Astronomy Picture of the Day |
APOD: 2023 August 19 - Ringed Ice Giant Neptune
Explanation:
Ringed ice giant Neptune
lies near the center of this sharp
near-infrared image from the
James Webb Space Telescope.
The dim and distant world is the
farthest planet from the Sun,
about 30 times farther away than planet Earth.
But in the stunning Webb view, the planet's dark and ghostly appearance
is due to atmospheric methane that absorbs infrared light.
High altitude clouds that reach above most of Neptune's absorbing methane
easily stand out in the image though.
Coated with frozen nitrogen, Neptune's largest moon Triton is
brighter than Neptune in reflected sunlight,
seen at the upper left sporting the Webb telescope's characteristic
diffraction spikes.
Including Triton, seven of Neptune's 14 known moons can be
identified
in the field of view.
Neptune's faint rings
are striking in this space-based
planetary portrait.
Details of the complex ring system are seen here for the first
time since Neptune was visited by the
Voyager 2 spacecraft in August 1989.
APOD: 2023 May 27 - Crescent Neptune and Triton
Explanation:
Gliding through the outer
Solar System,
in 1989 the
Voyager 2 spacecraft
looked toward the Sun to find this view of most distant planet Neptune
and its moon
Triton together in a crescent phase.
The elegant image of
ice-giant planet
and
largest moon
was taken from behind just after Voyager's
closest approach.
It could not have been taken from
Earth because the most distant planet never shows a crescent phase
to sunward eyes.
Heading for the
heliopause and beyond,
the spacecraft's
parting vantage
point also robs Neptune of its familiar blue hue.
APOD: 2022 September 23 - Ringed Ice Giant Neptune
Explanation:
Ringed, ice giant Neptune
lies near the center of this sharp
near-infrared image from the
James Webb Space Telescope.
The dim and distant world is the
farthest planet from the Sun,
about 30 times farther away than planet Earth.
But in the stunning Webb view the planet's dark and ghostly appearance
is due to atmospheric methane that absorbs infrared light.
High altitude clouds that reach above most of Neptune's absorbing methane
easily stand out in the image though.
Coated with frozen nitrogen, Neptune's largest moon Triton is
brighter than Neptune in reflected sunlight and is seen at upper left
sporting the Webb's characteristic
diffraction spikes.
Including Triton, seven of Neptune's 14 known moons can be
identified
in the field of view.
Neptune's faint rings
are striking in this new space-based planetary portrait.
Details of the complex ring system are seen here for the first
time since Neptune was visited by the
Voyager 2 spacecraft in August 1989.
APOD: 2021 July 25 - Crescent Neptune and Triton
Explanation:
Gliding silently through the outer
Solar System, the
Voyager 2 spacecraft camera captured
Neptune and
Triton together in crescent phase.
The elegant picture of the
ice-giant planet and its
cloudy moon was taken from behind just after
closest approach in 1989.
It could not have been taken from
Earth because
Neptune never shows a crescent phase to sunward Earth.
The
unusual vantage point also robs
Neptune of its familiar blue hue,
as sunlight seen from here is scattered forward,
and so is reddened like the
setting Sun.
Neptune is smaller but more massive than
Uranus, has several
dark rings, and
emits more light than it receives from the Sun.
APOD: 2014 August 26 - Flying Past Neptune's Moon Triton
Explanation:
What would it look like to fly past Triton, the largest moon of planet Neptune?
Only one spacecraft has ever done this -- and now, for the first time, images of this dramatic encounter have been
gathered into a
movie.
On 1989 August 25, the Voyager 2 spacecraft shot through the Neptune system with
cameras blazing.
Triton is slightly smaller than Earth's Moon but has
ice volcanoes
and a surface rich in
frozen nitrogen.
The first sequence in
the video
shows Voyager's approach to
Triton, which, despite its
unusual green tint, appears in approximately true color.
The mysterious terrain seen under the spacecraft soon changed from light to dark, with the
terminator of night soon crossing underneath.
After closest approach,
Voyager pivoted to see the departing moon, now visible as a diminishing
crescent.
Next July, assuming all goes well, the robotic
New Horizons
spacecraft will make a similar flight past
Pluto, an orb of similar size to Triton.
