juliensimon/nasa-apod huggingface dataset:
Eclipse over the Temple of Poseidon (2010-01-18)

What's happened to the Sun? The Moon moved to partly block the Sun for a few minutes last week as a partial solar eclipse became momentarily visible across part of planet Earth. In the above single exposure image, meticulous planning enabled careful photographers to capture the partially eclipsed Sun well posed just above the ancient ruins of the Temple of Poseidon in Sounio, Greece.  Unexpectedly, clouds covered the top of the Sun, while a flying bird was caught in flight just to the right of the eclipse.  At its fullest extent from some locations, the Moon was seen to cover the entire middle of the Sun, leaving the surrounding ring of fire of an annular solar eclipse. The next solar eclipse -- a total eclipse of the Sun -- will occur on 2010 July 11 but be visible only from a thin swath of the southern Pacific Ocean and near the very southern tip of South America.

Image credit: Chris Kotsiopoulos &
Anthony Ayiomamitis
(TWAN)
Dark Sand Cascades on Mars (2010-01-19)

They might look like trees on Mars, but they're not. Groups of dark brown streaks have been photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost. The above image was taken in 2008 April near the North Pole of Mars. At that time, dark sand on the interior of Martian sand dunes became more and more visible as the spring Sun melted the lighter carbon dioxide ice.  When occurring near the top of a dune, dark sand may cascade down the dune leaving dark surface streaks -- streaks that might appear at first to be trees standing in front of the lighter regions, but cast no shadows. Objects about 25 centimeters across are resolved on this image spanning about one kilometer. Close ups of some parts of this image show billowing plumes indicating that the sand slides were occurring even when the image was being taken.
The Known Universe (2010-01-20)

What would it look like to travel across the known universe? To help humanity visualize this, the American Museum of Natural History has produced a modern movie featuring many visual highlights of such a trip. The video starts in Earth's Himalayan Mountains and then dramatically zooms out, showing the orbits of Earth's satellites, the Sun, the Solar System, the extent of humanities first radio signals, the Milky Way Galaxy, galaxies nearby, distant galaxies, and quasars.  As the distant surface of the microwave background is finally reached, radiation is depicted that was emitted billions of light years away and less than one million years after the Big Bang.  Frequently using the Digital Universe Atlas, every object in the video has been rendered to scale given the best scientific research in 2009, when the video was produced. The film has similarities to the famous Powers of Ten video that has been a favorite of many space enthusiasts for a generation.

Image credit: American Museum of Natural History
Dust and the NGC 7771 Group (2010-01-21)

Galaxies of the NGC 7771 Group are featured in this intriguing skyscape. Some 200 million light-years distant toward the constellation Pegasus, NGC 7771 is the large, edge-on spiral near center, about 75,000 light-years across, with two smaller galaxies just below it. Large spiral NGC 7769 is seen face-on to the right. Galaxies of the NGC 7771 group are interacting, making repeated close passages that will ultimately result in galaxy-galaxy mergers on a cosmic timescale. The interactions can be traced by galaxy distortions and faint streams of stars created by gravitational tides. But a clear view of the galaxy group is difficult to come by, as the deep image also reveals extensive clouds of foreground dust sweeping across the field. The dim, dusty nebulae reflect starlight from our own Milky Way Galaxy and lie only a few hundred light-years above the galactic plane.

Image credit: Ken Crawford
Millennium Annular Solar Eclipse (2010-01-22)

The Moon's shadow raced across planet Earth on January 15. Observers within the central shadow track were able to witness an annular solar eclipse as the Moon's apparent size was too small to completely cover the Sun. A visually dramatic ring of fire, the annular phase lasted up to 11 minutes and 8 seconds depending on location, the longest annular solar eclipse for the next 1,000 years. This picture of the Moon's silhouette just before mid-eclipse was taken within the eclipse path from the city of Kanyakumari at the southern tip of India. The telescopic image was made through a filter that blocks most visible light, but still transmits light from hydrogen atoms. As a result, detailed mottling, or granulation, caused by heat convection in the Sun's atmosphere can be seen around the dark lunar disk.

