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 combines three specific emitted colors
and was taken with the
0.9-meter telescope on
Kitt Peak,
Arizona,
USA.
Monday, April 16, 2012
Sunday, April 15, 2012
Fata Morgana: A Possibly Titanic Mirage
Labels: Astronomy Picture, Astronomy picture of the day
Did this mirage help sink the Titanic?
The optical phenomenon called
Fata Morgana can make
strange shapes or a
false wall of water appear above a watery horizon.
When conditions are right, light reflecting off of cold water will be
bent by an unusual layer of warm air above to arrive at the observer from several different angles.
A conceptually comparable
mirage can make a
setting Sun appear
strangely distorted or a
distant pavement appear wet.
One hundred years ago today, such a Fata Morgana mirage
might have obscured real
icebergs from the clear view of
crew onboard the
Titanic.
Additional evidence for this
distortion hypothesis arises from the nearby vessel
SS Californian which reported sightings consistent with
Fata Morgana mirages.
The above Fata Morgana mirage was taken off the US Pacific coast in 2008.
Saturday, April 14, 2012
Six Moons of Saturn
Labels: Astronomy Picture, Astronomy picture of the day
How many moons does Saturn have?
So far 62 have
been discovered, the smallest only a fraction
of a kilometer across.
Six of its largest satellites can be seen here, though, in a sharp
Saturnian family portrait
taken on March 9.
Larger than Earth's Moon and even slightly larger than Mercury,
Titan
has a diameter of 5,150 kilometers and starts the line-up
at the lower left.
Continuing to the right across the frame are
Mimas,
Tethys, [Saturn],
Enceladus,
Dione, and
Rhea at far right.
Saturn's first known natural satellite, Titan was
discovered in 1655 by
Dutch astronomer Christiaan Huygens, while most recently the
satellite provisionally designated
S/2009 S1 was found
by the Cassini Imaging Science Team in 2009.
Tonight,
Saturn reaches opposition
in planet Earth's sky, offering
the best telescopic views of the ringed planet and moons
Friday, April 13, 2012
A Dust Devil of Mars
Labels: Astronomy Picture, Astronomy picture of the day
It was late in the northern martian spring
when the HiRISE camera onboard the Mars Reconnaissance Orbiter
spied
this local denizen.
Tracking south and east (down and right)
across the flat, dust-covered
Amazonis Planitia
the core of the
whirling dust devil is about 30 meters in diameter.
Lofting dust into the thin
martian
atmosphere, its plume
reaches more than 800 meters above the surface.
Not following the path of the dust devil, the plume is blown toward
the east by a westerly breeze.
Common in this region,
dust devils occur as the surface is heated by the Sun,
generating warm, rising air currents that begin to rotate.
Tangential
wind speeds of up to 110 kilometers per hour are reported
for
dust devils in other HiRISE images.
Thursday, April 12, 2012
Yuri's Planet
Labels: Astronomy Picture, Astronomy picture of the day
On another April 12th,
in 1961, Soviet cosmonaut Yuri Alexseyevich Gagarin
became the first human
to see planet Earth from space.
Commenting on his
view from orbit
he reported, "The sky is very dark; the Earth is bluish.
Everything is seen very clearly".
To celebrate, consider this recent image from the orbiting
International Space Station.
A stunning view of the planet at night
from an altitude of 240 miles, it was recorded on March 28.
The lights of Moscow, Russia are near picture center
and one of the station's solar panel arrays is on the left.
Aurora and the glare of sunlight lie
along the planet's gently curving horizon.
Stars above the horizon include the compact
Pleiades star cluster,
immersed in the auroral glow.
Wednesday, April 11, 2012
Geostationary Satellites Beyond the Alps
Labels: Astronomy Picture, Astronomy picture of the day
Why don't those stars move?
Stars in the sky will typically appear to rise and
set as the Earth turns.
Those far to the north or south will appear to
circle the pole.
If you look closely at the
above time-lapse movie,
however, there are points of light that appear
stationary.
