juliensimon/nasa-apod huggingface dataset:
Eclipsed Moon in Infrared (2005-04-23)

In September of 1996, the Midcourse Space Experiment (MSX) satellite had a spectacular view of a total lunar eclipse from Earth orbit. SPIRIT III, an on board infrared telescope, was used to repeatedly image the moon during the eclipse. Above is one of the images taken during the 70 minute totality, the Moon completely immersed in the Earth's shadow. Infrared light has wavelengths longer than visible light - humans can not see it but feel it as heat. So, the bright spots correspond to the warm areas on the lunar surface, and dark areas are cooler. The brightest spot below and left of center is the crater Tycho, while the dark region at the upper right is the Mare Crisium. Of course, this Sunday's lunar eclipse will not be a total, or even a partial one. Instead, the Moon will glide through the subtle outer portion of the Earth's shadow in a penumbral eclipse of the Moon.
M16: Stars from Eagle's EGGs (2005-04-24)

Newborn stars are forming in the Eagle Nebula.  This image, taken with the Hubble Space Telescope in 1995, shows evaporating gaseous globules (EGGs) emerging from pillars of molecular hydrogen gas and dust.  The giant pillars are light years in length and are so dense that interior gas contracts gravitationally to form stars.  At each pillars' end, the intense radiation of bright young stars causes low density material to boil away, leaving stellar nurseries of dense EGGs exposed.  The Eagle Nebula, associated with the open star cluster M16, lies about 7000 light years away.
The Fairy of Eagle Nebula (2005-04-25)

The dust sculptures of the Eagle Nebula are evaporating.  As powerful starlight whittles away these cool cosmic mountains, the statuesque pillars that remain might be imagined as mythical beasts.  Pictured above is one of several striking dust pillars of the Eagle Nebula that might be described as a gigantic alien fairy.   This fairy, however, is ten light years tall and spews radiation much hotter than common fire.  The greater Eagle Nebula, M16, is actually a giant evaporating shell of gas and dust inside of which is a growing cavity filled with a spectacular stellar nursery currently forming an open cluster of stars.  The above image in scientifically re-assigned colors was released as part of the fifteenth anniversary celebration of the launch of the Hubble Space Telescope.
A Martian Dust Devil Passes (2005-04-26)

What goes there across the plains of Mars?  A dust devil.  For the first time, definitive movies of the famous spinning dust towers have been created from ground level.  The robot rover Spirit has now imaged several dust devils from its hillside perch just within the past two months.  Each image in the above sequence was taken about 20 seconds apart.  Inspection of the digitally resized images show the passing dust devil raising Martian dust so thick that it casts a shadow.  The new dust devil movies have been made possible by a new hybrid interaction system where the robot Spirit on Mars takes many images and humans on Earth inspect thumbnails and decide which full resolution images to send back.
The Hercules Cluster of Galaxies (2005-04-27)

These are galaxies of the Hercules Cluster, an archipelago of "island universes" a mere 650 million light-years distant. This cluster is loaded with gas and dust rich, star forming, spiral galaxies but has relatively few elliptical galaxies, which lack gas and dust and the associated newborn stars. Colors in the composite image show the star forming galaxies with a blue tint and ellipticals with a slightly yellowish cast. In this cosmic vista many galaxies seem to be colliding or merging while others seem distorted - clear evidence that cluster galaxies commonly interact. Over time, the galaxy interactions are likely to affect the the content of the cluster itself. Researchers believe that the Hercules Cluster is significantly similar to young galaxy clusters in the distant, early Universe and that exploring galaxy types and their interactions in nearby Hercules will help unravel the threads of galaxy andcluster evolution.

