
is seen through the glow of an
Integrated
Flux Nebula (IFN), a vast and complex screen of diffuse gas and dust also in our
Milky Way Galaxy.
Details of the red and yellow
IFN, digitally enhanced, were imaged by a
new wide-field camera recently installed at the
Teide
Observatory in the
Canary Islands of
Spain.
APOD: 2017 June 24 - Markarian's Chain to Messier 64
Explanation:
Top to bottom,
this colorful and broad telescopic mosaic links
Markarian's Chain
of galaxies across the core of the Virgo Cluster to
dusty spiral galaxy Messier 64.
Galaxies are scattered through the field of view that spans some 20 full
moons across a gorgeous night sky.
The cosmic frame is also filled with foreground stars from
constellations Virgo and the well-groomed Coma Berenices, and
faint, dusty nebulae drifting above the plane of the Milky Way.
Look carefully for
Markarian's eyes.
The famous pair of interacting galaxies is near the top, not far
from M87,
the Virgo cluster's giant elliptical galaxy.
At the bottom, you can stare down
Messier 64, also known as the
Black Eye Galaxy.
The Virgo Cluster is the closest large galaxy cluster to our own
local
galaxy group.
Virgo
Cluster galaxies are about 50 million light-years distant,
but M64 lies a mere 17 million light-years away.
APOD: 2017 May 29 - Beneath Jupiter
Explanation:
Jupiter is stranger than we knew.
NASA's Juno spacecraft
has now completed its sixth swoop past
Jupiter
as it moves around its highly
elliptical orbit.
Pictured, Jupiter is seen
from below where, surprisingly, the horizontal
bands that cover most of the planet disappear into
swirls and complex patterns.
A line of
white oval clouds is visible nearer to the equator.
Recent results from
Juno
show that
Jupiter's
weather phenomena can extend deep below its cloud tops, and that
Jupiter's magnetic field
varies greatly with location.
Juno
is scheduled to orbit Jupiter 37 times with each orbit taking about six weeks.
APOD: 2017 March 30 - Young Stars and Dusty Nebulae in Taurus
Explanation:
This complex of dusty nebulae lingers along the edge of
the Taurus molecular cloud,
a mere 450 light-years distant.
Stars are forming on the
cosmic scene.
Composed from
almost 40 hours of image data, the 2 degree wide
telescopic field of view includes some youthful
T-Tauri class stars
embedded in the remnants of their natal clouds at the right.
Millions of years old and still going through stellar adolescence,
the
stars are variable in brightness and in the
late phases
of their gravitational collapse.
Their core temperatures will rise to sustain nuclear fusion
as they grow into stable, low mass, main sequence stars, a
stage of stellar evolution
achieved by our middle-aged Sun about 4.5 billion years ago.
Another youthful variable star, V1023 Tauri,
can be spotted on the left.
Within its yellowish dust cloud, it lies next to the
striking blue reflection nebula
Cederblad 30, also known as LBN 782.
Just above the bright bluish reflection nebula is dusty dark nebula
Barnard 7.
APOD: 2017 February 2 - NGC 1316: After Galaxies Collide
Explanation:
An example of violence on a cosmic scale, enormous
elliptical galaxy NGC 1316 lies about 75 million light-years away
toward Fornax,
the southern constellation of the Furnace.
Investigating
the startling sight, astronomers suspect the giant
galaxy of colliding with smaller neighbor NGC 1317 seen just
above, causing far flung loops and shells of stars.
Light from their close encounter would
have
reached Earth some 100 million years ago.
In
the deep, sharp image, the central regions of NGC 1316 and NGC 1317
appear separated by over 100,000 light-years.
Complex dust lanes visible within also indicate that NGC 1316
is itself the result of a merger of galaxies in the distant past.
Found on the outskirts of the
Fornax
galaxy cluster, NGC 1316 is known as Fornax A.
One of the visually brightest of the Fornax cluster galaxies it is one
of the strongest and
largest radio sources with radio emission
extending well beyond this telescopic field-of-view, over several
degrees on the sky.
APOD: 2017 January 14 - Stardust in the Perseus Molecular cloud
Explanation:
Clouds of stardust drift through this deep skyscape.
The cosmic scene spans nearly 2 degrees across the Perseus molecular
cloud some 850 light-years away.
A triangle of dusty nebulae
reflecting light from embedded stars
is captured in the telescopic field of view.
With a characteristic bluish color
reflection nebula NGC 1333 is at left,
vdB13 at bottom right, and rare yellowish reflection nebula
vdB12 lies at the top.
Stars are forming
in the Perseus molecular cloud, though most
are obscured at visible wavelengths by the pervasive dust.
Still, hints of contrasting red emission from Herbig-Haro objects, the
jets and shocked glowing gas emanating from recently formed stars,
are evident
in NGC 1333.
At the estimated distance of the molecular cloud, legs of the triangle
formed by the reflection nebulae would be about 20 light-years long.
APOD: 2017 January 4 - Clouds of Andromeda
Explanation:
The beautiful Andromeda Galaxy is often imaged by
planet Earth-based astronomers.
Also known as M31, the nearest large spiral galaxy is a familiar sight
with dark dust lanes, bright yellowish core, and
spiral arms traced by
blue starlight.
A mosaic of well-exposed broad and narrow-band image data, this
colorful,
premier portrait of our
neighboring island universe
offers strikingly unfamiliar
features though, faint reddish clouds of glowing
ionized hydrogen gas in the same wide field of view.
Still, the ionized hydrogen clouds likely
lie in the foreground of the scene, well within our Milky Way Galaxy.
They could be associated with the pervasive, dusty
interstellar cirrus
clouds scattered hundreds of light-years above our own galactic plane.
If they were located at the 2.5 million light-year distance of the
Andromeda Galaxy they would be enormous,
since the Andromeda Galaxy itself is 200,000 or so light-years across.
APOD: 2016 September 30 - Lynds Dark Nebula 1251
Explanation:
Stars are forming in Lynds Dark Nebula
(LDN) 1251.
About 1,000 light-years away, the dusty molecular cloud
is part of a complex of dark nebulae mapped toward the
Cepheus flare
region, drifting above the plane of our Milky Way galaxy.
Across the spectrum,
astronomical explorations of the obscuring
interstellar clouds reveal energetic shocks and outflows
associated with newborn stars, including the telltale reddish glow from
scattered
Herbig-Haro objects seen in this sharp image.
Distant background galaxies also lurk on the scene,
visually buried behind the dusty expanse.
The deep telescopic field of view spans about
two full moons on the sky, or 17 light-years at the
estimated distance of LDN 1251.
APOD: 2016 September 6 - The Whirlpool Galaxy and Beyond
Explanation:
Follow the handle of
the Big Dipper
away from the dipper's bowl, until
you get to the handle's last bright star.
Then, just slide your telescope a little south and west and
you might find this
stunning pair of interacting galaxies,
the 51st entry
in Charles
Messier's famous
catalog.
Perhaps the original
spiral nebula, the large galaxy with
well defined spiral structure is also cataloged as
NGC 5194.
Its spiral arms and dust lanes
clearly sweep in front of its companion galaxy (left),
NGC 5195.
The pair are
about 31 million light-years distant and
officially lie within the angular boundaries of the small constellation
Canes Venatici.
Though M51
looks faint and fuzzy to the human eye,
the above long-exposure, deep-field image
taken earlier this year shows much of the
faint complexity that actually surrounds the smaller galaxy.
Thousands of the faint dots in background of the featured image are actually
galaxies far across the universe.
APOD: 2016 August 17 - Meteor before Galaxy
Explanation:
What's that green streak in front of the Andromeda galaxy?
A meteor.
While photographing the
Andromeda galaxy last Friday,
near the peak of the
Perseid
Meteor
Shower, a sand-sized rock from deep space
crossed right in front of our
Milky Way Galaxy's far-distant companion.
The small
meteor
took only a fraction of a second to pass through this 10-degree field.
The meteor flared
several times while braking violently upon entering
Earth's atmosphere.
The green color
was created, at least in part, by the meteor's gas glowing as it vaporized.
Although the exposure was timed to catch a
Perseids meteor,
the orientation of the imaged streak seems a better match to a meteor from the
Southern Delta Aquariids, a
meteor shower that peaked a few weeks earlier.
APOD: 2016 August 4 - M63: Sunflower Galaxy Wide Field
Explanation:
The Sunflower Galaxy blooms near the center of this
wide
field telescopic view.
The scene spans about 2 degrees or 4 full moons on the
sky toward the loyal constellation
Canes
Venatici.
More formally known as Messier 63, the majestic
island universe
is nearly 100,000 light-years across, about the size
of our own Milky Way Galaxy.
Surrounding its bright yellowish core, sweeping spiral arms are streaked
with cosmic dust lanes and dotted with star forming regions.
A dominant member of a known
galaxy
group, M63 has faint,
extended features that could be the
the remains of dwarf satellite galaxies, evidence that
large
galaxies grow by accreting small ones.
M63 shines across the electromagnetic spectrum and is thought to have
undergone
bursts of intense
star formation.
APOD: 2016 July 25 - Deep Magellanic Clouds Image Indicates Collisions
Explanation:
Did the two most famous satellite galaxies of our Milky Way Galaxy once collide?
No one knows for sure, but a
detailed inspection of deep images like that
featured here give an indication that they have.
Pictured, the Large Magellanic Cloud (LMC) is on the top left and the
Small Magellanic Cloud (SMC) is on the bottom right.
The surrounding field is monochrome color-inverted to highlight faint filaments, shown in gray.
Perhaps surprisingly, the
featured research-grade image was compiled with small telescopes to cover the large angular field -- nearly 40 degrees across.
Much of the faint nebulosity is
Galactic Cirrus clouds of thin dust in our own Galaxy,
but a faint stream of stars does appear to be extending from the
SMC toward the
LMC.
Also, stars surrounding the LMC appear asymmetrically distributed, indicating in
simulations that they could well have been pulled off gravitationally in one or more collisions.
Both the LMC and the SMC are visible to the unaided eye in southern skies.
Future telescopic
observations and computer simulations are sure to continue in a continuing effort to better understand the history of
our Milky Way and its surroundings.
APOD: 2016 June 28 - Juno Mission Trailer
Explanation:
What will NASA's Juno spacecraft find when it reaches Jupiter next Monday?
Very little, if
Juno does not survive
Jupiter Orbit Insertion,
a complex series of operations in an unknown environment just above Jupiter's cloud tops.
If successful, as explained in the
featured video,
Juno will swoop around Jupiter, passing closer than any previous spacecraft.
The goal is to decelerate, enter into a highly
elliptical orbit,
and begin two years of science operations.
Juno's science mission objectives include mapping Jupiter's deep structure, determining how much water is in Jupiter's atmosphere, and exploring Jupiter's powerful magnetic field and how it creates
auroras around Jupiter's poles.
These lessons
hold promise to help humanity better understand the history of our Solar System and the dynamics of our Earth.
Juno is powered predominantly by three
large solar panels,
each measuring a side of small truck.
Launched in 2011, Juno's planned mission will take it around the Jovian giant 37 times, after which, to avoid contaminating
Europa with microbes,
it will be directed to
dive into Jupiter's
thick atmosphere, where it will break apart and melt.
APOD: 2016 May 6 - NGC 7023: The Iris Nebula
Explanation:
These cosmic clouds have blossomed 1,300 light-years away,
in the fertile starfields of the
constellation
Cepheus.
Called the Iris Nebula,
NGC 7023
is not the only nebula
to evoke the imagery of flowers, though.
Still, this
deep telescopic image
shows off the Iris Nebula's range of
colors and symmetries, embedded in surrounding
fields of interstellar dust.
Within the Iris itself, dusty nebular material surrounds a hot,
young star.
The dominant color of the brighter reflection nebula is blue,
characteristic
of dust grains reflecting starlight.
Central
filaments of the reflection nebula glow with a faint reddish
photoluminesence as some dust grains
effectively
convert the star's invisible
ultraviolet radiation to visible red light.
Infrared observations
indicate that this nebula contains
complex carbon molecules known as
PAHs.
The pretty blue petals of the Iris Nebula span about six light-years.
The colorful field-of-view stretches almost five Full Moons
across the sky.
APOD: 2016 April 28 - A Dust Angel Nebula
Explanation:
The combined light of
stars along the Milky Way
are reflected by these cosmic dust clouds that soar
some 300 light-years or so above the plane of our galaxy.
Dubbed the
Angel
Nebula, the faint apparition is part of an expansive complex
of dim and relatively
unexplored,
diffuse molecular clouds.
Commonly found at high galactic latitudes, the dusty galactic cirrus
can be traced over large regions toward the North and South Galactic poles.
Along with the refection of starlight, studies indicate
the dust clouds produce a faint
reddish
luminescence, as interstellar
dust grains convert invisible ultraviolet radiation to visible red light.
Also capturing nearby Milky Way stars and an array of
distant background galaxies, the deep, wide-field 3x5 degree
image spans about 10 Full Moons
across planet Earth's sky
toward the constellation Ursa Major.
APOD: 2016 March 24 - Hickson 91 in Piscis Austrinus
Explanation:
Scanning the skies for galaxies, Canadian astronomer
Paul Hickson and colleagues identified some 100 compact
groups
of galaxies, now appropriately called
Hickson Compact Groups (HCGs).
This sharp telescopic image
captures one such galaxy group,
HCG 91, in beautiful detail.
