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Beneath Jupiter's Clouds
http://antwrp.gsfc.nasa.gov/apod/image/jupclouds_nasairtf.gi...
Submitted by APOD
168 months, 2 weeks, 2 days, 7 hours ago
This near-infrared image of Jupiter was made
using instrumentation at NASA's Infrared Telescope
Facility, located on the summit of Mauna Kea,
Hawaii,
in support of the
Galileo mission to Jupiter.
The brightest spots indicated by the false red shading
are relatively clear areas and represent
glimpses beneath the outer layer of
Jupiter's obscuring cloud tops.
On December 7, 1995 a
probe from the Galileo spacecraft parachuted
through these clouds for 57 minutes before melting, all the while
providing the first direct sampling of the
conditions there.
In a recent press release of the probe's findings scientists
announced some surprising results.
Discoveries based on probe data included
a new radiation belt 31,000 miles above the cloud tops,
relatively constant high velocity winds (up to
330 mph), no obvious water clouds, low abundances of Helium and Neon,
lightning occurring only 1/10th as
much as on Earth, and unexpectedly high temperatures.
The Galileo orbiter continues its two-year mission to explore the
Jovian system.
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Betelgeuse, Betelgeuse, Betelgeuse
http://antwrp.gsfc.nasa.gov/apod/image/hst_betelg.gif
Submitted by APOD
168 months, 2 weeks, 3 days, 7 hours ago
Betelgeuse
(sounds a lot like "beetle juice"),
a red supergiant star about 600 lightyears distant, is shown here in this
Hubble Space Telescope
image
which represents the first direct
picture of the surface of a star other than the Sun.
While
Betelgeuse
is cooler than the Sun, it is more massive and over
1000 times larger - if placed at the center of
our Solar System,
it would extend past the orbit of Jupiter.
This image reveals a bright, as yet unexplained hotspot on its surface.
Betelgeuse
is also known as Alpha Orionis, one of the
brightest stars
in the
familar constellation of
Orion, the Hunter.
Like many
star names,
Betelgeuse is
Arabic in origin. It is derived from a phrase which
refers to the hunter's shoulder
or armpit, the general area occupied by this star in drawings of the
figure in the
constellation.
As a massive red supergiant, it is
nearing the end of its life and will soon become a
supernova.
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Mercury's Faults
http://antwrp.gsfc.nasa.gov/apod/image/merfault_m10.gif
Submitted by APOD
168 months, 2 weeks, 4 days, 7 hours ago
The
surface of the planet
Mercury is not without fault. In this case,
however, "fault" refers to unusual surface features that are the topic of
much speculation. The above fault line is called Santa Maria Rupes, and
runs through many prominent craters. The meandering feature is thought to
be the result of huge forces of compression on
Mercury's surface. Such rupes probably originate from
large impacts
and a general shrinking of
Mercury's crust,
which in turn causes parts of the crust to push above other parts.
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Mercury's Caloris Basin
http://antwrp.gsfc.nasa.gov/apod/image/caloris_m10.gif
Submitted by APOD
168 months, 2 weeks, 5 days, 7 hours ago
Mercury, the closest planet to the
Sun, has a surface with so many craters
it resembles the
Earth's
Moon. The largest surface feature on
Mercury is the Caloris Basin, which resulted from a collision with an
asteroid.
The basin, which is more that 1000 kilometers across, is visible
as the large circular feature at the bottom of the above photograph.
Similar features, such as the Mare Orientale,
are seen on the Moon.
The Caloris Basin gets very hot because it is near the "sub-solar point" - the
point on
Mercury's surface
that is directly under the
Sun when
Mercury
is closest to the Sun.
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The Dusty Disk of Beta Pic
http://antwrp.gsfc.nasa.gov/apod/image/hst_betapic.gif
Submitted by APOD
168 months, 2 weeks, 6 days, 7 hours ago
This dusty disk,
viewed edge on surrounding
Beta Pictoris,
a star only 50 lightyears distant,
may signal the presence of an
infant solar system.
Beta Pictoris
is a young Sun-like star just completing
its formative stages.
About 10 years ago it made the news when astronomers detected
a disk around the star because
planets
are expected to form in such
circumstellar disks.
Did planets form around
Beta Pic?
The above recent Hubble Space Telescope image
offers supporting evidence that they did.
