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Astronomy Picture of the Day |
APOD: 2011 October 27 - Young Suns of NGC 7129
Explanation:
Young suns still lie
within dusty NGC 7129, some
3,000 light-years away toward the royal
constellation
Cepheus.
While these stars
are at a relatively tender age, only a few million years old, it is
likely that our own Sun formed in a similar stellar nursery some
five billion years ago.
Most noticeable in
the sharp image are the
lovely bluish dust clouds
that reflect the youthful starlight.
But the compact, deep red crescent shapes are also markers
of energetic, young stellar objects.
Known as
Herbig-Haro
objects, their shape and color is
characteristic of glowing hydrogen gas
shocked by
jets streaming away from newborn stars.
Paler, extended filaments of
redish emission
mingling with the bluish
clouds are caused by dust grains effectively converting the
invisible ultraviolet starlight to visible red light through
photoluminesence.
Ultimately the natal gas and dust in the region
will be dispersed, the
stars
drifting apart as the loose
cluster orbits the center of the Galaxy.
At the estimated distance of
NGC 7129, this telescopic view spans
about 40 light-years.
APOD: 2009 March 7 - Comet Lulin and Distant Galaxies
Explanation:
Now fading in our night sky, Comet Lulin
has provided some lovely
cosmic
vistas.
Moving rapidly against the
background of stars, Lulin briefly
posed with the likes
of Saturn, and
Regulus (Alpha Leo).
But here it is seen against a field of distant galaxies.
To reveal the faint
background galaxies and trace the
comet's fading tail,
the remarkable picture is a blended composite
of telescopic exposures aligned with the both the stars and
the
speedy comet.
The largest galaxies seen left of the comet's head
or coma are
cataloged as NGC 3016, NGC 3019, NGC 3020 and NGC 3024 and lie
at a distance of 100 million light-years or so.
When the exposures were made, on February 28,
the comet was about 3.6
light-minutes
from Earth.
APOD: 2009 January 9 - NGC 4945 in Centaurus
Explanation:
Large, dusty, spiral galaxy NGC 4945 is seen
edge-on
near the center of this
rich
telescopic image.
The field of view spans nearly 2 degrees, or about 4 times the width
of the Full Moon, toward the
expansive southern
constellation Centaurus.
About 13 million light-years distant, NGC 4945 is almost
the size of our own
Milky Way Galaxy.
But X-ray and infrared observations
reveal
even more high energy emission and star formation in the core
of NGC 4945.
The other prominent galaxy in the field, NGC 4976, is an
elliptical galaxy.
Left of center,
NGC 4976
is much farther away, at a distance of about 35 million light-years,
and not physically associated with NGC 4945.
APOD: 2008 December 4 - Venus in the Moon
Explanation:
On December 1, bright planets Venus and Jupiter gathered near the
young crescent Moon, an inspiring
celestial scene
in early evening skies
around
the world.
But from
some locations
the Moon actually passed in front of Venus,
interrupting the tight grouping with a lunar occultation.
Captured from Wildon, Austria,
this twilight view shows the
silvery evening star about five minutes before it
slipped behind
the dark lunar limb and vanished from sight for more than hour.
The image is a combination of long and short exposures showing
details of the lunar surface illuminated by both faint
earthshine
and bright sunlight.
In the inset, recorded later in darkened
skies over Breil-sur-Roya in
southeastern France, a dazzling Venus has reappeared below the
bright lunar crescent.
Of course, Jupiter, at the upper right about 2 degrees from
Venus and Moon, is
sporting moons of its own seen as
tiny pinpricks of light on either side of the bright planet.
APOD: 2008 October 9 - Massive Stars in NGC 6357
Explanation:
Massive stars lie
within NGC 6357,
an expansive emission nebula complex
some 8,000 light-years away in the tail of the constellation
Scorpius.
In fact, positioned just below center in
this close-up view of
NGC 6357, star cluster Pismis 24 includes
some of the most massive stars known
in the galaxy,
stars with over 100 times the mass of the Sun.
The nebula's bright central region also contains dusty pillars of
molecular gas, likely hiding massive protostars from the
prying eyes
of optical instruments.