The group's three colorful spiral galaxies at the
center of the field of view are locked in
a gravitational tug of war,
their interactions producing faint but visible
tidal tails over 100,000 light-years long.
Their close encounters trigger
furious star formation.
On a cosmic timescale the
result
will be a merger into a large single galaxy,
a process now understood to be a normal part of the
evolution of galaxies, including
our own Milky Way.
HCG 91 lies about 320 million light-years away in
the constellation
Piscis
Austrinus.
But the impressively
deep
image also catches evidence of fainter tidal
tails and galaxy interactions close to 2 billion light-years distant.
APOD: 2016 January 23 - Big Dipper, Deep Sky
Explanation:
The Big Dipper
is an easy to recognize, well-known asterism in
northern skies, though many see the
Plough
or Wagon.
Famous bright nebulae of the north can also be found along
its familiar lines, highlighted in this carefully
composed scene with telescopic insets framed in the wider-field
skyview.
All from
Messier's
catalog,
M101 and
M51 are cosmic pinwheel and
whirlpool on the left, spiral galaxies far beyond the Milky Way.
To the right, M108,
a distant edge-on spiral galaxy is seen
close to our galaxy's own
owl-faced planetary nebula M97.
Taken
on January 16, the wider-field view seems to include
an extra star along the Dipper's handle, though.
That's Comet Catalina
(C/2013
US10) now sweeping through
northern nights.
APOD: 2016 January 6 - Comets and Bright Star
Explanation:
This
timely, telescopic, two panel mosaic spans about 10 full moons
across planet Earth's predawn skies.
Recorded as the year began from Tenerife, Canary Islands,
near the top of the frame are the faint coma and tail of
Comet
Borrelly (P/19).
A comet with a seven year orbital period,
Borrelly's nucleus
was visited by the ion propelled spacecraft
Deep Space 1 near
the beginning of the 21st century.
Anchoring the scene at the bottom is brilliant star Arcturus
(Alpha Bootes) and
Comet
Catalina (C/2013 US10) a
first time visitor from the Oort Cloud.
Catalina's
yellowish dust tail extends below and right.
Buffeted by winds and storms from the Sun,
the comet's complex ion tail sweeps up and toward the right,
across most of the field of view.
Remarkably, one of the composition's 30 second exposure subframes
also caught the trail of a bright meteor, slashing toward the left
between comets and bright star.
APOD: 2015 December 1 - Nebulae in Auriga
Explanation:
Rich in star clusters and nebulae, the ancient
constellation of the Charioteer
(Auriga)
rides high in northern winter night skies.
Composed from narrow and broadband filter data and
spanning nearly 8 Full Moons (4 degrees) on the sky,
this deep telescopic view shows off some of Auriga's celestial bounty.
The field includes emission region
IC 405 (top left) about 1,500
light-years distant.
Also known as the Flaming Star Nebula,
its red, convoluted clouds of glowing hydrogen gas are energized by hot
O-type star
AE Aurigae.
IC 410 (top right)
is significantly more distant, some 12,000 light-years away.
The star forming region is famous for its embedded young star cluster,
NGC 1893,
and tadpole-shaped clouds of dust and gas.
IC 417 and NGC 1931 at the lower right,
the Spider and the Fly, are also young star
clusters embedded in natal clouds that lie far beyond IC 405.
Star cluster NGC 1907
is near the bottom edge of the frame, just right of center.
The crowded field of view looks along the plane of our
Milky Way
galaxy, near the direction of the
galactic anticenter.
APOD: 2015 November 23 - A 212 Hour Exposure of Orion
Explanation:
The constellation of Orion is much more than three stars in a row.
It is a direction in space that is
rich with impressive nebulas.
To better appreciate this well-known swath of sky, an
extremely long exposure was taken over many clear nights in 2013 and 2014.
After 212 hours of camera time and an
additional year of processing, the featured 1400-exposure collage spanning over 40 times the
angular diameter of
the Moon emerged.
Of the many interesting details that have become visible, one that particularly draws the eye is
Barnard's Loop, the bright red circular filament arcing down from the middle.
The Rosette Nebula is not the giant red nebula near the top of the image -- that is a larger but lesser known nebula known as Lambda Orionis.
The Rosette Nebula is visible, though: it is the red and white nebula on the upper left.
The bright orange star just above the frame center is
Betelgeuse, while the bright blue star on the lower right is
Rigel.
Other famous nebulas visible include
the Witch Head Nebula,
the Flame Nebula,
the Fox Fur Nebula, and, if you know just where to look,
the comparatively small Horsehead Nebula.
About those
famous three stars that cross the belt of
Orion the Hunter --
in this busy frame they can be hard to locate, but a
discerning eye will find them just below and to the right of the image center.
APOD: 2015 October 29 - IC 1871: Inside the Soul Nebula
Explanation:
This
cosmic close-up looks deep inside the Soul Nebula.
The dark and brooding dust clouds outlined by bright
ridges of glowing gas are cataloged as IC 1871.
About 25 light-years across,
the telescopic field of view spans only
a small part of the much larger
Heart and Soul nebulae.
At an estimated distance of 6,500 light-years the star-forming
complex lies within the Perseus spiral arm
of the Milky Way, seen in planet
Earth's skies toward the constellation Cassiopeia.
An example of
triggered star formation,
the dense star-forming clouds of IC 1871 are themselves
sculpted by the intense winds and radiation of the region's
massive young stars.
This color image adopts a
palette made popular in Hubble images
of star-forming regions.
APOD: 2015 October 12 - Galaxy, Stars, and Dust
Explanation:
Spiky stars and spooky shapes abound in
this deep cosmic skyscape.
Its well-composed field of view covers
about a Full Moon on the
sky toward the constellation Pegasus.
Of course the brighter stars show
diffraction spikes, the commonly
seen effect of internal
supports
in reflecting telescopes, and lie
well within our own
Milky Way galaxy.
The faint but pervasive clouds of interstellar dust
ride above the galactic plane and dimly reflect the
Milky Way's
combined starlight.
Known as high latitude cirrus or integrated flux nebulae they are
associated with molecular clouds.
In this case, the diffuse cloud cataloged as
MBM 54,
less than a thousand light-years distant, fills the scene.
The galaxy seemingly tangled in the dust is the striking spiral galaxy NGC 7497
some 60 million light-years away.
Seen almost edge-on
near the center of the field,
NGC 7497's own spiral arms and dust lanes echo the colors of the
Milky Way's stars and dust.
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 January 29 - Close Encounter with M44
Explanation:
On Monday, January 26, well-tracked
asteroid
2004 BL86 made its
closest approach, a mere 1.2 million kilometers from our fair planet.
That's about 3.1 times the Earth-Moon distance or 4 light-seconds
away.
Moving quickly through Earth's night sky, it left this streak
in a 40 minute long exposure on January 27 made from Piemonte, Italy.
The remarkably pretty telescopic field of view includes
M44, also known as the Beehive
or Praesepe star cluster in Cancer.
Of course, its close encounter with M44 is only an apparent one,
with the cluster nearly along the same line-of-sight to the
near-earth asteroid.
The actual distance between star cluster and
asteroid
is around 600 light-years.
Still, the close approach to planet Earth allowed
detailed radar imaging from NASA's Deep Space Network antenna
at Goldstone, California and revealed the
asteroid
to have its own moon.
APOD: 2015 January 17 - Comet Lovejoy's Tail
Explanation:
Sweeping north
in planet Earth's sky, Comet Lovejoy's greenish coma
and blue tinted ion tail stretched across this
field of stars in
the constellation Taurus on January 13.
The inset at the upper left shows the 1/2 degree angular size of
the full moon for scale.
So Lovejoy's coma appears only a little smaller (but much fainter)
than a full moon on the sky, and its tail is visible
for over 4 degrees across the frame.
That corresponds to over 5 million kilometers
at the comet's estimated distance of 75 million kilometers
from Earth.
Blown by the solar wind, the comet's tenuous, structured
ion tail streams
away from the Sun, growing as
this Comet Lovejoy
heads toward perihelion, its closest approach to the Sun, on January 30.
While diatomic carbon
(C2) gas fluorescing in sunlight
produces the coma's green color, the fainter bluish tail is tinted by
emission from ionized carbon monoxide (CO+).
APOD: 2015 January 14 - The Hunter, the Bull, and Lovejoy
Explanation:
Heading north, Comet Lovejoy (C/2014 Q2)
is putting on its best show for
comet
watchers now, with moonlight absent from mid-January's
early evening skies.
An easy binocular target and just visible to the unaided eye from
dark sites, the comet sweeps across the constellation Taurus the Bull
in this deep night skyscape.
The starry scene was captured just two days ago on
January 12, from Jackson Hole, Wyoming,
planet Earth.
In fact, the head of Taurus formed by the V-shaped
Hyades star
cluster points toward Lovejoy at the right.
The comet's greenish coma and tail streaming in the anti-sunward
direction also seem to have been shot
from Orion's bow.
You can spot the
familiar
stars of the nebula rich constellation of the Hunter on the left, and
follow this link
to highlight Comet Lovejoy in the wide field of view.
APOD: 2014 August 13 - Rings Around the Ring Nebula
Explanation:
It is a familiar sight to sky enthusiasts with even a small telescope.
There is much more to the
Ring Nebula (M57),
however, than can be seen through a
small telescope.
The easily visible
central ring is about one
light-year across,
but this remarkably deep exposure -
a collaborative effort combining data from three different large telescopes -
explores
the looping filaments
of glowing gas extending much farther from the nebula's
central star.
This remarkable
composite image includes narrowband hydrogen image,
visible light emission, and
infrared light emission.
Of course, in this
well-studied
example of a
planetary nebula,
the glowing material does not come from planets.
Instead, the
gaseous shroud represents outer layers
expelled from a dying, sun-like star.
The Ring Nebula is about 2,000 light-years away toward the musical
constellation
Lyra.
APOD: 2014 June 18 - NGC 6334: The Cat's Paw Nebula
Explanation:
Nebulas are perhaps as famous for being identified with familiar shapes as perhaps
cats are for getting into
trouble.
Still, no known cat could have created the vast
Cat's Paw Nebula visible in Scorpius.
At 5,500 light years distant, Cat's
Paw is an
emission nebula with a red color that originates from an abundance of ionized
hydrogen atoms.
Alternatively known as the
Bear Claw Nebula or
NGC 6334,
stars nearly ten times the mass of our
Sun have been born
there
in only the past few million years.
Pictured above is
a deep field image of the
Cat's Paw
nebula.
APOD: 2014 June 12 - The Tarantula Zone
Explanation:
The
Tarantula Nebula is more than 1,000 light-years in diameter,
a giant star forming region within our neighboring galaxy
the Large Magellanic Cloud (LMC).
That cosmic arachnid lies toward the upper left in this deep and
colorful
telescopic view made through broad-band and
narrow-band filters.
The image spans nearly 2 degrees (4 full moons) on the sky and
covers a part of the LMC over 8,000 light-years across.
Within the Tarantula (NGC 2070), intense radiation,
stellar winds and supernova shocks from the central young cluster of massive
stars, cataloged as R136,
energize the nebular glow and shape the spidery filaments.
Around the Tarantula
are other violent star-forming regions with
young star clusters, filaments, and
bubble-shaped clouds
In fact, the frame includes the
site of the closest supernova in modern times,
SN 1987A,
just above center.
The rich field of view is located in the southern
constellation
Dorado.
APOD: 2014 June 5 - Hubble Ultra Deep Field 2014
Explanation:
Galaxies like colorful pieces of candy fill the
Hubble Ultra Deep Field 2014.
The dimmest galaxies are more than 10 billion times fainter than
stars visible to the unaided eye and represent the
Universe in
the extreme past, a few 100 million years after the
Big Bang.
The image itself
was made with the significant addition
of ultraviolet data to the Hubble Ultra Deep Field,
an update of Hubble's
famous
most distant gaze toward the southern constellation of Fornax.
It now covers the entire range of wavelengths available to
Hubble's cameras, from ultraviolet through visible to near-infrared.
Ultraviolet data adds the crucial capability of studying
star formation in the
Hubble Ultra
Deep Field galaxies between 5 and 10 billion light-years distant.
APOD: 2014 March 22 - Martian Chiaroscuro
Explanation:
Deep shadows create
dramatic contrasts between light and dark in
this
high-resolution close-up of the martian surface.
Recorded on January 24 by the HiRISE camera onboard the
Mars Reconnaissance Orbiter, the scene
spans about 1.5 kilometers across a sand dune field in a
southern highlands crater.
Captured when the Sun was just 5 degrees above the local horizon,
only the dune crests are caught in full sunlight.
With the long, cold winter approaching the red planet's southern
hemisphere, bright ridges of
seasonal
frost line the martian dunes.
APOD: 2014 February 14 - IC 1805: Light from the Heart
Explanation:
Sprawling across almost 200 light-years,
emission
nebula IC 1805
is a mix of glowing interstellar gas and dark dust clouds
about 7,500 light-years away in the Perseus
spiral arm of our galaxy.
Stars were born in this region
whose nickname, the Heart Nebula, derives from its
Valentine's-Day-appropriate shape.
The clouds themselves are shaped by stellar winds and radiation from
massive hot stars in the nebula's newborn star cluster
Melotte 15 about 1.5 million years young.
This
deep telescopic image
maps the pervasive light of narrow
emission lines
from atoms in the nebula to a color
palette made popular
in Hubble images of star forming regions.
The field of view spans about two degrees
on the sky or four times the diameter of a full moon.
