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IC 5146: The Cocoon Nebula
Inside the Cocoon Nebula is a newly developing cluster of stars.
Cataloged as
IC 5146 , the beautiful nebula is nearly 15
light-years wide, located
some 4,000 light years away toward the northern constellation
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 an otherwise 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
clears out
a cavity in the molecular
cloud's star forming dust and gas.
This color view
of the Cocoon Nebula traces remarkably
subtle features within and surrounding the dusty
stellar
nursery .
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47 Tuc: A Great Globular Cluster of Stars
Stars come in bunches.
Of the over 200
globular star clusters that orbit the
center of our Milky Way Galaxy ,
47 Tucanae is the second brightest globular cluster
(behind Omega Centauri ).
Light takes about 13,000 years to reach us from
47 Tuc
which can be seen on the sky near the
Small Magellanic Cloud
in the southern constellation of
Tucana .
Also known as NGC 104, the dense cluster is made up
of several million stars in a volume only about 120 light-years across.
Its population of
red giant stars
are particularly easy to see
in this picture .
The globular cluster is also home to exotic
x-ray binary star systems.
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NGC 7008: The Fetus Nebula
http://antwrp.gsfc.nasa.gov/apod/image/0808/ngc7008_hagercol...
Submitted by APOD
2 days, 18 hours ago
Compact and round, NGC 7008 is recognized as a planetary nebula
about 2,800 light-years distant in the
nebula rich constellation of Cygnus.
This
impressive
telescopic view shows off NGC 7008's remarkable
colors and details by the skillfull combination of broad band and
narrow band images from two different telescopes with about
12 hours of total exposure time.
The intriguing assortment of features
within the nebula's approximately 1 light-year
diameter suggest its popular name, the Fetus Nebula, but
planetary nebulae
are not associated with star birth.
Instead, nebulae like NGC 7008 are produced during a
brief phase
that sun-like stars pass through toward the end of
their lives.
Ejecting their outer layers, the stars cool to eventually
become white dwarf stars ,
like the star seen near the center of NGC 7008.
This colorful image also includes an unrelated but still lovely
gold and blue binary star system just
below NGC 7008 .
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Grand Spiral Galaxy NGC 1232
Galaxies are fascinating not only for
what is visible, but for what is invisible.
Grand spiral galaxy
NGC 1232 ,
captured in detail by one of the new
Very Large Telescopes ,
is a good example.
The visible is dominated by millions of
bright stars and dark
dust ,
caught up in a gravitational swirl of
spiral arms rotating about the center.
Open clusters containing
bright blue stars can be seen sprinkled along these spiral arms,
while dark lanes
of dense interstellar
dust
can be seen sprinkled between them.
Less visible, but detectable, are billions of dim normal
stars and vast tracts of
interstellar gas ,
together wielding such high mass that they
dominate the dynamics of the inner
galaxy .
Invisible are even
greater amounts of matter
in a form we don't yet know - pervasive
dark matter needed to explain the
motions
of the visible in the outer galaxy.
What's out there?
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The Matter of the Bullet Cluster
http://antwrp.gsfc.nasa.gov/apod/image/0808/bullet_cluster_c...
Submitted by APOD
4 days, 18 hours ago
The
matter in galaxy cluster 1E 0657-56,
fondly
known as the "bullet cluster", is shown in
this
composite image .
A mere 3.4 billion light-years away,
the bullet cluster's individual galaxies are seen in the
optical image data, but their total
mass adds up to far less than
the mass of the cluster's two clouds of hot x-ray emitting gas
shown in red.
Representing even more mass than the optical galaxies and
x-ray gas combined, the blue hues show the distribution of dark
matter in the cluster .
Otherwise invisible to telescopic views, the
dark matter was mapped by
observations of
gravitational lensing
of background galaxies.
In a text book example of a shock front, the
bullet-shaped cloud of gas at the right was
distorted during the titanic collision
between
two galaxy clusters
that created the larger bullet cluster itself.
But the dark matter present has not interacted with the
cluster gas except by gravity.
The clear separation of
dark matter
and gas clouds is
considered direct
evidence
that dark matter
exists .
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Active Galaxy NGC 1275
http://antwrp.gsfc.nasa.gov/apod/image/0808/ngc1275_web59.jp...
Submitted by APOD
5 days, 18 hours ago
Active galaxy NGC 1275
is the central, dominant member of the large and
relatively nearby
Perseus Cluster of Galaxies .
A prodigious source of
x-rays
and
radio
emission, NGC 1275 accretes
matter as entire galaxies fall into it, ultimately
feeding a supermassive black hole at the galaxy's core.
