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Enceladus Ice Geysers
http://antwrp.gsfc.nasa.gov/apod/image/0710/PIA08386_encelad...
Submitted by APOD
13 months, 3 weeks, 4 days, 22 hours ago
Ice geysers erupt on
Enceladus,
bright and shiny inner moon of Saturn.
Shown in
this
false-color image, a backlit view of the moon's southern
limb, the majestic, icy plumes were discovered by
instruments on the Cassini Spacecraft during close encounters
with Enceladus in November of 2005.
Eight source locations
for these geysers have now been identified
along substantial
surface fractures
in the moon's south polar region.
Researchers suspect the
geysers
arise from near-surface
pockets of liquid water with
temperatures
near 273 kelvins (0 degrees C).
That's hot when compared to the distant
moon's surface temperature of 73 kelvins (-200 degrees C).
The cryovolcanism
is a dramatic sign that tiny,
500km-diameter Enceladus is surprisingly active.
Enceladus ice geysers also likely produce Saturn's faint but extended E
ring.
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Bright Planets, Crescent Moon
http://antwrp.gsfc.nasa.gov/apod/image/0710/Early-Bird-Speci...
Submitted by APOD
13 months, 3 weeks, 6 days, 22 hours ago
Early risers are currently enjoying
the sight of
dazzling Venus,
near the eastern horizon as the
morning star.
Recorded on October 7, this predawn
skyview
does feature Venus at the upper right.
It also includes a crescent Moon and Saturn (lower left).
In fact, holding your fist at arms length would have
easily covered
both planets and the Moon in this 5 degree wide field.
Earthshine,
sunlight reflected from planet Earth's dayside, illuminates
features on the lunar nightside.
A close inspection of Saturn itself reveals
a nearby pinpoint of light corresponding
to
Saturn's large moon Titan.
Though the Moon has moved on,
the tight triangle formed by Venus, Saturn,
and Regulus (top), alpha star in the constellation Leo, will
continue to look impressive
in early morning skies over the next few days.
Early bird astrophotographer Jay Ouellet also described
Mars as a "brilliant red diode" in
his dark country sky east of Quebec City, Canada.
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Aurora, Stars, Meteor, Lake, Alaska
http://antwrp.gsfc.nasa.gov/apod/image/0710/aurora_kuenzli.j...
Submitted by APOD
13 months, 4 weeks, 1 day, 22 hours ago
Sometimes, after your eyes adapt to the dark, a spectacular sky appears.
In this case, a picturesque lake lies in front of you, beautiful green
aurora flap high above you, brilliant stars shine far in the distance, and, for a brief moment, a
bright meteor streaks by.
This digitally fused breathtaking panorama was captured late last month across one of the
Chena Lakes
in
North Pole,
Alaska,
USA, and includes the
Pleiades
open cluster of stars on the image right.
The shot is unusual not only for the
many wonders it has captured simultaneously,
but because lakes this far north tend to freeze and become
non-reflecting before a
sky this dark can be photographed.
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Galaxy NGC 474: Cosmic Blender
http://antwrp.gsfc.nasa.gov/apod/image/0710/ngc474_schirmer....
Submitted by APOD
14 months, 22 hours ago
What's happening to galaxy NGC 474?
The multiple layers of emission appear strangely complex and unexpected given the relatively featureless appearance of the elliptical galaxy in less deep images.
The cause of the shells is currently unknown, but possibly
tidal tails related to debris left over from absorbing
numerous small galaxies in the past billion years.
Alternatively the shells may be like ripples in a pond,
where the ongoing collision with the spiral galaxy to the right of
NGC 474
is causing density
waves to
ripple though the galactic giant.
Regardless of the actual cause, the
above image dramatically highlights the increasing consensus that the
outer halos of most
large galaxies are not really smooth
but have complexities induced by frequent interactions with -- and accretions of --
smaller nearby galaxies.
The halo of our own
Milky Way Galaxy
is one example of such
unexpected complexity.
NGC 474 spans about 250,000
light years
and lies about 100 million light years distant toward the constellation of the Fish
Pisces.
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X-ray Stars of Orion
http://antwrp.gsfc.nasa.gov/apod/image/0710/orion_xray_c.jpg
Submitted by APOD
14 months, 2 days, 22 hours ago
The stars of Orion shine brightly
in visible light in planet Earth's night sky.
The
constellation harbors the closest large stellar nursery,
the Great Nebula of Orion,
a mere 1,500 light-years away.
In fact, the apparently bright clump of stars near the center
of this false color Chandra
x-ray telescope picture
are the massive stars of
the Trapezium - the
young star cluster which powers much of the nebula's
visible-light glow.
The stars shown
in blue and orange are young sun-like stars; prodigious sources
of x-rays thought to be produced in hot
stellar coronae and
surface flares in a young star's strong
magnetic field.
Our middle-aged
Sun itself was
probably thousands of times
brighter in x-rays when, like
the
Trapezium stars, it was
only a few million years old.
The
x-ray image
spans about 2.5 light-years
across the central region of the Orion Nebula.
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