The cosmic heart is found in the constellation of
Cassiopeia, the boastful
mythical Queen of
Aethiopia .
APOD: 2014 February 13 - Downtown Auriga
Explanation:
Rich in star clusters and nebulae, the ancient
constellation
of Auriga, the Charioteer,
rides high in northern winter night skies.
Spanning nearly 24 full moons (12 degrees) on the sky,
this
deep telescopic mosaic view recorded in January
shows off some of Auriga's most popular sights for cosmic tourists.
The crowded field sweeps along the plane of our
Milky Way galaxy in the
direction opposite
the galactic center.
Need
directions?
Near the bottom of the frame, at the Charioteer's boundary with Taurus
the Bull, the bright bluish
star Elnath
is known as both Beta Tauri and Gamma Aurigae.
On the far left and almost 3000 light-years away, the busy,
looping filaments of supernova remnant
Simeis 147 cover about 150 light-years.
Look toward the right to find emission nebula
IC 410,
significantly more distant, some 12,000 light-years away.
Star forming IC 410 is famous for
its embedded young star cluster, NGC 1893,
and tadpole-shaped clouds of dust and gas.
The Flaming Star Nebula, IC 405,
is just a little farther along.
Its red, convoluted clouds
of glowing hydrogen gas are energized by hot O-type star AE Aurigae.
Two of our galaxy's open star clusters, Charles Messier's
M36
and M38 line up in the
starfield above,
familiar to many binocular-equipped skygazers.
APOD: 2014 February 1 - NGC 6188 and NGC 6164
Explanation:
Fantastic shapes
lurk in clouds of glowing gas in
NGC 6188, about 4,000 light-years away.
The emission nebula is found near the edge of a
large molecular cloud unseen at visible wavelengths, in the southern
constellation
Ara.
Massive, young
stars of the embedded Ara
OB1 association
were formed in that region only a few million years ago,
sculpting the dark shapes and
powering the nebular glow with
stellar winds and intense ultraviolet radiation.
The recent
star
formation itself was likely triggered by
winds and supernova explosions, from previous generations of massive
stars, that swept up and compressed the molecular gas.
Joining NGC 6188 on this cosmic canvas
is rare emission nebula NGC 6164,
also created by one of the region's massive O-type stars.
Similar in appearance to many
planetary nebulae, NGC 6164's striking,
symmetric gaseous shroud and faint halo surround
its bright central star near the bottom edge.
The impressively
wide field of view
spans over 3 degrees (six full Moons), corresponding to
over 200 light years at the estimated distance
of NGC 6188.
Narrowband image data has been included in
the natural
looking color composite, adding to deep
red emission from hydrogen and sulfur atoms and the blue-green light
of oxygen atoms.
APOD: 2013 December 12 - Alnitak, Alnilam, Mintaka
Explanation:
Alnitak,
Alnilam,
and
Mintaka,
are the bright bluish stars
from east to west (lower right to upper left) along the diagonal in
this gorgeous cosmic vista.
Otherwise known as the
Belt of Orion, these
three blue supergiant stars are hotter and much more
massive than the Sun.
They lie about 1,500 light-years away, born
of Orion's well-studied interstellar clouds.
In fact, clouds of gas and dust adrift in this region have
intriguing and some surprisingly familiar shapes, including the
dark Horsehead Nebula
and Flame Nebula near
Alnitak at the lower right.
The famous Orion Nebula
itself is off the right edge of this colorful star field.
The well-framed, wide-field telescopic image
spans about 4 degrees on the sky.
APOD: 2013 October 26 - NGC 7789: Caroline's Rose
Explanation:
Found among the rich starfields of the Milky Way toward the
constellation Cassiopeia,
star
cluster NGC 7789 lies about 8,000 light-years away.
A late 18th century
deep sky discovery of astronomer
Caroline Lucretia Herschel,
the cluster is also known as Caroline's Rose.
Its suggestive appearance is created by the cluster's nestled
complex of stars and voids.
Now estimated to be 1.6 billion years young, the
galactic or open cluster of stars also shows its age.
All the stars in the cluster were likely born
at the same time, but the brighter and more massive ones have more
rapidly exhausted the hydrogen fuel in their
cores.
These have evolved from
main sequence
stars like the Sun into the many red giant stars shown with a
yellowish cast in this lovely color composite.
Using measured
color and brightness, astronomers
can model the mass and hence the age of
the cluster stars just starting to "turn off" the main sequence
and become red giants.
Over 50 light-years across,
Caroline's Rose spans about
half a degree (the angular size of the moon)
near the center of the wide-field telescopic image.
APOD: 2013 October 25 - NGC 7814: The Little Sombrero in Pegasus
Explanation:
Point your telescope toward the high flying
constellation
Pegasus
and you can find this
expanse of Milky Way stars and distant galaxies.
Centered on NGC 7814, the pretty
field of view
would almost
be covered by a full moon.
NGC 7814 is
sometimes called the Little Sombrero for its
resemblance to the brighter more famous M104,
the Sombrero Galaxy.
Both Sombrero and Little Sombrero are spiral galaxies
seen edge-on, and both have extensive central
bulges cut by a thinner disk with dust lanes in silhouette.
In fact, NGC 7814
is some 40 million light-years away and an
estimated 60,000 light-years across.
That actually makes the Little Sombrero about the same physical size as
its better known namesake, appearing to be smaller and fainter
only because it is farther away.
A very faint dwarf galaxy,
potentially a satellite of NGC 7814,
is revealed in the deep exposure just below the Little Sombrero.
APOD: 2013 October 16 - Three Galaxies in Draco
Explanation:
This intriguing trio of galaxies is sometimes
called the Draco Group, located in the northern
constellation of (you guessed it)
Draco.
From left to right are
edge-on spiral NGC 5981,
elliptical galaxy NGC 5982, and
face-on spiral NGC 5985 --
all within this single telescopic
field of view spanning a little more than
half the width of the full moon.
While the group is far too small to be a
galaxy cluster
and has not been
catalogued
as a compact group, these galaxies all do lie roughly
100 million light-years from planet Earth.
On close examination with spectrographs, the bright core of the
striking face-on spiral NGC 5985 shows
prominent emission in specific wavelengths of light, prompting
astronomers to classify it as a
Seyfert, a type of active galaxy.
Not as well known as other tight
groupings of galaxies,
the contrast in visual appearance
makes this triplet an attractive subject for
astrophotographers.
This
impressively
deep exposure hints at faint, sharp-edged shells surrounding
elliptical NGC 5982, evidence of past galactic mergers.
It also reveals many even more distant
background galaxies.
APOD: 2013 August 27 - A Flight through the Hubble Ultra Deep Field
Explanation:
What would it look like to fly through the distant universe?
To find out, a team of astronomers estimated the relative distances
to over 5,000 galaxies in one of the most distant fields of galaxies ever imaged: the
Hubble Ultra Deep Field
(HUDF).
Because it takes light a long time to cross the universe, most galaxies visible in the
above video
are seen when the universe was only a fraction of its current age, were
still forming, and have unusual shapes when compared to modern galaxies.
No mature looking spiral galaxies such as our
Milky Way or the
Andromeda galaxy yet exist.
Toward the end of the video the
virtual observer flies past the farthest galaxies in the
HUDF field, recorded to have a
redshift past 8.
This early class of low luminosity
galaxies
likely contained
energetic stars emitting light that
transformed much of the
remaining normal matter in the universe from a cold gas to a hot ionized
plasma.
APOD: 2013 July 20 - Comet Lemmon and the Deep Sky
Explanation:
Now sweeping
high above the ecliptic plane,
Comet Lemmon
has faded dramatically in
planet Earth's night sky
as it heads for the outer solar system.
Some 16 light-minutes (2 AU) from the Sun, it still sports a
greenish coma though, posing on the right
in this 4 degree wide
telescopic view from
last Saturday with deep sky star clusters and nebulae
in Cassiopeia.
In fact, the rich background skyscape is
typical within the boundaries of the
boastful northern
constellation that lie along the crowded starfields of the Milky Way.
Included near center is open
star cluster M52
about 5,000 light-years away.
Around 11,000 light-years distant, the red glowing nebula NGC 7635
below and left of M52 is well-known for its appearance in close-up
images as the Bubble Nebula.
But the fading Comet Lemmon is not the only foreground object on
the scene.
A faint streak on the right is an orbiting satellite
caught crossing through the field during the long exposure, glinting
in the sunlight and winking out as it
passes into Earth's shadow.
APOD: 2013 May 31 - The Eagle and The Swan
Explanation:
The Eagle Nebula and the Swan Nebula span
this
broad starscape, a telescopic view of the
Sagittarius
spiral arm toward the center of our Milky Way galaxy.
The Eagle, also known as M16, is left, above center, and the Swan,
or M17 at the lower right.
The deep, wide-field image shows the cosmic clouds as
brighter regions of active star-formation.
They lie along the spiral arm suffused with
reddish emission charactistic of
atomic hydrogen gas, and dusty dark nebulae.
In fact, the center of both nebulae are locations of well-known
close-up images of
star formation
from the Hubble Space Telescope.
M17, also called the Omega Nebula, is about 5500 light-years away,
while M16 is some 6500 light-years distant.
In the frame that covers 3 degrees across the sky, the extended wings
of the Eagle Nebula are spread over 120 light-years.
APOD: 2012 November 23 - The Pipe Nebula
Explanation:
East of Antares,
dark markings sprawl through crowded
star fields toward the center
of our Milky Way Galaxy.
Cataloged in the early 20th
century by astronomer
E. E. Barnard, the obscuring
interstellar dust clouds
include
B59, B72, B77 and B78, seen in silhouette
against the starry background.
Here, their combined shape suggests
a pipe
stem and bowl,
and so the dark nebula's popular name is the Pipe Nebula.
The deep and expansive view was represents nearly 24 hours of
exposure time recorded in very dark skies of the Chilean
Atacama desert.
It covers a full 10 by 10 degree field in the
pronounceable
constellation Ophiuchus.
The Pipe Nebula is part of the Ophiuchus dark cloud complex
located at a distance of about 450 light-years.
Dense cores
of gas and dust within the Pipe Nebula are collapsing to form stars.
APOD: 2012 October 14 - The Hubble Extreme Deep Field
Explanation:
What did the first galaxies look like?
To help answer this question, the Hubble Space Telescope has just finished taking the
eXtreme Deep Field (XDF), the deepest image of the universe ever taken in
visible light.
Pictured above, the XDF shows a sampling of some of the
oldest galaxies ever seen,
galaxies that formed just after the
dark ages, 13 billion years ago, when the universe was
only a few percent of its present age.
The Hubble Space Telescope's
ACS camera and the infrared channel
of the WFPC3 camera took
the image.
Combining efforts spread over 10 years, the
XDF is more sensitive, in some colors,
than the original Hubble Deep Field (HDF), the
Hubble Ultra Deep Field (HUDF) completed in 2004, and the
HUDF Infrared completed in 2009.
Astronomers the world over will likely study the
XDF for years to come to
better understand how stars and galaxies formed in the early universe.
APOD: 2012 October 13 - Galaxies, Stars, and Dust
Explanation:
Spiky stars and spooky shapes abound in
this
deep cosmic skyscape.
Its well-composed field of view covers
about 2 Full Moons on the
sky toward the constellation Pegasus.
Of course the brighter stars show diffraction spikes, the commonly
seen effect of internal
supports
in reflecting telescopes, and lie
well within our own Milky Way galaxy.
The faint but pervasive clouds of interstellar dust
ride above the galactic plane and dimly reflect the
Milky Way's
combined starlight.
Known as high latitude cirrus or integrated flux nebulae they are
associated with molecular clouds.
In this case, the diffuse cloud cataloged as
MBM 54,
less than a thousand light-years distant, fills the scene.
Other galaxies far beyond the Milky Way are visible through the
ghostly apparitions, including the striking spiral galaxy NGC 7497
some 60 million light-years away.
Seen almost edge-on
near the center of the field,
NGC 7497's own spiral arms and dust lanes echo the colors of the
Milky Way's stars and dust.
APOD: 2012 February 24 - Aurigae Nebulae
Explanation:
Rich in star clusters and nebulae, the ancient
constellation
of Auriga, the Charioteer,
rides high in northern winter night skies.
Composed from narrow and broadband filter data and
spanning nearly 8 Full Moons (4 degrees) on the sky,
this
deep telescopic view recorded in January
shows off some of Auriga's celestial bounty.
The field includes emission region IC 405 (top left) about 1,500
light-years distant.
Also known as the Flaming Star Nebula,
its red, convoluted clouds
of glowing hydrogen gas are energized by hot O-type star AE Aurigae.
IC 410 (top right)
is significantly more distant, some 12,000 light-years away.
The star forming region is famous for
its embedded young star cluster, NGC 1893,
and tadpole-shaped clouds of dust and gas.
IC 417 and NGC 1931 at the lower right,
the Spider and the Fly, are also young star
clusters embedded in natal clouds that lie far beyond IC 405.
Star cluster NGC 1907
is near the bottom edge of the frame, just right of center.
The crowded field of view looks along the plane of our
Milky Way
galaxy, near the direction of the
galactic anticenter.
APOD: 2011 December 23 - Shell Galaxy NGC 7600
Explanation:
Similar in size to the Milky Way,
elliptical galaxy NGC 7600 is about 160 million light-years distant.
In
this deep image, spanning about 1/2 degree on
the sky
toward the constellation Aquarius, NGC 7600 sports a remarkable
outer halo of nested shells and broad circumgalactic structures.
