juliensimon/nasa-apod huggingface dataset:
North America and the Pelican (2010-12-18)

Here lie familiar shapes in unfamiliar locations. On the left is an emission nebula cataloged as NGC 7000, famous partly because it resembles our fair planet's continent of North America.  The emission region to the right of the North America Nebula is IC 5070, also known for its suggestive outlines as the Pelican Nebula.  Separated by a dark cloud of obscuring dust, the two bright nebulae are about 1,500 light-years away. At that distance, the 4 degree wide field of view spans 100 light-years. This spectacular cosmic portrait combines narrow band images of the region in a false-color palette to highlight bright ionization fronts with fine details of dark, dusty forms in silhouette. Emission from atomic hydrogen, sulfur, and oxygen is captured in the narrow band data. These nebulae can be seen with binoculars from a dark location.  Look northeast of bright star Deneb in the constellation Cygnus the Swan.

Image credit: Martin Pugh
M82: Galaxy with a Supergalactic Wind (2010-12-19)

What's lighting up the Cigar Galaxy?  M82, as this irregular galaxy is also known, was stirred up by a recent pass near large spiral galaxy M81.  This doesn't fully explain the source of the red-glowing outwardly expanding gas, however.  Recent evidence indicates that this gas is being driven out by the combined emerging particle winds of many stars, together creating a galactic superwind..  The above photographic mosaic highlights a specific color of red light strongly emitted by ionized hydrogen gas, showing detailed filaments of this gas.  The filaments extend for over 10,000 light years. The 12-million light-year distant Cigar Galaxy is the brightest galaxy in the sky in infrared light, and can be seen in visible light with a small telescope towards the constellation of the Great Bear (Ursa Major).   Best Astronomy Images: APOD Editor to speak in Philadelphia on Jan 5 and New York City on Jan 7
A Lunar Eclipse on Solstice Day (2010-12-20)

Sometime after sunset tonight, the Moon will go dark. This total lunar eclipse, where the entire Moon is engulfed in the shadow of the Earth, will be visible from all of North America, while the partial phase of this eclipse will be visible throughout much of the rest of the world.  Observers on North America's east coast will have to wait until after midnight for totality to begin, while west coasters should be able to see a fully darkened moon before midnight. Pictured above is a digital prediction, in image form, for how the Moon and the surrounding sky could appear near maximum darkness. Rolling your cursor over the image will bring up labels. Parts of the Moon entering the circle labeled umbra will appear the darkest since the Sun there will be completely blocked by the Earth.  Parts of the Moon entering the circle labeled penumbra will be exposed to some direct sunlight, and so shine by some degree by reflected light. The diminished glare of the normally full Moon will allow unusually good viewings of nearby celestial wonders such as the supernova remnant Simeis 147, the open star cluster M35, and the Crab Nebula M1.  By coincidence this eclipse occurs on the day with the shortest amount of daylight in the northern hemisphere -- the Winter Solstice. This solstice eclipse is the first in 456 years, although so far it appears that no one has figured out when the next solstice eclipse will be.

Image credit: Jerry Lodriguss
(Catching the Light)
Tyrrhenian Sea and Solstice Sky (2010-12-21)

Today the solstice occurs at 23:38 Universal Time, the Sun reaching its southernmost declination in planet Earth's sky. Of course, the December solstice marks the beginning of winter in the northern hemisphere and summer in the south. When viewed from northern latitudes, and as shown in the above horizontally compressed image, the Sun will make its lowest arc through the sky along the southern horizon. So in the north, the solstice day has the shortest length of time between sunrise and sunset and fewest hours of daylight.  This striking composite image follows the Sun's path through the December solstice day of 2005 in a beautiful blue sky, looking down the Tyrrhenian Sea coast from Santa Severa toward Fiumicino, Italy. The view covers about 115 degrees in 43 separate, well-planned exposures from sunrise to sunset.   Browse: Lunar eclipse images from last night  Best Astronomy Images: APOD Editor to speak in Philadelphia on Jan 5 and New York City on Jan 7

Image credit: Danilo Pivato
Hidden Galaxy IC 342 (2010-12-22)

Similar in size to other large, bright spiral galaxies, IC 342 is a mere 7 million light-years distant in the long-necked, northern constellation Camelopardalis. A sprawling island universe, IC 342 would otherwise be a prominent galaxy in our night sky, but it is almost hidden from view behind the veil of stars, gas and dust clouds in the plane of our Milky Way galaxy. Even though IC 342's light is dimmed by intervening cosmic clouds, this remarkably sharp telescopic image traces the galaxy's own obscuring dust, blue star clusters, and glowing pink star forming regions along spiral arms that Wind far from the galaxy's core. IC 342 may have undergone a recent burst of star formation activity and is close enough to have gravitationally influenced the evolution of the local group of galaxies and the Milky Way.