In this false color image,
the overwhelming light from the star itself is masked out
and features of the inner disk are revealed. The inner part
(white area) appears to be slightly warped with respect to the line
centered on the axis of the outer parts of the disk. This warp could
be caused by a large planet orbiting within the inner clear zone,
too faint to be seen directly against the stellar glare.
If so, this is an indication that
planetary systems are
common in our galaxy.
Is anybody out there?
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MyCn18: An Hourglass Nebula
http://antwrp.gsfc.nasa.gov/apod/image/hst_hourglass.gif
Submitted by APOD
168 months, 3 weeks, 7 hours ago
The sands of time are running out for the central star
of this hourglass-shaped
planetary nebula.
With its nuclear fuel
exhausted, this brief, spectacular, closing phase of a
Sun-like
star's life
occurs as its outer layers are ejected - its core becoming a cooling, fading
White Dwarf.
Astronomers have recently used the
Hubble Space Telescope (HST)
to make a series of
images of planetary nebulae, including
the one above.
Here, delicate rings of colorful glowing gas
(nitrogen-red, hydrogen-green, and oxygen-blue)
outline the tenuous walls of the "hourglass".
The unprecedented sharpness of the HST images has
revealed
surprising details
of the nebula ejection process
and may help resolve the outstanding mystery
of the variety of complex
shapes and symmetries of planetary nebulae.
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NGC 7027: A Dying Star's Nebula
http://antwrp.gsfc.nasa.gov/apod/image/hst_NGC7027.gif
Submitted by APOD
168 months, 3 weeks, 1 day, 7 hours ago
This pseudo-color composite of two recent
Hubble Space Telescope images
is a picture of a Sun-like star nearing the end of its
lifetime.
The exquisite details
visible in this planetary nebula
indicate that
when the star passed through its
Red Giant phase
it initially
shrugged off its outer atmosphere gently
and evenly producing the outer faint
spherical shells. As the process continued, material was apparently
ejected in dense clumps producing dust clouds in
the bright inner regions.
The whole ejection process was amazingly rapid, taking only
a few thousand years compared to a 10 billion year lifetime typical
for Solar type stars. In the end the hot stellar core,
now a white dwarf star,
was left - seen here as a white dot
at the center of the nebula.
Our middle-aged Sun will experience a
similar fate ... in about 5 billion years!
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Wild Duck Open Cluster M11
http://antwrp.gsfc.nasa.gov/apod/image/m11_aat.gif
Submitted by APOD
168 months, 3 weeks, 2 days, 7 hours ago
Many stars like our
Sun were formed in
open
clusters. The above open cluster,
M11, contains thousands of stars and
is just over three thousand light years distant. The stars in
this cluster all
formed together about 150 million years ago. The many bright stars in the
cluster appear blue.
Open clusters, also
called galactic clusters,
contain fewer and younger stars than
globular clusters. Also unlike
globular clusters,
open clusters are generally confined to the
plane of our Galaxy.
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The Dawn of the Clusters
http://antwrp.gsfc.nasa.gov/apod/image/clushighz_hst.gif
Submitted by APOD
168 months, 3 weeks, 3 days, 7 hours ago
What did the
universe look like near the beginning?
This exciting
photo by the
Hubble Space Telescope is one of the deepest ever
taken, and shows
galaxies as far away as ever before photographed.
The universe back then - when only one third of its present
age - was a
strange and violent place. Back then a large fraction of galaxies were
colliding and
interacting. In fact, the shapes of many
galaxies in the above photo are more distorted than most
nearby galaxies.
At this early universe epoch many
clusters of galaxies were just forming.
The bright twisted group of galaxies below the photographs center contains
the energetic radio galaxy 3C324.
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A Distant Cluster of Galaxies
http://antwrp.gsfc.nasa.gov/apod/image/clusmedz_hst.gif
Submitted by APOD
168 months, 3 weeks, 4 days, 7 hours ago
Every bright object in
this 1994
photograph by the
Hubble Space Telescope is a
galaxy. Oddly - most of the objects are
spiral galaxies. This rich
cluster of galaxies, named
CL
0939+4713, is almost half way
across the visible universe. Photos like this indicate that
clusters in the past contained a higher fraction of
spirals than do
nearby clusters, which are usually dominated by
elliptical galaxies.
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