The tantalizing features can be explained by
the accretion of
dark matter and stars on
a cosmic timescale.
In fact, a movie generated by simulating galaxy formation using a
cosmological model with
cold
dark matter for the halos of merging galaxies
reproduces the appearance of NGC 7600 in amazing detail.
The remarkable simulation movie is
available here on Vimeo and
here in other
formats.
It presents compelling evidence that detailed features of
galaxy mergers observed with small, wide
field telescopes on planet Earth, are natural consequences of
galaxy formation and fundamental
properties of dark matter.
APOD: 2011 November 28 - A Landslide on Asteroid Vesta
Explanation:
Asteroid Vesta is home to some of the most impressive cliffs in the Solar System.
Pictured above near the image center is a very
deep cliff running about 20 kilometers from top to bottom.
The image was taken by the
robotic Dawn spacecraft
that began orbiting the
500-kilometer space rock earlier this year.
The topography of the
scarp
and its surroundings indicates that huge landslides may have occurred
down this slope.
The scarp's origin remains unknown, but parts of the cliff face itself must be quite old as several craters have appeared in it since it was created.
Dawn has now finished up its high altitude mapping survey and will spiral down to a lower altitude orbit to better explore the asteroid's
gravitational field.
During 2012,
Dawn is scheduled to blast away from
Vesta and begin a long journey to the only asteroid belt object known to be larger:
Ceres.
APOD: 2011 September 21 - Pleiades Deep Field
Explanation:
Have you ever seen the Pleiades star cluster?
Even if you have, you probably have never seen it like this: all dusty.
Perhaps the most famous star cluster on the sky, the bright stars of the
Pleiades
can be seen without binoculars from even the depths of a
light-polluted city.
With a long exposure from a dark location, though, the dust cloud surrounding the
Pleiades star
cluster becomes very evident.
The above exposure took about 30 hours and covers a sky area several times the size of the full moon.
Also known as the Seven Sisters and
M45,
the Pleiades lies about 400 light years away toward the constellation of the Bull
(Taurus).
A common legend with a
modern twist is that one of the brighter stars faded since the cluster was named, leaving only six stars visible to the unaided eye.
The actual number of
Pleiades stars visible, however, may be more or less than seven, depending on the
darkness of the surrounding sky and the
clarity of the observer's eyesight.
APOD: 2011 August 3 - The Leo Triplet Galaxies from VST
Explanation:
This popular group is famous as the
Leo Triplet
- a gathering of three magnificent galaxies in one field of view.
Crowd pleasers when imaged with even modest
telescopes, these galaxies can be introduced individually as
NGC 3628 (left),
M66 (bottom right), and M65 (top right).
All three are large
spiral galaxies.
They tend to look dissimilar because their
galactic disks are
tilted at different angles to our line of sight.
NGC 3628 is seen
edge-on,
with obscuring dust lanes
cutting across the plane of the galaxy, while the disks
of M66 and
M65 are
both inclined enough to show off their spiral structure.
Gravitational interactions between galaxies in the group
have also left
telltale signs, including the
warped and inflated
disk of NGC 3628 and the drawn out spiral arms of
M66.
This gorgeous
deep view of the region was taken by the new
VLT Survey Telescope (VST) and spans about one degree
(two full moons) on the sky.
The field covers over 500 thousand
light-years at the
trio's estimated distance of 30 million light-years.
APOD: 2011 March 2 - NGC 1499: The California Nebula
Explanation:
What's California doing in space?
Drifting through the Orion Arm of the spiral Milky Way Galaxy,
this
cosmic cloud
by chance echoes the outline of
California
on the west coast of the
United States.
Our own Sun also lies within the Milky Way's
Orion
Arm, only about 1,500 light-years from the
California Nebula.
Also known as NGC 1499, the classic emission nebula is around 100
light-years long.
On many images, the most prominent glow of the California Nebula is
the red light characteristic of
hydrogen
atoms recombining with long
lost electrons, stripped away (ionized)
by energetic starlight.
In the
above image, however, hydrogen is colored green, while sulfur is
mapped to red and
oxygen mapped to blue.
The star most likely providing the energetic
starlight that ionizes much of the nebular gas is the bright, hot, bluish
Xi Persei,
just outside the right image edge.
A regular target for astrophotographers,
the California Nebula
can be spotted
with a wide-field telescope under a dark sky
toward the constellation of
Perseus, not far from the
Pleiades.
APOD: 2011 February 26 - Shell Galaxies in Pisces
Explanation:
This colorful cosmic skyscape
features a peculiar system
of galaxies cataloged as Arp 227 some 100 million light-years
distant.
Swimming
within
the boundaries of the
constellation Pisces,
Arp 227 consists of the two galaxies
prominent on the left;
the curious shell galaxy NGC 474 and its blue,
spiral-armed neighbor NGC 470.
The faint, wide arcs or
shells
of NGC 474 could have been formed by a
gravitational encounter with neighbor NGC 470.
Alternately the shells could be
caused by a merger with a
smaller galaxy producing an effect analogous to ripples across
the surface of a pond.
Remarkably, the large galaxy on the right hand side of the deep image,
NGC 467, appears to be surrounded by faint shells too,
evidence of another
interacting
galaxy system.
Intriguing background galaxies are scattered around
the field that also includes
spiky foreground stars.
Of course, those stars lie well within our own
Milky Way Galaxy.
The field of view spans 25 arc minutes or about 1/2 degree
on the sky.
APOD: 2011 February 11 - Star Colors in Orion
Explanation:
What determines
a star's color?
Its temperature.
Red stars are cool, with surface temperatures of around 3,000
kelvins (K),
while blue stars are hotter and can have temperatures over 30,000 K.
Our own lovely "yellow" Sun's temperature is a
comforting 6,000 K.
Differences in star colors are particularly easy to see
in this intriguing composite view of
the constellation Orion, made while experimenting with a star trail
step-focus technique.
In it, a series of 35 consecutive exposures were combined to produce
trails of stars moving left to right through
the frame, while changing focus in steps.
Beginning and ending with the camera out of focus
produced a sharply focused exposure near the middle of
the series and blurs the star trails into a bow tie shape.
For the brighter stars, blurring produces more saturated colors
in the images.
At the upper left, Orion's cool red
supergiant Betelgeuse
stands out from the other, hotter, bluish stars composing
the body of the constellation.
Not a star at all, the
Orion Nebula contributes a
pinkish tint below center.
Also remarkable in the field, the fainter step focus
trail of cool, deep red carbon star
W Orionis
is near the center right edge, its red hue enhanced by a
carbon-rich composition.
APOD: 2010 October 24 - A Bucket Wheel Excavator on Earth
Explanation:
Please wait while one of the largest mobile machines in the world crosses the road.
The machine pictured above is a
bucket-wheel excavator used in modern
surface mining.
Machines like this have given humanity the ability to mine minerals and
change
the face of planet Earth in new and dramatic ways.
Some open pit mines, for example, are visible from orbit.
The largest excavators
are over 200 meters long and 100 meters high, now dwarfing the
huge NASA Crawler that
transports space shuttles to the launch pads.
Bucket-wheel excavators can dig a hole the length of a football field to
over 25 meters deep in a single day.
They
may take a while to cross a road, though,
with a top speed under one kilometer per hour.
APOD: 2010 October 7 - Pacman and Hartley
Explanation:
Touring
the solar system with a 6 year
orbital period, small
comet Hartley 2
(103/P Hartley) will make its closest approach to
planet Earth on October 20 and its closest approach to
the Sun on October 28.
It may become a naked-eye comet, just visible in clear, dark skies.
Meanwhile the comet has been a tempting telescopic target,
seen here with
an alluring green coma as it shares the frame with emission
nebula NGC 281 and stars of
the constellation Cassiopeia on October 2.
The nebula's gaping profile defined by dust clouds against the red
glow suggests its more
playful moniker,
the Pacman Nebula.
An apparent short bright streak shows the comet's motion against the
background stars during the hour of accumulated exposure time.
Over the next few days Comet Hartley 2's motion will also
carry it across
a field of view featuring the famous
double star cluster in Perseus.
On November 4
a spacecraft from planet Earth will
actually fly within about 700 kilometers of
the comet's nucleus.
Now dubbed EPOXI,
that spacecraft was formerly known
as Deep Impact.
APOD: 2010 April 21 - Wide Angle: The Cat's Paw Nebula
Explanation:
Nebulae are perhaps as famous for being identified with familiar shapes as perhaps
cats are for getting into
trouble.
Still, no known
cat
could have created the vast
Cat's Paw Nebula visible in Scorpius.
At 5,500 light years distant, Cat's
Paw is an
emission nebula with a red color that originates from an abundance of ionized
hydrogen atoms.
Alternatively known as the
Bear Claw Nebula or
NGC 6334,
stars nearly ten times the mass of our
Sun have been born
there
in only the past few million years.
Pictured above,
a wide angle, deep field image of the
Cat's Paw
nebula was culled from the second
Digitized Sky Survey.
APOD: 2010 March 5 - Deep Auriga
Explanation:
The plane of our Milky Way Galaxy runs right
through
Auriga, the Charioteer.
A good part of the ancient northern constellation's
rich collection of nebulae and star clusters is featured in
this expansive, 10 degree wide skyscape.
Bright star
Elnath
lies near the bottom right,
linking Auriga to another constellation, Taurus, the Bull.
Three open star clusters, Charles Messier's
M36,
M37, and
M38 line up in the
dense star field above and left of Elnath, familiar to many
binocular-equipped skygazers.
But the deep exposure also brings out the reddish emission nebulae
of star-forming regions
IC 405,
IC 410, and
IC 417.
E. E. Barnard's dark nebulae B34 and B226
just stand out against a brighter background.
For help identifying even more of Auriga's deep sky highlights,
put your cursor over the image.
APOD: 2010 February 14 - Field of Rosette
Explanation:
What surrounds the florid Rosette nebula?
To better picture this area of the sky, the
famous flowery
emission nebula
on the far right has been captured recently in a deep and
dramatic wide field image that features several other sky highlights.
Designated NGC 2237, the center of the
Rosette nebula is populated by the bright blue stars of
open cluster NGC 2244, whose
winds
and energetic light are evacuating the nebula's center.
Below the famous flower, a symbol of
Valentine's Day, is a
column of dust and gas that appears like a rose's stem but extends hundreds of light years.
Across the
above image, the bright blue star just left and below the center is called
S Monocerotis.
The star is part of the open cluster
of stars labelled NGC 2264 and known as the
Snowflake cluster.
To the right of S Mon is a dark pointy featured called the
Cone nebula, a nebula likely shaped by winds flowing out a massive star obscured by dust.
To the left of S Mon is the
Fox Fur nebula, a tumultuous region created by the rapidly evolving Snowflake cluster.
The Rosette region, at about 5,000
light years distant, is about twice as far away as the region surrounding S Mon.
The entire field
can be seen with a small telescope toward the
constellation of the
Unicorn
(Monoceros).
APOD: 2010 January 21 - Dust and the NGC 7771 Group
Explanation:
Galaxies of the NGC 7771 Group are featured in
this intriguing skyscape.
Some 200 million light-years distant toward the constellation
Pegasus,
NGC 7771 is the large, edge-on
spiral near center,
about 75,000 light-years across, with two smaller galaxies just
below it.
Large spiral NGC 7769 is seen face-on to the right.
Galaxies of the NGC 7771 group are interacting, making
repeated close passages that will ultimately result in
galaxy-galaxy mergers on a cosmic timescale.
The interactions can be traced by galaxy
distortions and faint
streams of stars
created by gravitational tides.
But a clear view of the galaxy group is difficult to come by,
as the deep image also reveals extensive clouds of
foreground dust sweeping across the field.
The dim, dusty nebulae reflect starlight from our own Milky Way Galaxy
and lie only a few hundred light-years above the
galactic plane.
APOD: 2009 December 9 - HUDF Infrared: Dawn of the Galaxies
Explanation:
When did galaxies form?
To help find out, the deepest
near-infrared image of the sky ever has been taken of the
same field
as the optical-light
Hubble Ultra Deep Field (HUDF) in 2004.
The new image was taken this summer by the newly installed
Wide Field Camera 3 on the
refurbished Hubble Space Telescope.
Faint red smudges identified on the
above image likely surpass
redshift 8 in distance.
These galaxies
therefore likely existed when the
universe was only a few percent of its
present age,
and may well be members of the
first class of galaxies.
Some large modern
galaxies
make a colorful foreground to the distant galaxies.
Analyses by the
HUDF09 team
indicate that at least some of these
early galaxies
had very little interstellar dust.
This early class
of low luminosity galaxies likely contained
energetic stars emitting light that
transformed much of the remaining
normal matter in the universe from a cold gas to a hot
ionized plasma.
APOD: 2009 November 26 - M78 Wide Field
Explanation:
Interstellar
dust clouds and glowing nebulae abound in the fertile
constellation of Orion.
One of the
brightest,
M78, is centered in this colorful,
wide field view, covering an area
north of Orion's belt.
At a distance of about 1,500 light-years, the
bluish reflection nebula is
around 5 light-years across.
Its tint is due to dust
preferentially
reflecting the blue light
of hot, young stars.
Reflection nebula NGC 2071 is just to the left of M78.
To the right of M78 and much more compact in appearance,
the intriguing McNeil's Nebula is a recently
recognized variable nebula
associated with
the formation of a sun-like star.