Intricate shapes in the nebula are carved by interstellar winds
and energetic radiation from the young and newly forming
massive stars.
This alluring telescopic view spans just under 50 light-years at
the estimated distance of NGC 6357.
APOD: 2008 July 19 - M16 and the Eagle Nebula
Explanation:
Young star cluster
M16 is
surrounded by natal clouds of cosmic
dust and glowing gas also known as The Eagle Nebula.
This beautifully
detailed image of the region includes
fantastic
shapes made famous in
well-known Hubble Space
Telescope close-ups of the starforming complex.
Described as elephant trunks or
Pillars of Creation, dense,
dusty columns rising near the center are light-years in length but
are gravitationally contracting
to
form stars.
Energetic radiation from the cluster stars erodes material near
the tips, eventually exposing the embedded new stars.
Extending from the upper left edge of the nebula is another dusty
starforming column known as the
Fairy of Eagle Nebula.
M16 and the Eagle Nebula lie about 7,000 light-years away,
an easy target for binoculars or small telescopes in a
nebula rich part of the sky
toward the split constellation
Serpens Cauda
(the tail of the snake).
APOD: 2008 April 3 - South of Orion
Explanation:
This tantalizing array of nebulae and stars can be found
about 2 degrees south of the famous
star-forming Orion Nebula.
The
region abounds with energetic young stars producing jets and
outflows that push through the surrounding
material at speeds of hundreds of kilometers per second.
The interaction creates luminous shock
waves known as
Herbig-Haro (HH) objects.
For example, the graceful, flowing arc just right of center
is cataloged as HH 222, also called the Waterfall Nebula.
Seen below the Waterfall, HH 401 has a distinctive cone shape.
The bright bluish nebula below and left of center
is NGC 1999, a dusty cloud reflecting
light from an embedded variable star.
The entire cosmic vista
spans over 30 light-years, near the edge of the
Orion
molecular cloud
complex
some 1,500 light-years distant.
APOD: 2008 March 29 - Spiral Galaxy NGC 2841
Explanation:
Some 50 million light-years distant, spiral galaxy NGC 2841
can be found in the northern constellation of
Ursa Major.
This sharp view of the
gorgeous island universe
shows off a striking yellow nucleus and galactic disk with tightly
wound
spiral arms.
NGC 2841 has a diameter of over 150,000 light-years, even larger than
our own
Milky Way Galaxy.
The galaxy's dust lanes and turbulent star-forming regions are found
along the spiral arms, but
X-ray images
suggest that resulting winds and stellar explosions create
plumes of hot gas extending into a halo around NGC 2841.
Of course, the prominent stars with a
spiky appearance in
the picture are close foreground objects within the Milky Way
and not associated with
NGC 2841.
APOD: 2007 September 6 - Time Tunnel
Explanation:
Spiky stars are nearby, but
fuzzy galaxies are strewn far across
the Universe in this cosmic view.
Spanning about 1/2 degree on the sky,
the pretty picture is the result of astronomer Johannes
Schedler's project to look back in time,
toward a quasar 12.7
billion light-years away.
The quasar is just visible in the
full resolution image at the
position marked by short vertical lines (center).
The intrinsically bright nucleus of a young,
active galaxy powered by a supermassive black hole, the quasar
was recently identified
as one of the most distant
objects known.
Since
light
travels at a finite speed, the
galaxies receding into the distance are seen as they
were in the increasingly remote past.
The quasar appears as it did about 12.7 billion years ago,
when the Universe was just 7 percent of its
present age.
Of course,
the
expansion of the Universe
has redshifted the light.
Schedler added image data extending to the near-infrared,
acquired by collaborator Ken Crawford,
to detect the distant quasar, with a measured
redshift of 6.04.
APOD: 2007 June 29 - Cat's Eye Wide and Deep
Explanation:
The Cat's Eye Nebula
(NGC 6543) is one of the best known
planetary
nebulae in the sky.
Its more familiar outlines are seen in the brighter central region of
this impressive wide-angle view.
But the composite image also combines many
short and long exposures to reveal the nebula's
extremely faint halo.