Image credit: Mikael Svalgaard
Eclipses in the Shade (2010-01-23)

clipses are everywhere in this shady scene. The picture was taken on the Indian Ocean atoll island of Ellaidhoo, Maldives, on January 15, during the longest annular solar eclipse for the next 1,000 years. Tall palm trees provided the shade. Their many crossed leaves created gaps that acted like pinhole cameras, scattering recognizable eclipse images across the white sands of a tropical garden near the beach. From this idyllic location near the centerline of the Moon's shadow track, the ring of fire or annular phase of the eclipse lasted about 10 minutes and 55 seconds.

Image credit: Stephan Heinsius
Watch Jupiter Rotate (2010-01-24)

What would it be like to coast by Jupiter and watch it rotate?  This was just the experience of the New Horizons spacecraft as it approached and flew by Jupiter in 2007.  Clicking on the image will bring up a movie of what the robotic spacecraft saw. Visible above in the extensive atmosphere of the Solar System's largest planet are bands and belts of light and dark clouds, as well as giant rotating storm systems seen as ovals.  Other movies compiled by New Horizons and other passing spacecraft have captured the clouds swirling and moving relative to themselves.  Jupiter has a diameter of about eleven times that of our Earth, and rotates once in about 10 hours. The robotic New Horizons spacecraft, launched four years ago last week, continues to speed toward the outer Solar System and has recently passed the halfway point between Earth and Pluto. New Horizons will reach Pluto in 2015.    Note: Take an Astronomy Class Online for Free
The Magellanic Stream (2010-01-25)

Spanning the sky toward the majestic Clouds of Magellan is an unusual stream of gas: the Magellanic Stream. The origin of this gas remains unknown but likely holds a clue to the origin and fate of our Milky Way's most famous satellite galaxies: the LMC and the SMC. Until recently, two leading genesis hypotheses have been considered: that the stream was created by gas stripped off these galaxies as they passed through the halo of our Milky Way, or that the stream was created by the differential gravitational tug of the Milky Way. Recently, however, wide angle radio images -- including those from the Byrd Green Bank Telescope -- have shown that the Magellanic Stream is longer and older than previously thought, perhaps as old as 2.5 billion years.  These observations bolster a third possible origin for the stream -- that the Large and Small Magellanic Cloud galaxies once passed so close to each other that gravitational tides triggered a burst of star formation that left the stream. Pictured above digitally superposed on a recently-completed all-sky image in visible light, the radio emission of Magellanic stream is shown in false color pink extending across the sky and ending at the two Magellanic galaxies on the lower right.     New Mirror: APOD now available in Hebrew from Israel
Annular Eclipse Over Myanmar (2010-01-26)

A hole crossed the Sun for a few minutes this month, as seen across a thin swath of planet Earth. The event on January 15 was actually an annular solar eclipse, and the hole was really Earth's Moon, an object whose dark half may appear even darker when compared to the tremendously bright Sun. The Moon was too far from Earth to create a total solar eclipse, but instead left well placed observers with a bright surrounding circle called the ring of fire. Pictured above was a complete solar annular eclipse sequence as seen above the Ananda Temple in Bagan, Myanmar.  The image of the ancient temple, built around the year 1100, was taken after sunset on the same day of the eclipse. The next solar eclipse will be a total solar eclipse during 2010 July.

Image credit: Wei Loon Chin
Tethys Behind Titan (2010-01-27)

What's that behind Titan? It's another of Saturn's moons: Tethys.  The robotic Cassini spacecraft orbiting Saturn captured the heavily cratered Tethys slipping behind Saturn's atmosphere-shrouded Titan late last year. The largest crater on Tethys, Odysseus, is easily visible on the distant moon. Titan shows not only its thick and opaque orange lower atmosphere, but also an unusual upper layer of blue-tinted haze.  Tethys, at about 2 million kilometers distant, was twice as far from Cassini as was Titan when the above image was taken. In 2004, Cassini released the Hyugens probe which landed on Titan and provided humanity's first views of the surface of the Solar System's only known lake-bearing moon.
Kemble's Cascade (2010-01-28)

An asterism is just a recognized pattern of stars that is not one the 88 official constellations. For example, one of the most famous (and largest) asterisms is the Big Dipper within the constellation Ursa Major. But this pretty chain of stars, visible with binoculars towards the long-necked constellation of Camelopardalis, is also a recognized asterism. Known as Kemble's Cascade, it contains about 20 stars nearly in a row, stretching over five times the width of a full moon.  Tumbling from the upper right to lower left in the picture, Kemble's Cascade was made popular by astronomy enthusiast Lucian Kemble.  The bright object at the lower left is the relatively compact open cluster of stars, NGC 1502.