The remarkably deep exposure also brings out the region's faint but
pervasive reddish glow of atomic hydrogen gas.
APOD: 2009 November 8 - M7: Open Star Cluster in Scorpius
Explanation:
M7 is one of the most prominent
open clusters
of stars on the sky.
The cluster, dominated by bright blue
stars,
can be seen with the naked eye in a dark sky
in the tail of the constellation of the Scorpion (Scorpius).
M7 contains about 100 stars in total, is about
200 million years old,
spans 25
light-years across, and lies about 1000 light-years away.
The above deep exposure was taken last month over several nights from
Yalbraith,
NSW,
Australia.
The M7 star cluster
has been known since ancient times, being noted by
Ptolemy in the year
130 AD.
Also visible are a
dark dust cloud
and literally millions of unrelated stars
towards the Galactic center.
APOD: 2009 November 6 - Ring Nebula Deep Field
Explanation:
A familiar sight to sky enthusiasts with even a small telescope,
the Ring
Nebula (M57) is
some 2,000 light-years away in the musical
constellation
Lyra.
The central ring is about one light-year across,
but this remarkably deep exposure -
a collaborative effort combining data from three different telescopes -
explores
the looping filaments
of glowing gas extending much farther from the nebula's
central star.
Of course, in this
well-studied
example of a
planetary nebula,
the glowing material does not come from planets.
Instead,
the gaseous shroud represents outer layers
expelled from a dying, sun-like star.
This remarkable composite image includes narrowband image data
recording the Ring's atomic hydrogen emission (shown as violet)
in visible light and molecular hydrogen emission (shown as red)
at near infrared wavelengths.
The much more distant spiral
galaxy IC 1296 is also visible at the upper right.
APOD: 2009 November 3 - Seven Sisters Versus California
Explanation:
On the upper right, dressed in blue, is the
Pleiades.
Also known as the
Seven
Sisters and
M45,
the Pleiades
is one of the brightest and
most easily visible
open clusters
on the sky.
The Pleiades
contains over 3,000 stars, is about 400 light years away, and only 13 light
years across.
Surrounding the stars is a spectacular blue
reflection nebula made of fine
dust.
A
common legend is that one of the brighter stars
faded since the cluster was named.
On the lower left, shining in red, is the
California Nebula.
Named for its shape, the
California
Nebula is much dimmer and hence harder to see
than the Pleiades.
Also known as NGC 1499, this mass of red glowing
hydrogen gas is about 1,500 light years away.
Although about 25 full moons could fit
between them, the above wide angle, deep field image composite has captured
them
both.
APOD: 2009 October 14 - Pleiades and Stardust
Explanation:
Have you ever seen the Pleiades star cluster?
Perhaps the most famous star cluster on the sky, the
Pleiades
can be seen without binoculars from even the depths of a
light-polluted city.
Also known as the Seven Sisters and
M45,
the Pleiades is one of the
brightest and closest open clusters.
Hurtling through a cosmic dust cloud a mere 400 light-years away,
the Pleiades
or Seven Sisters
star cluster is well-known for its striking blue
reflection nebulae.
This remarkable wide-field (3 degree)
image of the region
shows the famous
star cluster near the center, while
highlighting lesser known dusty
reflection nebulas
nearby, across an area that would
span
over 20
light-years.
In this case, the sister stars and
cosmic dust clouds
are not related, they just happen to be passing through
the same region of space.
APOD: 2009 August 26 - Classic Orion Nebulae
Explanation:
The Great Nebula
in Orion, also known as M42, is one of the
most famous nebulae in the sky.
The star forming region's glowing gas clouds and hot young stars
are near the center of this colorful
deep
sky image that includes the smaller
nebula M43
and dusty, bluish reflection nebulae
NGC 1977 and friends on the left.
Located at the edge of an otherwise invisible giant molecular
cloud
complex, these eye-catching nebulae represent only a small
fraction of this galactic neighborhood's wealth of
interstellar
material.
Captured with very modest equipment, the gorgeous skyscape was
awarded Best in Show at the
2009
Starfest International Salon of Astrophotography.
Judges commented that the detail and shading were exquisite
in this version of a classic astronomical image.
The field spans nearly 3 degrees or about 75 light-years
at the Orion Nebula's estimated distance of 1,500 light-years.
APOD: 2009 July 1 - Three Galaxies in Draco
Explanation:
This intriguing trio of galaxies is sometimes
called the Draco Group, located in the northern
constellation of (you guessed it)
Draco.
From left to right are
edge-on spiral NGC 5981,
elliptical galaxy NGC 5982, and
face-on spiral NGC 5985 --
all within this single telescopic
field of view spanning a little more than
half the width of the full moon.
While the group is far too small to be a
galaxy cluster
and has not been
cataloged
compact group, these galaxies all do lie roughly
100 million light-years from planet Earth.
On close examination with spectrographs, the bright core of the
striking face-on spiral NGC 5985 shows
prominent emission in specific wavelengths of light, prompting
astronomers to classify it as a
Seyfert, a type of active galaxy.
Not as well known as other tight
groupings of galaxies,
the contrast in visual appearance
makes this triplet an attractive subject for
astrophotographers.
This impressively
deep exposure of the region also reveals faint
and even more distant
background galaxies.
APOD: 2009 May 26 - Whirlpool Galaxy Deep Field
Explanation:
Follow the handle of
the
Big Dipper away from the dipper's bowl, until
you get to the handle's last bright star.
Then, just slide your telescope a little
south and west and
you might find this
stunning pair of interacting galaxies,
the 51st entry
in Charles
Messier's famous
catalog.
Perhaps the original
spiral nebula, the large galaxy with
well defined spiral structure is also cataloged as
NGC 5194.
Its spiral arms and dust lanes
clearly sweep in front of its companion galaxy (left),
NGC 5195.
The pair are
about 31 million light-years distant and
officially lie within the angular boundaries of the small constellation
Canes Venatici.
Though M51
looks faint and fuzzy to the human eye,
the above long-exposure, deep-field image taken last month shows much of the faint complexity that actually surrounds the smaller galaxy.
APOD: 2009 May 22 - East of Antares
Explanation:
East of Antares,
dark markings sprawl through crowded
star fields toward the center
of our Milky Way Galaxy.
Cataloged in the early 20th
century by astronomer
E. E. Barnard, the obscuring
interstellar dust clouds
include
B59, B72, B77 and B78, seen in silhouette
against the starry background.
Here, their combined shape suggests
a pipe
stem and bowl,
and so the dark nebula's popular name is the Pipe Nebula.
The deep and expansive view was recorded in
very dark Chilean skies.
It covers a full 10 by 7 degree field in the
pronounceable
constellation Ophiuchus.
The Pipe Nebula is part of the Ophiuchus dark cloud complex
located at a distance of about 450 light-years.
Dense cores
of gas and dust within the Pipe Nebula are collapsing to form stars.
APOD: 2009 April 25 - Dark Markings of the Sky
Explanation:
Based on wide field photographs, American astronomer
Edward Emerson Barnard cataloged the
dark markings of the sky in the
early 20th century.
Barnard's markings are dark nebulae,
interstellar clouds of obscuring gas and dust.
Their shapes are visible in
cosmic silhouette because they
lie in the foreground along the line-of-sight to rich star fields
and stellar nurseries near the plane of our Galaxy.
This deep
telescopic image from the early 21st century captures a
tantalizing array of Barnard's dusty nebulae toward the
constellation Taurus and the Taurus molecular cloud
some 400 light-years away.
Included in
the nearly 1 degree wide field of view is Barnard 7
(the 7th object in the catalog) at the upper right, next to
a dusty bluish reflection nebula.
Young variable star
RY Tauri is emerging from a
yellowish cocoon of dust near top center.
Typically a light-year or so across, many of Barnard's
dark nebulae
are themselves likely sites of future star formation.
APOD: 2009 March 10 - Horsehead and Orion Nebulae
Explanation:
Adrift 1,500 light-years away in one of
the night sky's
most recognizable
constellations, the glowing
Orion Nebula and the dark
Horsehead Nebula are contrasting
cosmic vistas.
They appear in opposite corners of this
stunning mosaic taken with a digital camera attached to a small telescope.
The magnificent emission region, the
Orion Nebula (aka M42), lies at the upper right of the picture.
Immediately to its left is a prominent bluish
reflection nebula sometimes called
the Running Man.
The Horsehead
nebula appears as a dark cloud, a small silhouette
notched against the long red glow at the lower left.
Alnitak is the easternmost star in
Orion's belt and is seen as the
brightest star to the left of the
Horsehead.
Below Alnitak is the
Flame Nebula, with clouds of
bright emission and dramatic dark dust lanes.
Pervasive tendrils
of glowing hydrogen gas are easily
traced
throughout the region in
this deep field image of the same region.
APOD: 2009 February 28 - NGC 2442: Galaxy in Volans
Explanation:
Distorted
galaxy NGC 2442
can be found in the southern constellation of the
flying fish,
(Piscis) Volans.
Located about 50 million light-years away, the galaxy's two
spiral
arms extending from a pronounced central bar give it a
hook-shaped appearance.
This deep color image also shows the arms' obscuring
dust lanes, young blue star clusters and
reddish star forming regions
surrounding a core of yellowish light from an older population of stars.
But the star forming regions seem more concentrated along
the drawn-out (right side)
spiral
arm.
The distorted structure is likely the result of an ancient
close encounter
with the smaller galaxy seen near the top left of this
field of view.
The two interacting galaxies are separated by about
150,000 light-years at the estimated distance
of NGC 2442.
APOD: 2008 December 27 - Crab Pulsar Wind Nebula
Explanation:
The Crab Pulsar, a city-sized, magnetized
neutron star spinning 30 times a second,
lies at the center of
this
remarkable image from
the orbiting Chandra Observatory.
The deep x-ray image gives the first
clear view of
the convoluted boundaries of the Crab's pulsar wind nebula.
Like a
cosmic
dynamo the pulsar powers the x-ray
emission.
The pulsar's energy accelerates
charged particles, producing eerie, glowing x-ray jets directed
away from the poles and an intense wind in the equatorial direction.
Intriguing edges are created as the charged
particles stream away, eventually losing energy as they interact
with the pulsar's strong magnetic field.
With more mass than the Sun and the density of an
atomic nucleus,
the spinning pulsar itself is the collapsed core of a
massive star.
The stellar core collapse resulted in a supernova explosion that
was witnessed in
the year
1054.
This Chandra image spans just under 9 light-years at the Crab's
estimated distance of 6,000 light-years.
APOD: 2008 September 3 - 31 Million Miles from Planet Earth
Explanation:
On July 4th, 2005, the Deep
Impact spacecraft directed a probe to impact the
nucleus of Comet Tempel 1.
Still cruising through the solar system, earlier this year
the robotic
spacecraft looked back to record a series of
images of its home world
31 million miles (50 million kilometers) away.
In a sequence from top left to bottom right, these four frames from
the video
show a rotating Earth.
They combine visible and near-infrared
image data with enough resolution and contrast to see
clouds, oceans, and continents.
They also follow a remarkable transit of Earth by its
large, natural satellite, the Moon.
The Moon's orbital motion carries it across the field of
view from left to right.
Imaging the Earth
from this distant perspective allows
astronomers to connect overall variations in brightness at
different wavelengths with planetary features.
The observations will aid in
the search for earthlike planets in
other planetary
systems.
APOD: 2008 April 9 - A Large Magellanic Cloud Deep Field
Explanation:
Is this a spiral galaxy?
No. Actually, it is the
Large Magellanic Cloud (LMC), the largest
satellite galaxy of our own
Milky Way Galaxy.
The LMC is
classified as a
dwarf irregular galaxy because of its normally chaotic appearance.
In this deep and wide exposure, however, the full extent of the
LMC becomes visible.
Surprisingly, during longer exposures, the
LMC begins to resemble a
barred spiral galaxy.
The
Large Magellanic Cloud lies only about 180,000
light-years
distant towards the constellation of
Dorado.
Spanning about 15,000 light-years, the LMC was the site of
SN1987A,
the brightest and closest
supernova
in modern times.
Together with the
Small Magellanic Cloud (SMC), the LMC can
be seen in Earth's southern hemisphere with the unaided eye.
APOD: 2008 April 6 - Wisps Surrounding the Horsehead Nebula
Explanation:
The famous Horsehead Nebula in Orion is not alone.
A deep exposure shows that the
dark familiar shaped indentation,
visible just below center, is part of a
vast complex of absorbing
dust and
glowing gas.
To bring out details of the
Horsehead's pasture, amateur astronomers at the
Star Shadow Remote Observatory in
New Mexico,
USA
fixed a
small telescope on the region for over seven hours filtering out all but a
very specific color of
red light emitted by
hydrogen.
They then added the image to a full color frame taken over three hours.
The resulting
spectacular picture details an intricate tapestry of gaseous wisps and dust-laden filaments that were created and sculpted over eons by
stellar winds and
ancient supernovas.
The Horsehead Nebula lies 1,500
light years
distant towards the
constellation of
Orion.
Two stars from the Orion's Belt
can be found in the
above image.
APOD: 2008 January 11 - Polaris Dust Nebula
Explanation:
Centered on North Star
Polaris,
this 4 degree wide
field of
view covers part of a complex of
relatively
unfamiliar, diffuse dust clouds
soaring high
above the plane of our Milky Way Galaxy.