Image credit: Hay Creek Observatory
The Solstice Moon's Eclipse (2010-12-23)

A big, bright, beautiful Full Moon slid into planet Earth's shadow early Tuesday morning. Remarkably, the total lunar eclipse coincided with the date of the December Solstice. During the eclipse, the best viewing in North America found the coppery lunar disc high in a cold winter sky, the Moon reddened by light filtering into the Earth's dark central shadow or umbra. The light comes from all the sunsets and sunrises, seen from a lunar perspective around the edges of a silhouetted Earth. Passing closer to the center of the umbra, the Moon's southern hemisphere (left) appears darker in this eclipse image, recorded from Deerlick Astronomy Village, Georgia, USA. The picture is a digital composite, a separate longer exposure added to an eclipse frame to capture the surrounding star field.

Image credit: Chris Hetlage
Star Trails in the North (2010-12-24)

Pointing skyward, the wall of this ruined Viking church still stands after a thousand winters, near the town of Vallentuna, Sweden. The time exposure records the scene on December 14th as stars leave graceful arcing trails during a long night, reflecting planet Earth's daily rotation on its axis. The Earth's axis points toward Polaris, the North Star, near the center of the concentric trails. Welcomed by skygazers on this winter's night, a bright meteor from the annual Geminid meteor shower also flashes through the frame. The meteor cuts across the star trails just above the lower church wall. Contributing to the beautiful composition, meteor streak and church apex both gesture toward the North Celestial Pole.

Image credit: Clear Skies
Decorating the Sky (2010-12-25)

Bright stars, clouds of dust and glowing nebulae decorate this cosmic scene, a skyscape just north of Orion's belt. Close to the plane of our Milky Way Galaxy, the wide field view spans about 5.5 degrees. Striking bluish M78, a reflection nebula, is at the left. M78's tint is due to dust preferentially reflecting the blue light of hot, young stars. In colorful contrast, the red sash of glowing hydrogen gas sweeping through the center is part of the region's faint but extensive emission nebula known as Barnard's Loop. At right, a dark dust cloud forms a prominent silhouette cataloged as LDN 1622. While M78 and the complex Barnard's Loop are some 1,500 light-years away, LDN 1622 is likely to be much closer, only about 500 light-years distant from our fair planet Earth.

Image credit: Rogelio
Bernal Andreo
Sideways Orion Over Snowy Ireland (2010-12-26)

Orion always comes up sideways ... and was caught in the act earlier this month by over a snowy landscape in Donegal, Ireland. To compose this serene picture, the photographer found a picturesque setting to the east, waited until after sunset, and then momentarily lit the foreground with a flashlight. The three bright stars in Orion's belt stand in a nearly vertical line above the snow covered road at the bottom. Hanging from his belt, the stars and nebulae of the Hunter's sword are visible lower and to the right. Yellow-orange Betelgeuse is the brightest star on the image left. As winter progresses in Earth's northern hemisphere, Orion will rise earlier and so appear continually higher in the sky at sunset.    Best Astronomy Images: APOD Editor to speak in Philadelphia on Jan 5 and New York City on Jan 7

Image credit: Brendan Alexander 
(Donegal Skies)
One Million Galaxies (2010-12-27)

Are the nearest galaxies distributed randomly? A plot of over one million of the brightest "extended sources" detected by the Two Micron All Sky Survey (2MASS) shows that they are not.  The vast majority of these infrared extended sources are galaxies.  Visible above is an incredible tapestry of structure that provides limits on how the universe formed and evolved.  Many galaxies are gravitationally bound together to form clusters, which themselves are loosely bound into superclusters, which in turn are sometimes seen to align over even larger scale structures.  In contrast, very bright stars inside our own Milky Way Galaxy cause the vertical blue sash.
Skylights Over Libya (2010-12-28)