Image credit: Noel
Carboni
Mars Opposition 2010 (2010-01-29)

Mars is at opposition tonight, opposite the Sun in planet Earth's sky. Of course, it will be easy to spot because Mars appears close to tonight's Full Moon, also opposite the Sun in Earth's night sky in the constellation Cancer. For this opposition, Mars remains just over 99 million kilometers away, not a particularly close approach for the Red Planet. Still, this sharp view of Mars recorded on January 22nd is an example of the telescopic images possible in the coming days. The planet's whitish north polar cap is at the upper right. Mars' tiny red disk is about 14 arcseconds in angular diameter, less than 1/100th the diameter of the Full Moon.

Image credit: Alan Friedman
Messier 88 (2010-01-30)

Charles Messier described the 88th entry in his 18th century catalog of Nebulae and Star Clusters as a spiral nebula without stars. Of course the gorgeous M88 is now understood to be a galaxy full of stars, gas, and dust, not unlike our own Milky Way. In fact, M88 is one of the brightest galaxies in the Virgo Galaxy Cluster some 50 million light-years away. M88's beautiful spiral arms are easy to trace in this colorful cosmic portait. The arms are lined with young blue star clusters, pink star-forming regions, and obscuring dust lanes extending from a yellowish core dominated by an older population of stars. Spiral galaxy M88 spans over 100,000 light-years.

Image credit: Adam Block
The Mysterious Voynich Manuscript (2010-01-31)

The ancient text has no known title, no known author, and is written in no known language: what does it say and why does it have many astronomy illustrations?  The mysterious book was once bought by an emperor, forgotten on a library shelf, sold for thousands of dollars, and later donated to Yale.  Possibly written in the 15th century, the over 200-page volume is known most recently as the Voynich Manuscript, after its (re-)discoverer in 1912.  Pictured above is an illustration from the book that appears to be somehow related to the Sun. The book labels some patches of the sky with unfamiliar constellations.  The inability of modern historians of astronomy to understand the origins of these constellations is perhaps dwarfed by the inability of modern code-breakers to understand the book's text.  Can the eclectic brain trust of APOD readers make any progress? If you think you can provide any insight, instead of sending us email please participate in a fresh  online discussion. The book itself remains in Yale's rare book collection under catalog number "MS 408."

Image credit: B. E. Schaefer
(LSU)
Shepherd Moon Prometheus from Cassini (2010-02-01)

Another moon of Saturn has been imaged in detail by the Cassini spacecraft. Orbiting Saturn since 2004, the robotic Cassini got its closest look yet at Saturn's small moon Prometheus last week. Visible above in an unprocessed image from 36,000 kilometers away, Prometheus' 100-km long surface was revealed to have an interesting system of bulges, ridges, and craters.  These features, together with the moon's oblong shape and high reflectivity, are now being studied to help better understand the history of Prometheus and Saturn's rings. Prometheus is one of the few shepherd satellites known, as its gravity, along with its companion moon Pandora, confines many smaller ice chucks into Saturn's F Ring.  Cassini's next major targeted flyby is of the moon Rhea on March 2.
Mars and a Colorful Lunar Fog Bow (2010-02-02)

ven from the top of a volcanic crater, this vista was unusual.  For one reason, Mars was dazzlingly bright two weeks ago, when this picture was taken, as it was nearing its brightest time of the entire year. Mars, on the far upper left, is the brightest object in the above picture.  The brightness of the red planet peaked last week near when Mars reached opposition, the time when Earth and Mars are closest together in their orbits. Arching across the lower part of the image is a rare lunar fog bow. Unlike a more commonly seen rainbow, which is created by sunlight reflected prismatically by falling rain, this fog bow was created by moonlight reflected by the small water drops that compose fog. Although most fog bows appear white, all of the colors of the rainbow were somehow visible here.  The above image was taken from high atop Haleakala, a huge volcano in Hawaii, USA.