At an estimated distance of 3,000 light-years, the
faint outer halo is over 5 light-years across.
Planetary
nebulae have long been appreciated as a final phase
in the life of a sun-like star.
More recently, some planetary nebulae are
found to have
halos like this one, likely formed of material shrugged off during
earlier episodes in the star's evolution.
While the planetary
nebula phase is thought to last for around 10,000 years,
astronomers estimate the age of the outer filamentary portions
of this halo to be 50,000 to 90,000 years.
Visible on the right, some 50 million light-years beyond
the Cat's Eye, lies spiral galaxy
NGC 6552.
APOD: 2007 March 8 - Eclipsed Moon and Stars
Explanation:
This dramatic image
features a dark red Moon during a total lunar eclipse -- celestial
shadow play enjoyed by
many
denizens of planet Earth last Saturday.
Recorded near Wildon, Austria, the picture is a composite
of two exposures; a relatively short exposure to feature
the lunar surface and a longer exposure to capture background
stars in the
constellation
Leo.
Completely immersed in Earth's cone-shaped shadow during the
total eclipse
phase, the lunar surface is still illuminated by
sunlight, reddened and
refracted into the dark shadow region
by a dusty atmosphere.
As a result, familiar details
of the Moon's nearside are easy
to pick out, including
the smooth lunar mare and the large ray
crater Tycho.
In this telescopic view, the background stars
are faint and most would be invisible to the naked eye.
APOD: 2006 September 8 - Messier 110
Explanation:
This very sharp
telescopic vista features
the last object in the modern version of Charles
Messier's catalog
of bright clusters and nebulae -
Messier 110.
A dwarf elliptical galaxy,
M110 (aka NGC 205) is actually a
bright satellite of the
large spiral galaxy
Andromeda,
making M110 a fellow member
of the local
group of galaxies.
Seen through a foreground of nearby stars,
M110 is about 15,000 light-years across.
That makes it comparable
in size to satellite galaxies of our own Milky Way,
the Large and
Small Magellanic Clouds.
Though elliptical galaxies
are normally thought to be lacking in gas and dust to form new stars,
M110 is known to contain
young stars, and faint dust clouds
can easily be seen in this detailed image at about the
7 and 11 o'clock positions relative to the galaxy center.
APOD: 2006 June 23 - East of Antares
Explanation:
East of Antares, dark markings seem
to sprawl through the crowded star fields
toward the center of our Milky Way Galaxy.
Cataloged in the early 20th
century by astronomer
E. E. Barnard, the obscuring
interstellar dust clouds
include
B72,
B77, B78, and B59, seen in silhouette
against the starry background.
Here, their combined shape suggests smoke rising from
a pipe, and so the dark nebula's popular name is the Pipe Nebula.
This gorgeous
and expansive view was recorded in
very dark skies over
Hakos,
Namibia.
It covers a full 10 by 7 degree field in the
pronounceable
constellation Ophiuchus.
APOD: 2006 April 15 - Galaxy Wars: M81 versus M82
Explanation:
In this stunning cosmic vista,
galaxy M81 is on the left surrounded by blue spiral arms.
On the right marked by massive gas and dust clouds,
is M82.
These two mammoth galaxies have been locked in
gravitational combat
for the past billion years.
The gravity from each galaxy
dramatically affects the
other during each hundred million-year pass.
Last go-round, M82's gravity likely raised
density waves rippling around M81, resulting in the richness of
M81's
spiral arms.
But M81 left
M82 with
violent star forming regions and
colliding gas clouds so energetic the galaxy
glows
in X-rays.
In a few billion years only one galaxy
will remain.
APOD: 2006 February 16 - The Color of the Moon
Explanation:
Earth's Moon
is normally seen in subtle shades of grey or yellow.
But small color differences
have been greatly exaggerated
to make this dramatic mosaic image of
the Moon's gibbous phase.
The familiar Sea of Tranquility
(Mare Tranquillitatis) is the blue area right
of center.
White lines radiate
from the crater Tycho at bottom left,
while purplish tones mottle the crater
Copernicus left of center.