Sometimes the sky itself seems to glow.  Usually, this means you are seeing a cloud reflecting sunlight or moonlight.  If the glow appears as a faint band of light running across the whole sky, you are probably seeing the combined light from the billions of stars that compose our Milky Way Galaxy.  Such a glow is visible rising diagonally up to the right in the above image. If the glow is seen coming up from the horizon just before sunrise or just after sunset, however, you might be seeing something called zodiacal light.  Pictured rising diagonally up to the left in the above image, zodiacal light is just sunlight reflected by tiny dust particles orbiting in our Solar System.  Many of these particles were ejected by comets. The above image was taken just after sunset earlier this month from Ras Lanuf, Libya.   Best Astronomy Images: APOD Editor to speak in Philadelphia on Jan 5 and New York City on Jan 7

Image credit: Tunç Tezel
Eclipse at Moonset (2010-12-29)

Hugging the horizon, a dark red Moon greeted early morning skygazers in eastern Atlantic regions on December 21, as the total phase of 2010's Solstice Lunar Eclipse began near moonset. This well composed image of the geocentric celestial event is a composite of multiple exposures following the progression of the eclipse from Tenerife, Canary Islands. Initially reflecting brightly on a sea of clouds and the ocean's surface itself, the Moon sinks deeper into eclipse as it moves from left to right across the sky. Opposite the Sun, the Moon was immersed in the darkest part of Earth's shadow as it approached the western horizon, just before sunrise came to Tenerife.

Image credit: Grupo de Observadores
Astronómicos de Tenerife
Still Life with NGC 2170 (2010-12-30)

In this beautiful celestial still life composed with a cosmic brush, dusty nebula NGC 2170 shines at the upper left. Reflecting the light of nearby hot stars, NGC 2170 is joined by other bluish reflection nebulae, a compact red emission region, and streamers of obscuring dust against a backdrop of stars. Like the common household items still life painters often choose for their subjects, the clouds of gas, dust, and hot stars pictured here are also commonly found in this setting - a massive, star-forming molecular cloud in the constellation Monoceros. The giant molecular cloud, Mon R2, is impressively close, estimated to be only 2,400 light-years or so away. At that distance, this canvas would be about 15 light-years across.

Image credit: Adam Block
Analemma 2010 (2010-12-31)

Looking back on the year, have you wondered where the Sun was in the sky each day during 2010 at exacty 9am UT? Of course you have. Search no further for the answer! It was somewhere along this celestial figure 8 curve known as an analemma. Recorded from a residential backyard in the small town of Veszprem, Hungary, this composite analemma image consists of 36 separate exposures of the Sun made at 9:00 UT, spaced throughout the year, plus a background image made without a solar filter. The background image was taken on the sunny afternoon of October 9 (13:45 UT). On the left is the photographer's shadow. The positions of the Sun at the 2010 solstice dates are at the upper (June 21) and lower (December 21) extremes of the analemma curve. On the equinox dates (March 20, September 23) the Sun was along the curve half way between the solstices. The tilt of planet Earth's axis and the variation in speed as it moves around its elliptical orbit combine to produce the graceful analemma curve.

Image credit: Tamas Ladanyi
Fireworks Galaxy NGC 6946 (2011-01-01)

Celebrate the New Year with the Fireworks Galaxy! Also known as NGC 6946, the big, beautiful spiral galaxy is located just 10 million light-years away, behind a veil of foreground dust and stars in the high and far-off constellation of Cepheus. From our vantage point in the Milky Way Galaxy, we see NGC 6946 face-on. In this colorful cosmic portrait, the galaxy's colors change from the yellowish light of old stars in the core to young blue star clusters and reddish star forming regions along the loose, fragmented spiral arms. NGC 6946 is bright in infrared light and rich in gas and dust, exhibiting a furious rate of star formation. Nearly 40,000 light-years across, the nearby spiral is fittingly referred to as the Fireworks Galaxy. Over the last 100 years, at least nine supernovae, the death explosions of massive stars, were discovered in NGC 6946. By comparison, the average rate for supernovae in the Milky Way is about 1 per century.