APOD: 2014 May 15 - Voyager's Neptune
Explanation:
Cruising through the outer solar system, the Voyager 2
spacecraft made its closest
approach
to Neptune on August 25, 1989,
the only spacecraft to visit the most distant
ice giant planet.
Based on the images recorded during its close encounter
and in the following days,
this inspired composited scene covers the
dim outer planet, largest
moon Triton, and faint system of rings.
From just beyond Neptune's orbit, the interplanetary perspective
looks back toward the Sun, capturing
the planet and Triton as thin
sunlit crescents.
Cirrus clouds and a dark band
circle Neptune's south polar region,
with a cloudy vortex above the pole
itself.
Parts of the very
faint ring system along with
the three bright ring arcs were first imaged by Voyager during the
fly-by, though the faintest segments are modeled in this
composited picture.
Spanning 7.5 degrees, the background starfield is composed
from sky survey data centered on the constellation Camelopardalis,
corresponding to the outbound Voyager's view of the
magnificent Neptunian system.
APOD: 2013 April 14 - Crescent Neptune and Triton
Explanation:
Gliding silently through the outer
Solar System, the
Voyager 2 spacecraft camera captured
Neptune and
Triton together in crescent phase in 1989.
The elegant picture of the
gas giant planet and its
cloudy moon
was taken from behind just after
closest approach.
It could not have been taken from
Earth because
Neptune never shows a crescent phase to sunward Earth.
The
unusual vantage point also robs
Neptune of its familiar
blue hue,
as sunlight seen from here is scattered forward,
and so is reddened like the
setting Sun.
Neptune is smaller but more massive than
Uranus, has several
dark rings, and emits more light than it receives from the Sun.
APOD: 2009 December 13 - Crescent Neptune and Triton
Explanation:
Gliding silently through the outer
Solar System, the
Voyager 2 spacecraft camera captured
Neptune and
Triton together in crescent phase in 1989.
The above picture of the
gas giant planet and its
cloudy moon
was taken from behind just after
closest approach.
It could not have been taken from
Earth because
Neptune never shows a crescent phase to sunward Earth.
The
unusual vantage point also robs
Neptune of its familiar
blue hue,
as sunlight seen from here is scattered forward,
and so is reddened like the
setting Sun.
Neptune is smaller but more massive than
Uranus, has several
dark rings, and emits more light than it receives from the Sun.
APOD: 2007 March 4 - Triton: Neptunes Largest Moon
Explanation:
In October of 1846,
William Lassell
was observing the newly discovered planet
Neptune.
He was attempting to confirm his observation, made just the previous week,
that Neptune had a ring.
But this time he discovered that Neptune had a satellite as well.
Lassell soon proved that the ring was a product of his new
telescope's distortion, but the satellite
Triton
remained.
The above picture of
Triton
was taken in 1989 by the only spacecraft ever to pass
Triton:
Voyager 2.
Voyager 2 found fascinating terrain,
a thin atmosphere, and even evidence for
ice volcanoes
on this world of peculiar orbit and spin.
Ironically, Voyager 2 also confirmed the existence of
complete thin rings around Neptune
- but these would have been quite
invisible
to Lassell!
APOD: 2006 June 18 - Crescent Neptune and Triton
Explanation:
Gliding silently through the outer
Solar System, the
Voyager 2 spacecraft camera captured
Neptune and
Triton together in crescent phase in 1989.
The above picture of the
gas giant planet and its
cloudy moon
was taken from behind just after closest approach.
It could not have been taken from
Earth because
Neptune never shows a crescent phase to sunward Earth.
The
unusual vantage point also robs
Neptune of its familiar
blue hue,
as sunlight seen from here is scattered forward,
and so is reddened like the
setting Sun.
Neptune is smaller but more massive than
Uranus, has several
dark rings, and emits more light than it receives from the Sun.
APOD: 2003 October 20 - Neptune and Triton from Palomar
Explanation:
How's the weather on Neptune?
Tracking major
weather patterns on the
Solar System's outermost gas giant can help in the
understanding of global weather patterns here on
Earth.
Each summer for the past five years,
Neptune has been imaged and major weather patterns studied.
The latest picture, taken on September 15, is
shown above in false color.