The combined light of the
Milky Way stars are reflected by the dusty,
galactic cirrus,
the reflected starlight having the same blue tint
characteristic of better known
reflection nebulae.
But this deep color image also records a faint reddish
luminescence from the dust grains as they
convert invisible stellar ultraviolet radiation to
visible red light.
Dubbed
extended red emission,
the dim
cosmic glow
is thought to be caused by complex organic molecules
known as PAHs
(polycyclic aromatic hydrocarbons), common
constituents of
interstellar dust.
On planet Earth, PAHs are widely encountered as the sooty
products of combustion.
APOD: 2007 November 9 - Skyscape with Comet Holmes
Explanation:
This gorgeous skyscape spans some 10 degrees across the
heroic constellation
Perseus, about the size of a generous binocular
field of view.
The deep exposure includes bright stars,
emission nebulae,
star clusters, and, of course, the
famous Comet Holmes.
To identify the celestial landmarks,
just place your cursor over the image.
The brightest star in view, Alpha Persei, is itself
surrounded by a loose cluster of stars - the
Alpha Per
Moving Cluster -
at a distance of about 600 light-years.
But, at a distance of a mere 14
light-minutes bright
Comet
Holmes still dominates the scene with its
fluorescing greenish coma
and foreshortened blue tail.
APOD: 2007 September 10 - Building Galaxies in the Early Universe
Explanation:
What was the very early universe like?
To help find out, astronomers pointed the
Hubble Space Telescope
between bright nearby objects to create one of the deepest images ever -- the
Hubble Ultra Deep Field (HUDF).
The resulting HUDF is like a
jewel box of strange and distant galaxies.
A recent analysis of the
HUDF
focused on the smallest, faintest and most compact galaxies imaged.
These small galaxies are thought to be the
building blocks of
modern galaxies.
Analysis shows that these small galaxies are indeed themselves frequently merging to form large galaxies.
An image of this field with the
Spitzer Space Telescope
shows a lack of
infrared
emission that would be expected from old stars,
indicating that these small galaxies are very young, possibly only a few million years old.
Therefore the young blue stars might be members of the
first-ever generation of stars.
Part of the HUDF is
shown above,
while one blue building-block galaxy, highly
redshifted by the universe so as to appear more yellow,
is shown in the upper left inset.
APOD: 2007 August 4 - Sagittarius Triplet
APOD: 2007 May 28 - A Hole in Mars
APOD: 2007 January 6 - The Orion Deep Field
APOD: 2006 November 22 - A Bucket Wheel Excavator on Earth
APOD: 2006 November 20 - M42: Wisps of the Orion Nebula
APOD: 2006 October 15 - An Orion Deep Field
APOD: 2006 June 28 - The Cat's Paw Nebula
APOD: 2006 June 14 - Sagittarius Triplet
APOD: 2006 May 6 - Three Galaxies in Draco
APOD: 2006 March 9 - Trio Leo
APOD: 2005 October 25 - Supernova Remnant N132D in Optical and X Rays
APOD: 2005 May 12 - Stars, Galaxies, and Comet Tempel 1
APOD: 2004 September 29 - HUDF: Dawn of the Galaxies
APOD: 2004 March 9 - The Hubble Ultra Deep Field
APOD: 2004 January 15 - An Orion Deep Field
APOD: 2003 December 17 - A Proton Aurora
APOD: 2003 November 20 - Voyager at 90 AU
APOD: 2003 September 26 - IC1340 in the Eastern Veil
APOD: 2003 July 20 - An Ion Drive for Deep Space 1
APOD: 2003 June 25 - Galaxies in the GOODS
APOD: 2003 May 19 - The Andromeda Deep Field
APOD: 2002 October 12 - Chandra Deep Field
APOD: 2002 September 1 - The Hubble Deep Field
APOD: 2002 June 29 - A Deep Field In The Southern Sky
APOD: 2002 March 6 - Simulated Galaxy Cluster View
APOD: 2002 January 17 - Pick a Galaxy Any Galaxy
APOD: 2001 November 13 - A Gravity Map of Earth
APOD: 2001 October 29 - Spinning Black Holes and MCG 6 30 15
APOD: 2001 September 22 - Full Throttle For Deep Space 1
APOD: 2001 April 4 - Distant Supernova, Dark Energy
APOD: 2001 March 28 - Chandra Deep Field
APOD: 2001 February 8 - Distant Galaxies in Radio Vision
APOD: 2000 August 31 - Full Throttle For Deep Space 1
APOD: 2000 July 9 - The Hubble Deep Field
APOD: December 14, 1998 - The Hubble Deep Field South
APOD: December 2, 1998 - A Deep Field In The Southern Sky
APOD: October 26, 1998 - An Ion Drive for Deep Space 1
APOD: October 12, 1998 - The Hubble Deep Field in Infrared
APOD: September 15, 1998 - The NTT SUSI Deep Field
APOD: June 7, 1998 - The Hubble Deep Field
APOD: June 25, 1997 - A GRB Host?
APOD: February 9, 1997 - The Deep Field
APOD: June 28, 1996 - A Distant Galaxy in the Deep Field
APOD: January 24, 1996 - The Deep Field
Explanation:
These three bright nebulae are often
featured in telescopic tours of the constellation
Sagittarius and the crowded starfields of
the central Milky Way.
In fact, 18th century cosmic tourist
Charles Messier
cataloged two of them; M8, the nebula below and right of center,
and colorful M20 at the upper right.
The third, NGC 6559, is left of M8,
separated from the the larger nebula by a dark dust lane.
All three are stellar nurseries about
five thousand light-years or so distant.
The expansive M8, over a hundred light-years across,
is also known as the Lagoon Nebula while M20's popular moniker is
the Trifid.
This stunning digital view is actually a collaborative
composite recorded by 2 cameras and 2 telescopes
about 2 thousand miles apart.
The deep, wide image field was captured under dark
Arizona
skies.
Both M8 and M20 were recorded in more detail from
an
observatory in Pennsylvania.
Glowing hydrogen gas creates the dominant red color of the
emission nebulae, with contrasting blue hues, most striking in the
Trifid, due to dust reflected starlight.
Explanation:
Black spots have been discovered on Mars that are so dark that nothing inside can be seen.
Quite possibly,
the spots
are entrances to deep
underground caves capable of protecting
Martian life, were it to exist.
The unusual hole pictured above was found on the slopes of the giant Martian volcano
Arsia Mons.
The above image was captured three weeks ago by the
HiRISE instrument onboard the
Mars Reconnaissance Orbiter
currently circling Mars.
The holes were originally identified on lower resolution images from the
Mars Odyssey spacecraft,
The above hole is about the size of a
football field
and is so deep that it is completely
unilluminated by the Sun.
Such holes and
underground caves
might be prime targets for
future spacecraft,
robots, and even the next generation of
human interplanetary explorers.
Explanation:
Adrift 1,500 light-years away in one of
the night sky's most recognizable
constellations, the glowing
Orion Nebula and the dark
Horsehead Nebula are contrasting
cosmic vistas.
But even fainter filaments of glowing gas are easily traced
throughout the region in
this
stunning composite image
that includes exposures filtered to record emission
from hydrogen atoms.
The view reveals extensive
nebulosities associated with
the giant Orion Molecular
Cloud
complex, itself hundreds of light-years across.
A magnificent emission region, the
Orion
Nebula (aka M42) lies at the
upper right of the picture.
Immediately to its left are a cluster of prominent bluish
reflection nebulae sometimes called
the Running Man.
The Horsehead
nebula appears as a dark cloud, a small silhouette
notched against the long red glow left of center.
Alnitak is the easternmost star in Orion's belt and
the brightest star to the left of the Horsehead.
Below Alnitak is the
Flame Nebula, with clouds of
bright emission and dramatic dark dust lanes.
Completing the trio of Orion's belt
stars, bluish Alnilam and Mintaka form a line with Alnitak,
extending to the upper left.
Explanation:
Please wait while one of the largest mobile machines in the world crosses the road.
The machine pictured above is a
bucket-wheel excavator used in modern
surface mining.
Machines like this have given humanity the ability to mine minerals and
change
the face of planet Earth in new and dramatic ways.
Some open pit mines, for example, are visible from orbit.
The largest excavators
are over 200 meters long and 100 meters high, now dwarfing the
huge NASA Crawler that
transports space shuttles to the launch pads.
Bucket-wheel excavators can dig a hole the length of a football field to
over 25 meters deep in a single day.
They may take a while to cross a road, though,
with a top speed under one kilometer per hour.
Explanation:
The Great Nebula in Orion, an immense, nearby
starbirth region,
is probably the most famous of all
astronomical nebulas.
Here, glowing gas surrounds hot young stars at the edge of an
immense interstellar
molecular cloud only 1500
light-years away.
In the above deep image, faint wisps and sheets of
dust and gas are particularly evident.
The Great Nebula in Orion can be found with the
unaided eye just below and to the left of the
easily identifiable
belt of three stars in the popular constellation Orion.
In addition to housing a bright
open cluster of stars known as the
Trapezium, the
Orion Nebula contains many
stellar nurseries.
These nurseries contain
hydrogen gas, hot young stars,
proplyds, and
stellar jets
spewing material at high speeds.
Also known as
M42, the
Orion Nebula spans about 40 light years and is located in the same
spiral arm of
our Galaxy as the
Sun.
Explanation:
Adrift 1,500 light-years away in one of
the night sky's
most recognizable
constellations, the glowing
Orion Nebula and the dark
Horsehead Nebula are contrasting
cosmic vistas.
They both appear in this stunning composite digital image
assembled from over 20 hours of data that includes exposures
filtered to record emission from hydrogen
atoms.
The view reveals extensive
nebulosities associated with
the giant Orion Molecular
Cloud
complex, itself hundreds of light-years across.
The magnificent emission region, the
Orion
Nebula (aka M42), lies at the
upper right of the picture.
Immediately to its left are a cluster of
of prominent bluish
reflection nebulae sometimes called
the Running Man.
The Horsehead
nebula appears as a dark cloud, a small silhouette
notched against the long red glow at the lower left.
Alnitak is the easternmost star in Orion's belt and
is seen as the brightest star to the left of the Horsehead.
Below Alnitak is the
Flame Nebula, with clouds of
bright emission and dramatic dark dust lanes.
Fainter tendrils of glowing hydrogen gas are easily traced
throughout the region in
this
Orion deep field.
Explanation:
Nebulae are perhaps as famous for being identified with
familiar shapes as cats are for getting into trouble.
Still, no known cat could have created the vast
Cat's Paw Nebula visible in Scorpius.
At 5,500 light years distant, Cat's
Paw is an
emission nebula with a red color that
originates from an abundance of ionized
hydrogen atoms.
Alternatively known as the
Bear Claw Nebula or
NGC 6334, stars nearly ten times the mass of our
Sun have been born
there in only the past few million years.
This
deep wide-field image of the Cat's Paw nebula
was photographed from
New South Wales,
Australia.
Explanation:
These three bright nebulae are often
featured in telescopic tours of the constellation
Sagittarius and the crowded starfields of
the central Milky Way.
In fact, 18th century cosmic tourist
Charles Messier
cataloged two of them; M8, the nebula below and right of center,
and colorful M20 at the upper right.
The third, NGC 6559, is left of M8,
separated from the the larger nebula by a dark dust lane.
All three are stellar nurseries about
five thousand light-years or so distant.
The expansive M8, over a hundred light-years across,
is also known as the Lagoon Nebula while M20's popular moniker is
the Trifid.
This stunning digital view is actually a collaborative
composite recorded by 2 cameras and 2 telescopes
about 2 thousand miles apart.
The deep, wide image field was captured under dark
Arizona
skies.
Both M8 and M20 were recorded in more detail from
an
observatory in Pennsylvania.
Glowing hydrogen gas creates the dominant red color of the
emission nebulae, with contrasting blue hues, most striking in the
Trifid, due to dust reflected starlight.
Explanation:
This intriguing trio of galaxies is sometimes
called the NGC 5985/Draco Group
and so (quite reasonably) is located in the northern
constellation
Draco.
From left to right are
face-on spiral NGC 5985,
elliptical galaxy NGC 5982, and
edge-on spiral NGC 5981 --
all within this single telescopic
field of view spanning a little more than
half the width of the full moon.
While this grouping is far too small to be a
galaxy cluster
and has not been
cataloged
as a compact group,
these galaxies all do lie roughly
100 million light-years from planet Earth.
On close examination with spectrographs, the bright core of the
striking face-on spiral NGC 5985 shows
prominent emission in specific wavelengths of light, prompting
astronomers to classify it as a
Seyfert, a type of active galaxy.
Not as well known as other tight
groupings of galaxies,
the contrast in visual appearance
makes this triplet an attractive subject for
astrophotographers.
This impressively deep exposure of region also reveals faint
and even more distant
background galaxies.
Explanation:
This popular group is famous as the
Leo
Triplet - a gathering of three magnificent galaxies
in one field of view.
Crowd pleasers when imaged with even modest
telescopes, these galaxies can be introduced individually as
NGC 3628 (top), M66 (bottom left), and M65 (bottom right).
All three are large
spiral galaxies.
They tend to look dissimilar because their galactic disks are
tilted at different angles to our line of sight.
NGC 3628 is seen
edge-on,
with obscuring dust lanes
cutting across the plane of the galaxy, while the disks
of M66 and
M65 are
both inclined enough to show off their spiral structure.
Gravitational interactions between galaxies in the group
have also left telltale signs, including the
warped and inflated
disk of NGC 3628 and the drawn out spiral arms of M66.