These objects are not stars but
human-launched robotic spacecraft that remain fixed high above the
Earth's equator.
Called geostationary satellites, they don't fall down because they do orbit the Earth -- they just orbit at exactly the same speed that the
Earth rotates.
The orbital distance where this is possible is much farther than the
International Space Station but much closer than the Moon.
The video was taken from one of the
highest
revolving restaurants in the world located on the
Mittelallalin
in the Swiss
Alps.
In the foreground is a mountain known as the
Allalinhorn.
An even closer inspection will show that the
geostationary satellites flash with
glints of reflected sunlight.
The satellites also all appear on a single line --
actually the projection of the Earth's equator onto the sky.
Tuesday, April 10, 2012
A Fox Fur, a Unicorn, and a Christmas Tree
Labels: Astronomy Picture, Astronomy picture of the day
What do the following things have in common: a cone, the fur of a fox, and a Christmas tree?
Answer: they all occur in the constellation of the unicorn
(Monoceros).
Pictured above as a star forming region
cataloged as NGC 2264, the complex jumble of
cosmic gas and dust is about 2,700 light-years distant and
mixes reddish emission nebulae
excited by energetic light from
newborn stars with dark
interstellar dust clouds.
Where the otherwise obscuring dust clouds lie close
to the hot, young stars they also reflect starlight, forming blue
reflection nebulae.
The above image spans about 3/4 degree or nearly 1.5 full moons,
covering 40 light-years at the distance of NGC 2264.
Its cast of cosmic characters includes
the Fox Fur Nebula, whose
convoluted pelt lies below center, bright
variable star
S Mon immersed in the blue-tinted haze, and the
Cone Nebula near the tree's top.
Of course, the stars of NGC 2264 are also known as the
Christmas Tree
star cluster.
The triangular tree shape traced by the stars appears sideways here,
with its apex at the Cone Nebula and its broader base
centered near S Mon.
Monday, April 9, 2012
Blue Straggler Stars in Globular Cluster M53
Labels: Astronomy Picture, Astronomy picture of the day
If our Sun were part of M53, the
night sky would glow like a jewel box of bright stars.
M53, also known as NGC 5024, is one of about 250
globular clusters that survive in our Galaxy.
Most of the stars in
M53
are older and redder than our Sun, but some enigmatic stars appear to be bluer and younger.
These young
stars might contradict the hypothesis that all the stars in
M53 formed at nearly the same time.
These unusual stars are known as
blue stragglers
and are unusually common in M53.
After much debate, blue stragglers are now thought to be stars
rejuvenated by fresh matter falling in from a binary star companion.
By analyzing pictures of globular clusters like the
above image taken by the Hubble Space Telescope, astronomers
use the abundance of stars like
blue stragglers to help
determine the age of the globular cluster and hence a limit on the age of the universe.
M53, visible with a binoculars towards the
constellation of Bernice's Hair (Coma Berenices),
contains over 250,000 stars and is one of the furthest
globulars from the center of our Galaxy.
Sunday, April 8, 2012
Io: Moon Over Jupiter
Labels: Astronomy Picture, Astronomy picture of the day
How big is Jupiter's moon Io?
The most volcanic body in the Solar System,
Io (usually pronounced "EYE-oh") is
3,600 kilometers in diameter, about the size of
planet Earth's single large
natural satellite.
Gliding
past Jupiter
at the turn of the millennium, the Cassini spacecraft captured this
awe
inspiring view of active Io
with the
largest gas giant as a backdrop,
offering a stunning demonstration of the ruling planet's
relative size.
Although in the above picture Io appears
to be located just in front of the
swirling Jovian clouds,
Io hurtles around its orbit once every 42 hours
at a distance of 420,000 kilometers or so from the center
of Jupiter.
That puts
Io
nearly 350,000 kilometers above
Jupiter's cloud tops,
roughly equivalent to the distance between
Earth and Moon.
The
Cassini
spacecraft itself was about 10 million kilometers
from Jupiter when recording the image data.
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