Image credit: Adam Block
Looking Back at an Eclipsed Earth (2011-01-02)

Here is what the Earth looks like during a solar eclipse. The shadow of the Moon can be seen darkening part of Earth. This shadow moved across the Earth at nearly 2000 kilometers per hour. Only observers near the center of the dark circle see a total solar eclipse - others see a partial eclipse where only part of the Sun appears blocked by the Moon. This spectacular picture of the 1999 August 11 solar eclipse was one of the last ever taken from the Mir space station. The two bright spots that appear on the upper left are thought to be Jupiter and Saturn. Mir was deorbited in a controlled re-entry in 2001.

Image credit: CNES
Winter Hexagon Over Stagecoach Colorado (2011-01-03)

If you can find Orion, you might be able to find the Winter Hexagon.  The Winter Hexagon involves some of the brightest stars visible, together forming a large and easily found pattern in the winter sky of Earth's northern hemisphere.  The stars involved can usually be identified even in the bright night skies of a big city, although here they appear over darker Stagecoach, Colorado, USA..  The six stars that compose the Winter Hexagon are Aldebaran, Capella, Castor (and Pollux), Procyon, Rigel, and Sirius.  Here, the band of our Milky Way Galaxy runs through the center of the Winter Hexagon, while the Pleiades open star cluster is visible just above. The Winter Hexagon asterism engulfs several constellations including much of the iconic steppingstone Orion.   Best Astronomy Images: APOD Editor to speak in Philadelphia and New York City this week

Image credit: Jimmy Westlake
(Colorado Mountain College)
A Green Flash from the Sun (2011-01-04)

Many think it is just a myth.  Others think it is true but its cause isn't known.  Adventurers pride themselves on having seen it.  It's a green flash from the Sun.  The truth is the green flash does exist and its cause is well understood.  Just as the setting Sun disappears completely from view, a last glimmer appears startlingly green.  The effect is typically visible only from locations with a low, distant horizon, and lasts just a few seconds. A green flash is also visible for a rising Sun, but takes better timing to spot.  A dramatic green flash, as well as an even more rare blue flash, was caught in the above photograph recently observed during a sunset visible from Teide Observatory at Tenerife, Cannary Islands, Spain.  The Sun itself does not turn partly green or blue -- the effect is caused by layers of the Earth's atmosphere acting like a prism.   Best Astronomy Images: APOD Editor to speak in Philadelphia tomorrow night and NYC Friday

Image credit: Juan Jos� Manzano
(Grupo de Observadores
Astron�micos de Tenerife)
Eclipsing the Sun (2011-01-05)

Skywatchers throughout much of Europe, North Africa, and Central Asia, were treated to the first eclipse of the new year on January 4, a partial eclipse of the Sun. But traveling to the area around Muscat, capital city of Oman, photographer Thierry Legault planned to simultaneously record two eclipses on that date, calculating from that position, for a brief moment, both the Moon and the International Space Station could be seen in silhouette, crossing the Sun. His sharp, 1/5000th second exposure is shown here, capturing planet Earth's two largest satellites against the bright solar disk. As the partial solar eclipse unfolded, the space station (above and left of center) zipped across the scene in less than 1 second, about 500 kilometers from the photographer's telescope and camera. Of course, the Moon was 400 thousand kilometers away. Complete with sunspots, the Sun was 150 million kilometers distant.   Best Astronomy Images: APOD Editor to speak in Philadelphia tonight and NYC Friday

Image credit: Thierry Legault
Sunrise, Moonrise (2011-01-06)

For many Europeans, the Sun and New Moon rose together on January 4 in a partial solar eclipse. Arriving close on the heels of the new year, it was the first of a series of four(!) partial solar eclipses due in 2011. This composite image documents the graceful celestial event in colorful morning skies over Graz, Austria. Beginning before sunrise, frames were taken to record the position and progress of the eclipse every 15 minutes. As Sun and Moon rose above the eastern horizon, the town of Graz is seen bathed in warming sunlight only partially blocked by the New Moon, spreading beneath the town's landmark clock tower.   Best Astronomy Images: APOD Editor to speak in NYC Friday

Image credit: Robert Pölzl
Sunset, Moonset (2011-01-07)

Seen from central and northern Asia, the Sun and New Moon set together on January 4, in a partial solar eclipse. Close to its maximum phase, the eclipse is captured near the moment of sunset in this wintry scene from the bank of the Berd River near Novosibirsk, Siberia, Russia. An evocative view in fading light, the picture looks toward the western horizon across a snowy, frozen landscape. Along with offset Sun and Moon, the dimly lit sky includes an industrial smoke plume and airplane contrail.   Best Astronomy Images: APOD Editor to speak in NYC tonight.