This gorgeous
deep view of the region spans about one degree
(two full moons) on the sky.
The field covers over 500 thousand light-years at the
trio's estimated distance of 30 million light-years.
Explanation:
Thousands of years after a star exploded, its expanding remnant
still glows brightly across the spectrum.
Such is the case with
N132D, a
supernova remnant located in the neighboring
Large Magellanic Cloud (LMC) galaxy.
The expanding shell from this explosion now spans 80
light-years
and has swept up about 600 Suns worth of mass.
N132D was imaged recently in optical light and in great detail with the
Hubble Space Telescope.
The Hubble image was then combined with a position coincident detailed image in
X-ray light taken by the
Chandra X-ray Observatory.
The combination,
shown above
in representative colors, shows a nearly spherical expanding
shockwave
highlighted by pink emission from
hydrogen
gas and purple emission from
oxygen gas.
A dense field of unrelated stars also from the
LMC populates the image.
Studying the image gives an opportunity to study material
once hidden deep inside a star.
N132D spans about 150 light years and lies about 160,000
light years away toward the
constellation of
Dorado.
Explanation:
Faint
comet
Tempel 1 sports a fuzzy blue-tinted tail,
just right of center in this
lovely field of stars.
Recorded on May 3rd slowly sweeping through the
constellation Virgo,
periodic comet Tempel 1
orbits the Sun once every 5.5 years.
Also caught in the skyview are two galaxies
at the upper left -
NGC 4762 and NGC 4754 -
both members of the large
Virgo
Cluster of galaxies.
Classified as a
lenticular
galaxy, NGC 4762
presents an edge-on disk as a narrow gash of light
while NGC 4754 is a football-shaped
elliptical galaxy.
Similar in apparent size,
the galaxies and comet make for an intriguing
visual comparison,
but Tempel 1 is only about 3 light-minutes from planet Earth.
The two Virgo cluster galaxies are 50 million
light-years away.
NASA's
Deep Impact
spacecraft is scheduled to encounter
Tempel 1 on July 4th, launching a probe to impact
the comet's nucleus.
Explanation:
When did galaxies form?
Faint red smudges identified on the
deepest optical sky image
ever taken may well be members of the first class of galaxies.
Detailed inspection of the
Hubble Ultra Deep Field (HUDF), taken by the
Advanced Camera for Surveys
on the
Hubble Space Telescope,
found the galaxies, circled above, and used their distance and abundance to
probe the universe
when it was only a few percent of its present age.
Analyses indicate that the discovered class of galaxies is exclusively composed of these smaller
dwarf galaxies from which larger
modern galaxies must have formed.
Some large modern galaxies make a colorful foreground to the above
HUDF.
The first class of dwarf galaxies likely contained
energetic stars emitting light that
transformed much of the remaining
normal matter in the universe from a cold gas to a hot
ionized plasma.
Explanation:
What did the first galaxies look like?
To help answer this question, the Hubble Space Telescope has just finished taking the Hubble Ultra Deep Field (HUDF), the deepest image of the
universe ever taken in
visible light.
Pictured above, the HUDF shows a sampling of the
oldest galaxies ever seen,
galaxies that formed just after the
dark ages, 13 billion years ago, when the universe was
only 5 percent of its present age.
The Hubble Space Telescope's
NICMOS and new
ACS cameras took the image.
Staring nearly 3 months at the same spot, the
HUDF is four times more sensitive, in some colors,
than the original Hubble Deep Field (HDF).
Astronomers the world over will likely study the
HUDF for years to come to
better understand how stars and galaxies formed in the early universe.
Explanation:
Adrift 1,500 light-years away in one of
the night sky's
most recognizable
constellations, the glowing
Orion Nebula and the dark
Horsehead Nebula are contrasting
cosmic vistas.
They both appear in this stunning composite digital image
assembled from over 20 hours of data that includes exposures
filtered to record emission from hydrogen
atoms.
The view reveals extensive
nebulosities associated with
the giant Orion Molecular
Cloud
complex, itself hundreds of light-years across.
The magnificent emission region, the
Orion
Nebula (aka M42), lies at the
upper right of the picture.
Immediately to its left are a cluster of
of prominent bluish
reflection nebulae sometimes called
the Running Man.
The Horsehead
nebula appears as a dark cloud, a small silhouette
notched against the long red glow at the lower left.
Alnitak is the easternmost star in Orion's belt and
is seen as the brightest star to the left of the Horsehead.
Below Alnitak is the
Flame Nebula, with clouds of
bright emission and dramatic dark dust lanes.
Fainter tendrils of glowing hydrogen gas are easily traced
throughout the region in
this
Orion deep field.
Explanation:
What are auroras made out of?
Triggered by solar activity,
normal auroras are caused by
collisions between fast-moving
electrons
and the oxygen and nitrogen in Earth's upper atmosphere.
The electrons come from the
magnetosphere, the region of space controlled by
Earth's magnetic field.
As the excited oxygen and nitrogen molecules
return to their low energy state, they emit light,
seen as the auroral glow.
Sometimes, however,
auroras can be caused by collisions with heavier
protons,
causing a more energetic display with strong
ultraviolet
emission.
In addition, protons can temporarily capture an electron and emit
light for themselves.
Such a proton aurora is seen above, recorded by the
IMAGE satellite.
A special feature is the bright
spot near picture center, embedded
in a ring of auroral emission around
the north magnetic pole of planet Earth.
Most solar wind protons
never reach the Earth to cause
auroras because they are completely deflected away at a
great distance by the Earth's magnetic field.
The bright spot in the
auroral ring
indicates a particularly
deep crack
in the Earth's magnetic field where
protons
were able to flow along a temporarily connected
region between the
Sun and the Earth,
relatively undeflected, until they impacted the
Earth's ionosphere.
Explanation:
Launched
in 1977, Voyager 1 is now about 12 light-hours
or 90 astronomical
units (AU)
Explanation:
These ghostly filaments of interstellar gas are just a small
part of the
expansive
Veil Nebula, seen against a rich field
of background stars in the
long-necked
constellation
Cygnus.
Also known as the
Cygnus Loop, the Veil Nebula is a
supernova remnant,
the expanding debris cloud created by a stellar
explosion whose light first reached planet Earth
from 5,000 to 10,000 years ago.
About 1,400 light-years away,
the entire nebula now appears
to span over 3 degrees on
the sky, nearly 6 times the apparent size of the full moon,
but is faint and can be difficult to see in small telescopes.
The region captured in
this
beautiful, deep, color image
is located at the southern tip of the Veil's
eastern
crescent.
It covers about 10 light-years at the distance of
the Veil and is cataloged as IC1340.
Explanation:
Space travel entered the age of the ion drive in 1998 with the launch of
Deep Space 1,
a NASA mission designed primarily to test new technologies.
Although the ion drive on
Deep Space 1 provided
acceleration
much smaller than we feel toward
Earth,
it gradually gave the spacecraft the speed it needed to travel across our
Solar System.
The propulsion drive worked by ionizing
xenon atoms with power provided by large panels that collect sunlight.
As these ions were expelled by a strong
electric field out the back, the spacecraft slowly gained speed.
Pictured above, hot blue ions emerge from a prototype drive that was
successfully tested at
JPL in 1997.
Deep Space 1
successfully zoomed past asteroid
9969 Braille in July 1999 and then
Comet Borrelly in September 2001,
then obtaining the
most detailed photograph
ever taken of a comet nucleus.
The spacecraft was retired in December 2001
Explanation:
This tantalizing view of galaxies scattered near and far is part of the
Hubble Space Telescope's
contribution
to the GOODS - the
Great Observatories Origins Deep Survey project.
The GOODS'
goal is to study
galaxy
formation and evolution over an unprecedent wide range of
cosmic
distances, therefore spanning
time from
the present to the early Universe.
Joined by the
Chandra
X-ray Observatory and soon by the anticipated
Space
Infrared Telescope Facility
along with major ground-based
observatories, the project expands greatly on the past
Hubble Deep Fields of regions in the northern constellation of
Ursa Major and southern constellation Tucana.
Across the
electromagnetic
spectrum, a sample of
large nearby galaxies,
like the interacting pair at the lower left above, will be compared with
distant younger
galaxies in a search for clues to the origins of
these lighthouses of the cosmos.
Preliminary results of the project confirm that the birth rate
of stars was higher in the past and that galaxies
have indeed been constructed from
the "bottom up", growing
from mergers and accretion of small infant galaxies to their
present day forms.
Explanation:
What can you learn from looking into the depths of space?
In an effort to find out true ages of stars in neighboring
Andromeda galaxy's
halo, astronomers stared into the
galaxy giant with the new
Advanced Camera for Surveys through the
Hubble Space Telescope.
The resulting exposure of over three days,
shown above, is the deepest exposure in visible light ever taken,
although shorter in duration than the multi-wavelength effort toward the
Hubble Deep Field.
The final image illuminated not only
Andromeda (M31) but the distant universe.
Andromeda's halo stars turned out to be have a
wider range of ages than our
Milky Way's halo stars,
likely indicating more encounters with
small neighboring galaxies.
Visible on the
above left is one of Andromeda's
globular star clusters, while literally
thousands of background galaxies are seen in the
distance universe,
far beyond M31.
Explanation:
Officially the
Chandra
Deep Field - South, this picture represents the deepest ever
x-ray image of the Universe.
One million seconds of accumulated exposure time with the orbiting
Chandra X-ray Observatory went in to its making.
Concentrating on a single, otherwise unremarkable patch
of sky in the constellation
Fornax,
this x-ray image corresponds to the
visible light Hubble Deep Field - South
released in 1998.
Chandra's view, color coded with low energies in red, medium in green,
and high-energy x-rays in blue, shows many faint sources of relatively
high-energy x-rays.
These are likely active galaxies feeding supermassive central
black holes
and large clusters of galaxies
at distances of up to 12 billion light-years.
The stunning picture supports
astronomers' ideas
of a youthful
universe in which massive black holes
were much more dominant than at present.
Explanation:
Galaxies like
colorful pieces of candy fill the
Hubble Deep Field - one of
humanity's most distant
optical views of the Universe.
The dimmest, some as faint as 30th
magnitude
(about four billion times fainter than stars visible to the unaided eye),
are very distant galaxies and represent what
the Universe looked like in the
extreme past, perhaps less than one billion years after the
Big Bang.
To make the Deep Field image, astronomers
selected an uncluttered area of the sky in the
constellation Ursa Major (the Big Bear) and
pointed the Hubble Space Telescope
at a single spot for 10 days accumulating and combining
many separate exposures. With each
additional exposure, fainter
objects were revealed.
The final result has been used to explore the
mysteries of galaxy evolution and the infant
Universe.
Explanation:
This
deep view of the cosmos is the sequel to the 1995 hit
Hubble Space Telescope Deep Field.
Billed as the Hubble Deep Field South, it was produced
by pointing the space telescope toward a patch of sky in the
southern constellation Tucana.
Over a period of 10 days, many separate exposures were accumulated
and combined to reveal progressively fainter galaxies.
The original deep field was constructed by observing a piece of sky
in the northern constellation Ursa Major.
Both stare down 12 billion light-year long tunnels
to far-off and still mysterious times when
young galaxies inhabited
an infant universe.
Hubble Deep Field South observations were released to an
enthusiastic
audience on November 23, 1998.
Explanation:
Stunningly detailed, this picture is a
computer simulated view
of a cluster of galaxies
in the distant cosmos.
A large, elliptical galaxy dominates this hypothetical cluster's
central region surrounded by a swarm of member galaxies.
Other galaxies which lie far behind the cluster are seen as numerous
visible concentric arcs -
lensed by the enormous
gravitational field
dominated by dark matter
within the cluster itself.
Such magnificent images are expected to be achieved by the
Advanced
Camera for Surveys (ACS), one of
the upgrades
being installed on the
Hubble Space Telescope during the
ongoing servicing mission.
Compared to Hubble's workhorse
Wide Field Planetary Camera 2
(WFPC2), whose achievements include the current
deep
field views of the Universe, the new technology ACS
will be twice as sharp an imager with twice the
field of view and five times the sensitivity.
Along with extended views of the distant cosmos,
enthusiastic astronomers also plan to use the ACS to monitor
our own Solar System and to search for
planets orbiting stars beyond the Sun.
Explanation:
Pick a galaxy,
any galaxy.
In the top panel you can
choose from a myriad of
distant galaxies
revealed in a deep Hubble Space Telescope image of a narrow slice of
the cosmos toward the constellation
Hercules.
If you picked the distorted reddish galaxy indicated by the yellow box,
then you've chosen one a team of infrared astronomers has recently
placed at a distance of 9 billion light-years.
Classified as an ERO (Extremely Red Object), this galaxy is
from a time
when the
Universe was only one third its
present age.
Along the bottom panel, this galaxy's
appearance
in filters ranging from visible to infrared
wavelengths
(left to right) is presented as a series of negative images.
The brightness of the galaxy in the infrared compared
to the visible suggests that light from intense star
formation activity, reddened by dust clouds within
the galaxy itself, is responsible for the extremely red color.
Astronomers estimate that this galaxy has around 100 billion stars
and may in fact be a very distant mirror -- an
analog
of our own
Milky Way
Galaxy in its
formative years.
Explanation:
Is
gravity the same over the surface of the
Earth?
No -- it turns out that in some places you will feel slightly
heavier than others.