Visible in pink near
Neptune's lower right is a
new storm dubbed Annabelle that is several times larger than her
terrestrial sister Isabel, a concurrent
storm system that occurred here on Earth.
Although Isabel lasted a few weeks, no one knows
how long Annabelle will endure.
On the upper right is
Neptune's largest moon
Triton, an
unusual moon that sports
volcanoes that spew ice.
APOD: 2001 October 18 - Pluto: New Horizons
Explanation:
Pluto's
horizon spans the foreground in this artist's vision,
gazing sunward across that distant and
not yet explored world.
Titled New Horizons, the painting also
depicts Pluto's
companion, Charon, as a darkened, ghostly apparition with
a luminous
crescent
against a starry background.
Beyond
Charon,
the diminished Sun is immersed in
a flattened cloud of zodiacal dust.
Here, Pluto's ruddy colors are based on existing
astronomical
observations while imagined but
scientifically tenable details
provided by the artist include high atmospheric cirrus and
dark plumes from surface vents, in analogy to Neptune's large moon
Triton
explored by the
Voyager
2 spacecraft in 1989.
Craters suggest bombardment by
Kuiper
Belt objects, a newly understood
population of
outer solar system bodies likely
related to the
Pluto-Charon system.
NASA is now considering a future robotic reconnaissance
mission
to Pluto-Charon and the Kuiper Belt which could reach the distant
worlds late in the next decade.
APOD: 2001 June 19 - Crescent Neptune and Triton
Explanation:
Gliding silently through the outer
Solar System, the
Voyager 2 spacecraft camera captured
Neptune and
Triton together in crescent phase in 1989.
The above picture of the
gas giant planet and its
cloudy moon
was taken from behind just after closest approach.
It could not have been taken from
Earth because
Neptune never shows a crescent phase to sunward Earth.
The
unusual vantage point also robs
Neptune of its familiar
blue hue,
as sunlight seen from here is scattered forward,
and so is reddened like the
setting Sun.
Neptune is smaller but more massive than
Uranus, has several
dark rings, and emits more light than it receives from the Sun.
APOD: October 10, 1999 - Triton: Neptune's Largest Moon
Explanation:
One hundred and fifty three years ago, on October 10th, 1846,
William Lassell
was observing the newly discovered planet
Neptune.
He was attempting to confirm his observation, made just the previous week,
that Neptune had a ring.
But this time he discovered
that Neptune had a satellite as well.
Lassell soon proved that the ring was a product of his new
telescope's distortion, but the satellite
Triton
remained.
The above picture of
Triton
was taken in 1989 by the only spacecraft ever to pass
Triton:
Voyager 2.
Voyager 2 found fascinating terrain,
a thin atmosphere, and even evidence for
ice volcanoes
on this world of peculiar orbit and spin.
Ironically, Voyager 2 also confirmed the existence of complete thin rings around Neptune
- but these would have been quite invisible to Lassell!
APOD: February 13, 1999 - Pluto: The Frozen Planet
Explanation:
This portrait of Pluto and its companion
Charon was taken by the Hubble Space Telescope in 1994.
Pluto is usually the most distant planet from the
Sun but because of its
eccentric orbit Pluto crossed inside
of Neptune's orbit in 1979.
On Thursday, February 11th, it crossed back out, recovering
its status as
the most distant of
nine planets.
Pluto is
still considered to be a planet, although very little
is known about it compared to other planets.
Pluto is smaller than any
other planet and even smaller than
several other planet's moons.
Pluto is probably composed of frozen rock and ice,
much like Neptune's moon Triton.
Pluto has not yet been
visited by a spacecraft, but a
mission is being planned for the next decade.
APOD: February 7, 1999 - Titan: Saturns Smog Moon
Explanation:
The largest moon of
Saturn is a rare wonder.
Titan is the only one of Saturn's moons
with an atmosphere, and one of only two moons in the
Solar System with this distinction
(Neptune's
Triton is the other).
Titan's thick cloudy atmosphere is mostly nitrogen,
like Earth's, but contains much
higher percentages of "smog-like" chemicals
such as methane and ethane. The smog may be so thick
that it actually rains "gasoline-like" liquids.