Though exaggerated, the different colors are recognized to
correspond to real differences in
the chemical makeup of the lunar surface - blue
hues reveal
titanium rich
areas while orange and purple colors
show regions relatively poor in titanium and iron.
Calibrated by
rock samples
from the Apollo missions, similar multicolor
images from spacecraft
have been used to explore
the Moon's
global surface composition.
APOD: 2005 June 7 - Galaxies in View
Explanation:
Galaxies abound in
this cosmic scene, a well chosen telescopic
view toward the northern constellation of
Ursa
Major.
Most noticeable are the striking pair of
spiral
galaxies -
NGC 3718
(above, right) and NGC 3729 (below center) - a mere
52 million light-years distant.
In particular, NGC 3718 has dramatic
dust lanes sweeping through
its bright central region and extensive but faint spiral arms.
Seen about 150 thousand light-years apart,
these two galaxies are likely
interacting gravitationally,
accounting for the warped and peculiar appearance of NGC 3718.
While a careful study of the deep image reveals a number
of fainter and more distant
background galaxies, another
remarkable galaxy grouping known as
Hickson Group 56 can
be found just to the right of NGC 3718.
Hickson
Group 56
contains five interacting galaxies and lies
over 400 million light-years away.
APOD: 2005 May 12 - Stars, Galaxies, and Comet Tempel 1
Explanation:
Faint
comet
Tempel 1 sports a fuzzy blue-tinted tail,
just right of center in this
lovely field of stars.
Recorded on May 3rd slowly sweeping through the
constellation Virgo,
periodic comet Tempel 1
orbits the Sun once every 5.5 years.
Also caught in the skyview are two galaxies
at the upper left -
NGC 4762 and NGC 4754 -
both members of the large
Virgo
Cluster of galaxies.
Classified as a
lenticular
galaxy, NGC 4762
presents an edge-on disk as a narrow gash of light
while NGC 4754 is a football-shaped
elliptical galaxy.
Similar in apparent size,
the galaxies and comet make for an intriguing
visual comparison,
but Tempel 1 is only about 3 light-minutes from planet Earth.
The two Virgo cluster galaxies are 50 million
light-years away.
NASA's
Deep Impact
spacecraft is scheduled to encounter
Tempel 1 on July 4th, launching a probe to impact
the comet's nucleus.
APOD: 2004 April 8 - Elusive Jellyfish Nebula
Explanation:
Normally faint and elusive, the Jellyfish Nebula is caught in
the net of
this spectacular wide-field telescopic view.
Flanked by two yellow-tinted stars at the foot of a
celestial
twin - Mu and
Eta
Geminorum -
the Jellyfish Nebula is the brighter arcing
ridge of emission with dangling tentacles just right of center.
Here, the cosmic jellyfish is seen to be
part of bubble-shaped
supernova remnant
IC 443, the expanding
debris cloud from an exploded star some 5,000 light-years away.
Also in view, emission nebula IC 444 nearly fills the field to
the upper left, dotted with small blue reflection nebulae.
Like its cousin in astrophysical waters, the
Crab Nebula,
IC 443 is known to harbor
a neutron star, the collapsed core of the massive star that
exploded over 30,000 years ago.
APOD: 2003 October 24 - Mars Moons
Explanation:
This year's record
close approach of Mars
inspired many
to enjoy telescopic views of the red planet.
But while Mars was so bright it was hard to miss,
spotting Mars' two diminutive moons
was still a good test for
observers with modest sized instruments.
Mars' moons were
discovered in August
of 1877 by Asaph Hall at the US Naval
Observatory using the large 26-inch
Alvan Clark refractor.
Recorded on this August 22nd, innermost
moon Phobos and outermost
moon Deimos are
seen here against the planet's glare in a digital composite image.
The picture consists of
of a long exposure capturing the faint, city-sized moons
and overexposing the planetary disk,
combined with a well exposed image of the
red planet, revealing dark markings on the
surface and the white south polar cap.
The images were
taken by astronomer Johannes Schedler
using an 11-inch Schmidt-Cassegrain telescope at his observatory
in southeastern Austria.
(Editor's note: For help finding Mars' moons,
just put your cursor over the image.)