This stunning
visible
light image from the Hubble Space Telescope
shows galactic debris
and filaments of glowing gas,
some up to 20,000 light-years long.
The filaments persist in NGC 1275, even though
the turmoil of galactic collisions should destroy them.
What keeps the filaments together?
Recent work
indicates that the structures, pushed out
from the galaxy's center by the black hole's activity, are
held together by magnetic fields.
To
add x-ray data
from the Chandra Observatory and radio data from
the Very Large Array
to the Hubble image, just slide
your cursor over the picture.
In the resulting composite , x-rays highlight the
shells of hot gas
surrounding the center of the galaxy, with radio emission filling
giant bubble-shaped cavities.
Also known as Perseus A,
NGC 1275
spans over 100,000 light years and
lies about 230 million light years away.
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August Moons
http://antwrp.gsfc.nasa.gov/apod/image/0808/AugMoon_mammana_...
Submitted by APOD
6 days, 18 hours ago
This August was
eclipse season .
The month's first New Moon and Full Moon were both seen in
darkened skies during a
solar and lunar eclipse.
Blocking the Sun, the left panel's New
Moon was captured
during the total solar eclipse of August 1 from the path of
totality overlooking Novosibirsk (Siberia) Reservoir,
locally known as the Ob Sea.
A lovely
solar corona
and bright inner planets Mercury and Venus emerged
during the total eclipse phase, while the flickering view screens
of eclipse watchers' digital cameras dotted the landscape.
On the right, the Full Moon grazed
Earth's shadow nearly
15 days later in a
partial lunar eclipse.
That
serene
view was recorded during an early evening stroll along
the shores of the Odet River near the city of Quimper
in western France.
For planet Earth there are about two seasons each year during
which the orientation of the Moon's orbit is
favorable for solar and lunar eclipses.
The next eclipse season begins in January 2009 with an annular
solar eclipse .
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Earth's Shadow
http://antwrp.gsfc.nasa.gov/apod/image/0808/LEumbralshadow_a...
Submitted by APOD
1 week, 18 hours ago
The dark, inner shadow of planet Earth
is called the umbra.
Shaped like a cone extending into space, the umbra has a
circular cross section that can be most easily seen during
a lunar eclipse.
For example, last Saturday
the Full Moon slid across the northern
edge of the umbra.
Entertaining
moon watchers throughout Earth's eastern hemisphere, the
lunar
passage created a deep but partial lunar eclipse.
This
composite image uses
successive pictures recorded during
the
eclipse from Athens, Greece to trace out a large part of the
umbra's curved edge.
The result nicely illustrates the relative size of the umbra's
cross section at the distance of the Moon, as well as the
Moon's path
through the Earth's shadow.
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NGC 6960: The Witch's Broom Nebula
http://antwrp.gsfc.nasa.gov/apod/image/0808/ngc6960_block.jp...
Submitted by APOD
1 week, 1 day, 18 hours ago
Ten thousand years ago, before the dawn of recorded human history,
a new light must suddenly have appeared in the
night sky and faded after a few weeks.
Today we know this light was an exploding star and record the colorful expanding cloud as the
Veil Nebula.
Pictured above is the west end of the
Veil Nebula known technically as
NGC 6960 but less formally as the
Witch's
Broom Nebula.
The expanding debris cloud gains its colors by sweeping up and
exciting existing nearby gas.
The supernova remnant
lies about 1400 light-years away towards the constellation of
Cygnus.
This Witch's Broom actually spans over three times the
angular size of the full
Moon.
The bright star 52
Cygnus is visible with the unaided eye from
a dark location but unrelated to the ancient
supernova.
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Baily's Beads near Solar Eclipse Totality
http://antwrp.gsfc.nasa.gov/apod/image/0808/bailysbeads_durm...
Submitted by APOD
1 week, 2 days, 18 hours ago
Just before the Sun blacks out, something strange occurs.
As the Moon moves to completely cover the Sun in a
total solar
eclipse, beads of bright sunlight stream
around the edge of the Moon.
This effect, known as
Baily's beads,
is named after
Francis Baily
who called attention to the
phenomenon
in 1836.
Although, the number and brightness of
Baily's beads used to be unpredictable,
today the Moon
is so well mapped that general features regarding Baily's beads are expected.
When a single bead dominates, it is called the
diamond ring effect,
and is typically seen just before totality.
Pictured above, a series of images recorded Baily's beads at times
surrounding the recent total solar eclipse
visible from
Novosibirsk,
Russia.
The complete series can be seen by scrolling right.
At the end of totality, as the Sun again emerges from behind the moon,
Baily's beads
may again be visible -- but now on the other side of the Moon.
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