The organic nature of some of the chemicals found in
Titan's
atmosphere cause some to speculate that
Titan may harbor life!
Because of its thick cloud cover,
however, Titan's actual surface properties remain mysterious.
Voyager 1 flew by in 1980 taking the
above picture, and more recently much has been learned from
observations by the
Hubble Space Telescope.
The
Cassini mission
launched in 1997 will map Titan's surface in 2004, helping to solve some
of its mysteries.
APOD: February 21, 1998 - Neptune: Big Blue Giant
Explanation:
This picture was taken by the Voyager 2 spacecraft in 1989 - the only spacecraft
ever to visit Neptune. Neptune will be the farthest planet from the
Sun until 1999, when the
elliptical orbit of
Pluto
will cause it to once again resume this status. Neptune, like Uranus, is composed mostly of liquid water,
methane and ammonia, is surrounded by a thick gas
atmosphere of mostly hydrogen and helium,
and has many moons and rings. Neptune's moon
Triton is unlike any
other and has active volcanoes. The nature of
Triton's unusual orbit around
Neptune
is the focus of much discussion and speculation.
APOD: December 28, 1997 - Pluto: The Frozen Planet
Explanation:
The Hubble Space Telescope
imaged Pluto and its moon Charon in 1994.
Pluto is usually the most distant planet from the
Sun but because of its elliptic orbit Pluto crossed inside of
Neptune's
orbit in 1979 and will cross back out again in 1999.
Compared to the other planets,
very little is known about Pluto.
Pluto is smaller than any
other planet and even smaller than
several other planet's moons.
From Pluto, the Sun is just a tiny point of light.
Pluto is probably composed of frozen rock and ice,
much like Neptune's moon
Triton. Pluto has not yet been
visited by a spacecraft, but a
mission is being planned for the next decade.
APOD: November 23, 1997 - Triton: Neptune's Largest Moon
Explanation:
On October 10th, 1846,
William Lassell
was observing the newly discovered
planet Neptune. He was attempting
to confirm his observation, made just the previous week,
that Neptune had a ring.
But this time he discovered
that Neptune
had a satellite as well. Lassell soon proved that the ring
was a product of his new telescope's distortion, but the satellite
Triton
remained. The above picture of Triton
was taken in 1989 by the only spacecraft ever to pass Triton:
Voyager 2. Voyager 2 found fascinating terrain,
a thin atmosphere, and even evidence for ice volcanoes on this
world of peculiar orbit and spin. Ironically, Voyager 2 also confirmed the existence of complete thin rings around Neptune
- but these would have been quite invisible to Lassell!
APOD: May 26, 1997 - Old Faithful Meets Hale-Bopp
Explanation:
As Comet Hale-Bopp leaves our Northern Skies, it provides us with
yet another burst of joy.
On May 11th the fading
comet
was photographed behind the famous
"Old Faithful" water geyser of
Yellowstone National Park, Wyoming, USA, Planet Earth.
Perhaps more familiar to Earth Dwellers
than the dark geysers on
Neptune's moon
Triton, the gas geysers on
Jupiter's moon Io,
and the dirty water geysers hypothesized on Jupiter's
moon Europa,
Earth's Old Faithful is also reliable -
every 60-80 minutes it gushes a plume of water and
steam high into the air.
Comet Hale-Bopp
will continue to be visible
to observers in the Southern Hemisphere
as it moves away from the Sun towards the outer Solar System.
APOD: October 10, 1996 - Triton: Neptune's Largest Moon
Explanation: Today marks the 150th anniversary of the
discovery of Triton. On October 10 1846, William Lassell
was observing the newly discovered
planet Neptune. He was attempting
to confirm his observation, made just the previous week,
that Neptune had a ring.
But this time he discovered
that Neptune
had a satellite as well. Lassell soon proved the ring
was product of his new telescope's distortion, but the satellite
Triton
remained. The above picture of Triton
was taken in 1989 by the only spacecraft ever to pass Triton:
Voyager 2. Voyager 2 found fascinating terrain,
a thin atmosphere, and even evidence for ice volcanoes on this
world of peculiar orbit and spin. Ironically, Voyager 2 also confirmed the existence of complete thin rings around Neptune
- but these would have been quite invisible to Lassell!