Image credit: Wally Pacholka
P/2010 A2: Unusual Asteroid Tail Implies Powerful Collision (2010-02-03)

What is this strange object?  First discovered on ground based LINEAR images on January 6, the object appeared unusual enough to investigate further with the Hubble Space Telescope last week. Pictured above, what Hubble saw indicates that P/2010 A2 is unlike any object ever seen before. At first glance, the object appears to have the tail of a comet. Close inspection, however, shows a 140-meter nucleus offset from the tail center, very unusual structure near the nucleus, and no discernable gas in the tail. Knowing that the object orbits in the asteroid belt between Mars and Jupiter, a preliminary hypothesis that appears to explain all of the known clues is that P/2010 A2 is the debris left over from a recent collision between two small asteroids.  If true, the collision likely occurred at over 15,000 kilometers per hour -- five times the speed of a rifle bullet -- and liberated energy in excess of a nuclear bomb. Pressure from sunlight would then spread out the debris into a trailing tail. Future study of P/2010 A2 may better indicate the nature of the progenitor collision and may help humanity better understand the early years of our Solar System, when many similar collisions occurred.
Stardust in Perseus (2010-02-04)

This cosmic expanse of dust, gas, and stars covers close to 3 degrees on the sky in the heroic constellation Perseus. Right of center in the gorgeous skyscape is the dusty blue reflection nebula NGC 1333, about 1,000 light-years away. At that estimated distance, the field of view is about 50 light-years across. Next to NGC 1333 is the reddish glow of shocked hydrogen gas created by energetic jets and winds from stars in the process of formation. Other reflection nebulae are scattered around, along with remarkable dark dust nebulae. Near the edge of a large molecular cloud, they tend to hide the newly formed stars and young stellar objects or protostars from prying optical telescopes. Collapsing due to self-gravity, the protostars form around dense cores embedded in the molecular cloud.

Image credit: Máximo Ruiz
Dust Storm on Mars (2010-02-05)

It's spring for the northern hemisphere of Mars and spring on Mars usually means dust storms. So the dramatic brown swath of dust (top) marking the otherwise white north polar cap in this picture of the Red Planet is not really surprising. Taking advantage of the good views of Mars currently possible near opposition and its closest approach to planet Earth in 2010, this sharp image shows the evolving dust storm extending from the large dark region known as Mare Acidalium below the polar cap. It was recorded on February 2nd with the 1 meter telescope at Pic Du Midi, a mountain top observatory in the French Pyrenees.

Image credit: Jean-Luc Dauvergne
Hong Kong Sky (2010-02-06)

This remarkable scene combines multiple exposures recorded on the evening of January 18th from a waterside perspective in Hong Kong, China. It follows a young crescent Moon, with brilliant planet Jupiter to its left, as they set together in the western sky. Their two luminous trails are faintly paralleled by trails of background stars. But easier to pick out are the short, bright airplane trails converging toward the horizon and the Hong Kong International Airport that seem to offer a frenzied imitation of the celestial tracks. Of course, the reflection of city lights and boat traffic follows the water's surface. Streaking car lights define the span of the cable-stayed Ting Kau bridge.

Image credit: Peter Lau
The Einstein Cross Gravitational Lens (2010-02-07)

Most galaxies have a single nucleus -- does this galaxy have four?  The strange answer leads astronomers to conclude that the nucleus of the surrounding galaxy is not even visible in this image.  The central cloverleaf is rather light emitted from a background  quasar.  The gravitational field of the visible foreground galaxy breaks light from this distant quasar into four distinct images.  The quasar must be properly aligned behind the center of a massive galaxy for a mirage like this to be evident.  The general effect is known as gravitational lensing, and this specific case is known as the Einstein Cross.  Stranger still, the images of the Einstein Cross vary in relative brightness, enhanced occasionally by the additional gravitational microlensing effect of specific stars in the foreground galaxy.