The
above relief map shows in exaggerated highs and lows where the
gravitational field of
Earth is relatively strong and weak.
A low spot can be seen just off the coast of
India, while a relative high occurs in the South
Pacific Ocean.
The cause of these irregularities is unknown
since present surface features do not appear dominant.
Scientists
hypothesize that factors that are more important lay in deep underground structures and may be related to the
Earth's appearance in the distant past.
To better map
Earth's gravity and hence better understand its
interior and past,
NASA plans to launch the
Gravity Recovery and Climate (GRACE) satellite in February.
Explanation:
What makes the core of galaxy MCG-6-30-15 so bright?
Some
astronomers believe the answer is a massive
spinning black hole.
If so, this would be the first
observational indication that it is possible to make a
black hole act like a
battery -- and tap into its rotational energy.
MCG-6-30-15 is a distant
galaxy that has
recently been observed with the orbiting
XMM-Newton satellite in
X-ray light.
These observations show the
galaxy's nucleus not only to be
very bright but also to show evidence that
much of the light is climbing out of a deep gravitational well.
A spinning black hole could explain both effects.
A strong
magnetic field could be the
mediator transferring rotational energy from the
black hole to the surrounding gas.
Pictured above is an artist's illustration of a
black hole surrounded by an
accretion disk.
For clarity, the illustration does not include
distorting gravitational lens effects.
Explanation:
At full throttle the
Deep Space 1 spacecraft's
innovative ion drive
produces about 1/50th of a pound of thrust ... a force so great
that it would
just about
hold up a piece of paper on planet Earth!
Still, powered by solar arrays
ion propulsion
systems can run continuously.
For long duration space missions they ultimately
win out
over the powerful
but brief blasts of less efficient
chemical rockets.
Deep Space 1 is
seen
here suspended in an assembly room, a folded
solar array
resting above the circular ion propulsion module.
Already a successful
technology
demonstrator with experimental
autonomous software,
the spacecraft flew by
asteroid 9969 Braille in July of 1999.
Later that year, in November, the robot probe was
nearly lost due to the failure of its wide-field star tracker camera.
But engineers were able to reprogram the navigation
system to utilize another on-board camera and on 28 June 2000
the ion drive was throttled up.
Now, the
adventures
of Deep Space 1 continue.
Again
steering by the stars, Deep Space 1
is
scheduled to rendezvous with periodic
Comet
Borrelly today.
Explanation:
A pinpoint of light from a star that exploded over
10 billion light-years away
is centered in the panel at the lower right,
a cosmic
snapshot of the most
distant supernova.
The ancient stellar detonation
was detected
by digitally subtracting before and
after images of a faint, yellowish, elliptical galaxy
included in the Hubble Space Telescope Deep
Field image illustrated at the top and left.
Remarkable in itself as the
farthest known supernova, its measured
brightness provides astounding
evidence for
a strange universe -
one which eventually
defies gravity and expands at an
accelerating rate.
The unseen force driving
this
expansion is attributed to
"dark energy"
and discovering the fundamental
nature
of dark energy has been called
the challenge of this millennium.
Explanation:
Officially the
Chandra
Deep Field - South, this picture represents the deepest ever
x-ray image of the Universe.
One million seconds of accumulated exposure time with the orbiting
Chandra X-ray Observatory went in to its making.
Concentrating on a single, otherwise unremarkable patch
of sky in the constellation
Fornax,
this x-ray image corresponds to the
visible light Hubble Deep Field - South
released in 1998.
Chandra's view, color coded with low energies in red, medium in green,
and high-energy x-rays in blue, shows many faint sources of relatively
high-energy x-rays.
These are likely active galaxies feeding supermassive central
black holes
and large clusters of galaxies
at distances of up to 12 billion light-years.
The stunning picture supports
astronomers' ideas
of a youthful
universe
in which massive black holes were much more dominant
than at present.
Explanation:
Radio waves,
like visible light, are
electromagnetic radiation
and radio telescopes can "see" --
their signals translate into
radio images
of the cosmos.
While individually
even the largest
radio telescopes have
very blurry vision compared
to their
optical
counterparts, networks of
radio telescopes can combine signals to
produce
sharper pictures.
In fact, using an
NRAO
supercomputer in New Mexico, USA and technique called
VLBI
(Very Long Baseline Interferometry), the
European
network of radio telescopes
(EVN)
has produced pictures of distant galaxies at a resolution
some three times higher than the Hubble Space Telescope.
Penetrating obscuring dust,
the false-color EVN
radio images are inset above
according to their relative location in
an optical image of the famous
Hubble Deep Field region of the sky.
(Yellow lines superimposed on the optical image are
radio intensity contours from a single telescope.)
The bright cosmic radio source in the middle of each inset
corresponds to a galaxy.
Impressively, the radio sources appear to be so small,
less than about 600 light-years across in
actual size, that they are thought
to be associated
with massive central black holes
in the distant deep field galaxies.
Explanation:
At full throttle the
Deep Space 1 spacecraft's
innovative ion drive
produces about 1/50th of a pound of thrust ... a force so great
that it would
just about
hold up a piece of paper on planet Earth!
Still, powered by solar arrays
ion propulsion
systems can run continuously.
For long duration space missions they ultimately
win out
over the powerful
but brief blasts of less efficient
chemical rockets.
Deep Space 1 is
seen
here suspended in an assembly room, a folded
solar array
resting above the circular ion propulsion module.
Already a successful
technology
demonstrator with experimental
autonomous software,
the spacecraft flew by
asteroid 9969 Braille in July of 1999 but
later that year, in November, the robot probe was
nearly lost
due to the failure of its wide-field star tracker camera.
Now, the
adventures
of Deep Space 1 can continue.
Engineers were able to reprogram the navigation
system to utilize another on-board camera and on 28 June 2000
the ion drive was throttled up.
Once again
steering by the stars, Deep Space 1 is
presently
bound for a September 2001 rendezvous with periodic
Comet
Borrelly.
Explanation:
Galaxies like
colorful pieces of candy fill the
Hubble Deep Field - one of
humanity's most distant
optical views of the Universe.
The dimmest, some as faint as 30th magnitude
(about four billion times fainter than stars visible to the unaided eye),
are very distant galaxies and represent what
the Universe looked like in the
extreme past, perhaps less than one billion years after the
Big Bang.
To make the Deep Field image, astronomers
selected an uncluttered area of the sky in the
constellation Ursa Major (the Big Bear) and
pointed the Hubble Space Telescope
at a single spot for 10 days accumulating and combining
many separate exposures. With each
additional exposure, fainter
objects were revealed.
The final result can be used to explore the
mysteries of galaxy evolution and the infant
Universe.
Explanation:
Among the faintest objects are some
of the most unusual objects. The
Hubble Deep Field South was
released after much anticipation earlier this month,
delivering a
unique view of some of the most
distant parts of our universe. Part of this field is shown above.
Numerous astronomers are currently poring over this field,
trying to find clues about
young galaxies,
cosmological curvature, and
dark matter.
Clearly, visible among galaxies as dim as
magnitude 30 in
this long-duration exposure (and in the original
Hubble Deep Field North) are many
peculiar looking galaxies.
One interesting artifact is the blue arc just
to the upper right of the large galaxy near the image center.
This arc may be light from a more distant galaxy focused by the
gravitational lens effect
of the nearer galaxy.
Explanation:
This new deep view of the cosmos
is the sequel to the 1995 hit
Hubble Space Telescope Deep Field.
Billed as
the Hubble Deep Field South, it was produced
by pointing the space telescope toward a patch
of sky in the
southern constellation Tucana.
Over a period of 10 days, many separate exposures were accumulated
and combined to reveal progressively fainter galaxies.
The original deep field was constructed by observing a piece of sky
in the
northern constellation Ursa Major.
Both stare down 12 billion light-year long tunnels
to far-off and still mysterious times when
young galaxies inhabited
an infant universe.
Hubble Deep Field South observations were released to an
enthusiastic
audience on November 23, 1998.
Explanation:
Space travel entered the age of the ion drive
Saturday
with the launch of
Deep Space 1,
a NASA mission designed primarily to test new technologies.
Deep Space 1 is bound for asteroid
1992 KD in July 1999.
Although the
ion drive on Deep Space 1 provides
acceleration much smaller than we feel toward
Earth,
it will gradually give the spacecraft the speed it
needs to travel across our
Solar System. The
propulsion drive works by ionizing
Xenon atoms with power provided by
large panels that collect sunlight.
As these
ions are expelled by a strong electric field out the back, the spacecraft slowly gains speed.
Pictured above, hot blue ions emerge from a prototype drive that was
successfully tested last year at
JPL.
Explanation:
Galaxies this faint have never been seen before.
In 1996 the
Hubble Space Telescope (HST)
created one of the most famous pictures of
modern astronomy, the
Hubble Deep Field (HDF).
Now HST has returned to a piece of the HDF for a
long exposure by its new
NICMOS camera,
sensitive to
infrared light. The resulting image,
shown above in representative color,
shows known galaxies in a new light,
and previously unknown galaxies probably farther
than anything ever seen before. Galaxies as dim as
magnitude 30 are visible. Astronomers are learning from the
HDF
how different the young universe was from the
familiar universe of today.
Explanation:
What happens if you point a large telescope at nothing?
The above New Technology Telescope SUSI
Deep Field photograph isolated a small patch of
sky picked to contain no bright objects at all.
A very long exposure was then taken, similar to the
Hubble Deep Field,
in order to see the many faint objects that are usually
washed out by the light of
bright foreground objects.
What remains is a cosmic wallpaper rich in
distant galaxies.
Galaxies as faint as magnitude 26 were found to be irregularly distributed,
with several unusual pairings of different colored objects.
This and
other deep field images are being
released for detailed inspection by anyone interested.
New deep field images are being planned.
Explanation:
Galaxies like
colorful pieces of candy fill the
Hubble Deep Field -
humanity's most distant yet
optical view of the Universe.
The dimmest, some as faint as 30th magnitude
(about four billion times fainter than stars visible to the unaided eye),
are the most distant galaxies and represent what
the Universe looked like in the
extreme past, perhaps less than one billion years after the
Big Bang.
To make the Deep Field image, astronomers
selected an uncluttered area of the sky in the
constellation Ursa Major (the Big Bear) and
pointed the Hubble Space Telescope
at a single spot for 10 days accumulating and combining
many separate exposures. With each additional exposure, fainter
objects were revealed.
The final result can be used to explore the
mysteries of galaxy evolution and the infant
Universe.
Explanation:
Where do
gamma-ray bursts (GRBs) originate? The most powerful
explosions in the universe have
recently been located with record accuracy.
But do GRBs occur in galaxies or out alone in deep space?
This picture
taken with the
Hubble
Space Telescope of the field surrounding
GRB 970228 might provide a clue.
It appears to show an extended structure to the lower right of the
GRB, which is identified with an arrow.
Many astronomers speculate that this extended structure is a
distant galaxy, as its colors and subsequent
steady emission indicate. Other astronomers worry that the extended
emission is variable and so cannot be a galaxy. Astronomers hoping for
more cases to study were rewarded just last Monday with a new, well-located event:
GRB 970616. The location of this burst was determined by an unprecedented
collaboration involving the tandem use of NASA satellites
Compton,
Ulysses and
Rossi.
Explanation:
Galaxies like
colorful pieces of candy fill the
Hubble Deep Field -
humanity's most distant yet
optical view of the Universe.
The dimmest, some as faint as 30th magnitude
(about four billion times fainter than stars visible to the unaided eye),
are the most distant galaxies and represent what
the Universe looked like in the
extreme past, perhaps less than one billion years after the
Big Bang.
To make the Deep Field image, astronomers
selected an uncluttered area of the sky in the
constellation Ursa Major (the Big Bear) and
pointed the Hubble Space Telescope
at a single spot for 10 days accumulating and combining
many separate exposures. With each additional exposure, fainter
objects were revealed.
The final result can be used to explore the
mysteries of galaxy evolution and
the infant Universe.
Explanation:
Researchers believe that the faint reddish smudge indicated
by the arrow in the image above is
a candidate for the most distant known galaxy
which may have existed only a few hundred million years after
the Big Bang. The image is part of
the Hubble Deep Field, the Hubble
Space Telescope's deepest yet picture of the Universe. Made in December
1995 by staring for ten consecutive days with the Hubble, astronomers
have been intently
studying the resulting deep field image
filled with remote galaxies for
clues to what galaxies and the Universe looked like in the distant past.
While nearby galaxies are easily detected in the image -
some seen here have visible elliptical and even spiral structures -
the most distant (and therefore oldest) galaxies
must be identified by examining their appearance in
different wavelengths of light.
Based on this technique,
six of the most distant galaxies in the Deep Field appear to be farther
away than even quasars.
Explanation:
The image above is part of the
Hubble Deep Field and represents
humanity's most distant yet
optical view of the Universe. Galaxies like
colorful pieces of candy fill the field, some as faint as 30th magnitude
(about four billion times fainter than stars visible to the unaided eye).
The dimmest objects are the most distant galaxies and reveal what
the Universe looked like in the
extremely distant past, perhaps less than one billion years after the
Big Bang.
To make the Deep Field image, astronomers selected an uncluttered
area of the sky in the
constellation
Ursa Major (the Big Dipper) and
pointed the Hubble Space Telescope
at a single spot for 10 days accumulating and combining
many separate exposures. With each additional exposure, fainter
objects were revealed.
The final result can be used to explore the
mysteries of galaxy evolution and the infant Universe.
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