APOD: March 4, 1996 - Uranus' Largest Moon: Titania
Explanation:
Titania's tortured terrain is a mix of valleys and craters. NASA's
interplanetary robot spacecraft Voyager 2 passed this moon of
Uranus in
1986 and took the above photograph. The photograph was then transmitted
back to earth by radio. The valleys of
Titania
resemble those on
Ariel indicate that Titania underwent some unknown
tumultuous resurfacing event in its distant past. Although
Titania is
Uranus' largest moon, it is still much smaller than
Triton - the largest
moon of Uranus' sister planet
Neptune. Titania is essentially a large dirty
iceball that orbits Uranus - it is composed of about half water-ice and
half rock. Titania was discovered by William Hershel in 1787.
APOD: November 4, 1995 - Neptune's Moon Proteus
Explanation:
Proteus is the second largest moon of
Neptune behind the mysterious
Triton.
Proteus was discovered only in 1982 by the Voyager 2 spacecraft. This is
unusual since Neptune has a smaller moon - Nereid - which was discovered
33 years earlier from Earth. The reason
Proteus was not discovered sooner
is that its surface is very dark and it orbits much closer to Neptune.
Proteus has an odd box-like shape and were it even slightly more
massive, its own gravity would cause it to reform itself into a sphere.
APOD: September 23, 1995 - Titan: Saturn's Smog Moon
Explanation:
The largest moon of
Saturn is a rare wonder. Titan is the only one of
Saturn's moons with an atmosphere, and one of only two moons in the
Solar System with this distinction
(Neptune's
Triton is the other).
Titan's
thick cloudy atmosphere is mostly nitrogen, like
Earth's, but contains much
higher percentages of "smog-like" chemicals such as methane and ethane.
The smog may be so thick that it actually rains
"gasoline-like" liquids. The organic nature of some of the chemicals found in
Titan's atmosphere cause some to speculate that Titan may harbor life!
Because of its thick cloud cover, however, Titan's actual surface properties
remain mysterious.
Voyager 1
flew by in 1980 taking the above picture,
and recently much has been learned from
Hubble Space Telescope
observations. The
Cassini mission
currently scheduled for launch in 1997 will map Titan's
surface, helping to solve some of its mysteries.
APOD: August 18, 1995 - Pluto: The Frozen Planet
Explanation:
The Hubble Space Telescope
imaged
Pluto and its moon Charon in 1994.
Pluto is usually the most distant planet from the
Sun but because of its elliptic
orbit Pluto crossed inside of
Neptune's orbit in 1979 and will cross back
out again in 1999. Compared to the other planets, very little is known
about Pluto.
Pluto is smaller than any other planet and even smaller than
several other planet's moons. From Pluto, the Sun is just a tiny point of
light.
Pluto is probably composed of frozen rock and ice, much like
Neptune's moon
Triton. Pluto has not yet been visited
by a spacecraft, but a
mission is being planned
for the next decade.
APOD: August 17, 1995 - Neptune: Big Blue Giant
Explanation:
This picture was taken by the
Voyager 2 spacecraft in 1986 - the only spacecraft ever to visit
Neptune.
Neptune will be the farthest planet from the
Sun until 1999, when the elliptical orbit of
Pluto will cause it to once again resume this status.
Neptune, like Uranus,
is composed mostly of liquid water, methane
and ammonia, is surrounded by a thick gas atmosphere of mostly hydrogen and
helium, and has many moons and rings.
Neptune's moon Triton is unlike any
other and has active volcanoes. The nature of
Triton's unusual orbit around
Neptune is the focus of much discussion and speculation.
APOD: August 5, 1995 - Geysers on Triton
Explanation:
In August of 1989 NASA's
Voyager 2
spacecraft passed by Neptune, the most distant of the solar system's gas
giant planets. Its encounter with Neptune climaxed with its closest approach
to Neptune's largest moon Triton. From a distance of about 24,000 miles
the robot space probe surveyed Triton's surface, whose temperature
averages nearly -400 degrees Fahrenheit, and discovered surprising evidence
of a complex and active world.
For example, the prominent dark streaks in this image seem to come from
small volcanoes and may
consist of nitrogen frost mixed with organic compounds ejected during
geyser-like eruptions.