Image credit: J. Rhoads
A Sun Halo Over Cambodia (2010-02-08)

Have you ever seen a halo around the Sun?  This fairly common sight occurs when high thin clouds containing millions of tiny ice crystals cover much of the sky.  Each ice crystal acts like a miniature lens.  Because most of the crystals have a similar elongated hexagonal shape, light entering one crystal face and exiting through the opposing face refracts 22 degrees, which corresponds to the radius of the Sun halo.  A similar Moon halo may be visible during the night.  Pictured above, a nearly complete sun halo was photographed high above the ancient Bayon temple in Angkor, Cambodia. Exactly how ice-crystals form in clouds remains under investigation.

Image credit: Nagy Attila
Night Launch of the Space Shuttle Endeavour (2010-02-09)

Sometimes, the space shuttle launches at night.  Pictured above, the space shuttle Endeavour lifted off in yesterday's early morning hours from Launch Pad 39A in Kennedy Space Center, Florida, USA, bound for the International Space Station (ISS). A night launch, useful for reaching the space station easily during some times of the year, frequently creates vivid launch imagery. The shuttle, as pictured above, is framed by an enormous but typical exhaust plume ejected as the shuttle's powerful rockets began lifting the two million kilogram space bus into Earth orbit. Endeavour's mission, labeled STS-130, includes the delivery of the Tranquility module to the space station.  Tranquility will provide extra room for space station astronauts and includes a large circular set of windows designed to bestow vastly improved views of the Earth, the night sky, and the space station itself.
Sakurajima Volcano with Lightning (2010-02-10)

Why does a volcanic eruption sometimes create lightning? Pictured above, the Sakurajima volcano in southern Japan was caught erupting early last month. Magma bubbles so hot they glow shoot away as liquid rock bursts through the Earth's surface from below.  The above image is particularly notable, however, for the lightning bolts caught near the volcano's summit.  Why lightning occurs even in common thunderstorms remains a topic of research, and the cause of volcanic lightning is even less clear. Surely, lightning bolts help quench areas of opposite but separated electric charges. One hypothesis holds that catapulting magma bubbles or volcanic ash are themselves electrically charged, and by their motion create these separated areas. Other volcanic lightning episodes may be facilitated by charge-inducing collisions in volcanic dust. Lightning is usually occurring somewhere on Earth, typically over 40 times each second.
Star Cluster M34 (2010-02-11)

This pretty, open cluster of stars, M34, is about the size of the Full Moon on the sky. Easy to appreciate in small telescopes, it lies some 1,800 light-years away in the constellation Perseus. At that distance, M34 physically spans about 15 light-years. Formed at the same time from the same cloud of dust and gas, all the stars of M34 are about 200 million years young. But like any open star cluster orbiting in the plane of our galaxy, M34 will eventually disperse as it experiences gravitational tides and encounters with the Milky Way's interstellar clouds and other stars. Over four billion years ago, our own Sun was likely formed in a similar open star cluster.

Image credit: Bob Franke
Teide Sky Trails (2010-02-12)

The snow capped Teide volcano is reflected in a pool of water in this nearly symmetric night sky view from the Canary Island Tenerife. Bright north star Polaris stands above the peak in an exposure that also captures the brilliant trail of a polar orbiting Iridium satellite. Of course, with the camera fixed to a tripod, the stars themselves produce concentric trails in long exposures, a reflection of the Earth's rotation around its axis. In fact, you can add about 4.5 hours of exposure time to this image by just sliding your cursor over the picture. Large astronomical observatories also take advantage of the calm Canary Island sky.

Image credit: Daniel López
Waterway to Orbit (2010-02-13)

The 32nd shuttle mission to the International Space Station, STS-130, left planet Earth on February 8. Its early morning launch to orbit from Kennedy Space Center's pad 39A followed the long, graceful, eastward arc seen in this 2 minute time exposure. Well composed, the dramatic picture also shows the arc's watery reflection from the Intracoastal Waterway Bridge, in Ponte Vedra, Florida, about 115 miles north of the launch site. In the celestial background a waning crescent Moon and stars left their own short trails against the still dark sky. The brightest star trail near the moon was made by red supergiant Antares, alpha star of the constellation Scorpius.

Image credit: James Vernacotola