Image credit: Aleksandr Yuferev
NGC 7293: The Helix Nebula (2011-01-08)

A mere seven hundred light years from Earth, in the constellation Aquarius, a sun-like star is dying. Its last few thousand years have produced the Helix Nebula (NGC 7293), a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution.  A total of 10 hours of exposure time have gone in to creating this remarkably deep view of the nebula. It shows details of the Helix's brighter inner region, about 3 light-years across, but also follows fainter outer halo features that give the nebula a span of well over six light-years. The white dot at the Helix's center is this Planetary Nebula's hot, central star. A simple looking nebula at first glance, the Helix is now understood to have a surprisingly complex geometry.

Image credit: Hay Creek Observatory
The Antikythera Mechanism (2011-01-09)

What is it?  It was found at the bottom of the sea aboard an ancient Greek ship.  Its seeming complexity has prompted decades of study, although some of its functions remained unknown.  Recent X-rays of the device have now confirmed the nature of the Antikythera mechanism, and discovered several surprising functions.  The Antikythera mechanism has been discovered to be a mechanical computer of an accuracy thought impossible in 80 BC, when the ship that carried it sank.   Such sophisticated technology was not thought to be developed by humanity for another 1,000 years. Its wheels and gears create a portable orrery of the sky that predicted star and planet locations as well as lunar and solar eclipses. The Antikythera mechanism, shown above, is 33 centimeters high and similar in size to a large book.

Image credit: Wikipedia
A Sun Halo Beyond Stockholm (2011-01-10)

What's happened to the Sun?  Sometimes it looks like the Sun is being viewed through a large lens.  In the above case, however, there are actually millions of lenses: ice crystals.  As water freezes in the upper atmosphere, small, flat, six-sided, ice crystals might be formed.  As these crystals flutter to the ground, much time is spent with their faces flat, parallel to the ground.  An observer may pass through the same plane as many of the falling ice crystals near sunrise or sunset.  During this alignment, each crystal can act like a miniature lens, refracting sunlight into our view and creating phenomena like parhelia, the technical term for sundogs.  The above image was taken  last year in  Stockholm, Sweden. Visible in the image center is the Sun, while two bright sundogs glow prominently from both the left and the right.  Also visible is the bright 22 degree halo -- as well as the rarer and much fainter 46 degree halo -- also created by sunlight reflecting off of atmospheric ice crystals.

Image credit: Peter Ros�n
The Cosmic Web of the Tarantula Nebula (2011-01-11)

It is the largest and most complex star forming region in the entire galactic neighborhood. Located in the Large Magellanic Cloud, a small satellite galaxy orbiting our Milky Way galaxy, the region's spidery appearance is responsible for its popular name, the Tarantula nebula. This tarantula, however, is about 1,000 light-years across. Were it placed at the distance of Milky Way's Orion Nebula, only 1,500 light-years distant and the nearest stellar nursery to Earth, it would appear to cover about 30 degrees (60 full moons) on the sky. Intriguing details of the nebula are visible in the above image shown in scientific colors. The spindly arms of the Tarantula nebula surround NGC 2070, a star cluster that contains some of the brightest, most massive stars known, visible in blue on the right. Since massive stars live fast and die young, it is not so surprising that the cosmic Tarantula also lies near the site of the closest recent supernova.

Image credit: Marcelo Salemme
The Seagull Nebula (2011-01-12)

This broad expanse of glowing gas and dust presents a bird-like visage to astronomers from planet Earth, suggesting its popular moniker - The Seagull Nebula. This portrait of the cosmic bird covers a 1.6 degree wide swath across the plane of the Milky Way, near the direction of Sirius, alpha star of the constellation Canis Major. Of course, the region includes objects with other catalog designations: notably NGC 2327, a compact, dusty emission region with an embedded massive star that forms the bird's head (aka the Parrot Nebula, above center). IC 2177 forms the sweeping arc of the seagull's wings. Dominated by the reddish glow of atomic hydrogen, the complex of gas and dust clouds with bright young stars spans over 100 light-years at an estimated 3,800 light-year distance.

Image credit: Michael Sidonio