Image credit: Jim Misti 
(Misti Mountain Observatory)
M51: Cosmic Whirlpool (2005-04-28)

Follow the handle of the Big Dipper away from the dipper's bowl, until you get to the handle's last bright star. Then, just slide your telescope a little south and west and you might find this stunning pair of interacting galaxies, the 51st entry in Charles Messier's famous catalog. Perhaps the original spiral nebula, the large galaxy with well defined spiral structure is also cataloged as NGC 5194. Its spiral arms and dust lanes clearly sweep in front of its companion galaxy (right), NGC 5195. The pair are about 31 million light-years distant and officially lie within the boundaries of the small constellation Canes Venatici. Though M51 looks faint and fuzzy in small, earthbound telescopes, this sharpest ever picture of M51 was made in January 2005 with the Advanced Camera for Surveys on board the Hubble Space Telescope.
Small Moon Epimetheus (2005-04-29)

Small saturnian moon Epimetheus (ep-ee-MEE-thee-us) is at most 116 kilometers across. Its cratered surface and irregular shape are highlighted by dramatic shadows in this composite close-up image from the Cassini spacecraft. However, orbiting 91,000 kilometers above Saturn's cloud tops, Epimetheus is not alone. Similar in size, saturnian moon Janus occupies an orbit separated from Epimetheus' by only about 50 kilometers. The two actually approach each other once every four years, but instead of colliding, the moons deftly exchange orbits and move apart again! In fact, co-orbiting Epimetheus and Janus both consist mostly of porous water ice and could have formed from the breakup of a single parent body. The small moons are also believed to play a role in maintaining the outer edge of Saturn's A ring.
The Moons of Earth (2005-04-30)

While orbiting the planet during their June 1998 mission, the crew of the Space Shuttle Discovery photographed this view of two moons of Earth. Thick storm clouds are visible in the lovely blue planet's nurturing atmosphere and, what was then Earth's largest artificial moon, the spindly Russian Mir Space Station can be seen above the planet's limb. The bright spot to the right of Mir is Earth's very large natural satellite, The Moon. The Mir orbited planet Earth once every 90 minutes about 200 miles above the planet's surface or about 4,000 miles from Earth's center. The Moon orbits once every 28 days at a distance of about 250,000 miles from the center of the Earth.
Planetary Nebula Mz3: The Ant Nebula (2005-05-01)

Why isn't this ant a big sphere?  Planetary nebula Mz3 is being cast off by a star similar to our Sun that is, surely, round.  Why then would the gas that is streaming away create an ant-shaped nebula that is distinctly not round?  Clues might include the high 1000-kilometer per second speed of the expelled gas, the light-year long length of the structure, and the magnetism of the star  visible above at the nebula's center.  One possible answer is that Mz3 is hiding a second, dimmer star that orbits close in to the bright star.  A competing hypothesis holds that the central star's own spin and magnetic field are channeling the gas.  Since the central star appears to be so similar to our own Sun, astronomers hope that increased understanding of the history of this giant space ant can provide useful insight into the likely future of our own Sun and Earth.
Methusaleh Outcrop on Mars (2005-05-02)

What is the history of the outcropping of rock called Methuselah?  The unusual rock group is visible on the left of the above image taken by the robot Spirit rover current exploring Mars.  Methuselah was discovered while maneuvering over hilly terrain and shows unusual multiple layering that caught the attention of the rover science team.  Since the above representative color image was taken about three weeks ago, Spirit has moved in to get a closer look.  Also visible in the above image are another rock outcrop dubbed Larry's Lookout on the upper right and a larger Clark Hill in the left background.  On the far right is a more distant peak of the Columbia Hills.
Solar System Rising Over Fire Island (2005-05-03)

If you wait long enough, the entire Solar System will rise before you.  To see such a sight, however, you will need to look in the direction of the ecliptic.  All of the planets and their moons orbit the Sun in nearly the same plane, the ecliptic plane.   From the Earth, this means that each day they will all rise in nearly the same direction - and later set in the opposite direction. Ten years ago, a series of time exposures caught, left to right, the Sun, Venus, the Moon, and Jupiter, all rising in the ecliptic plane behind Fire Island, New York, USA.  Exposures were taken every six minutes and digitally superposed on an image taken from the same location at sunrise.  Smaller members of our Solar System, including most comets and many asteroids, do not always move along the ecliptic plane.  The picturesque Fire Island Lighthouse, visible in the foreground, was built in 1826 and is still in use today.

Image credit: Larry Landolfi (Landolfi Photography)
Cassini Spacecraft Crosses Saturn's Ring Plane (2005-05-04)

If this is Saturn, where are the rings?  When Saturn's "appendages" disappeared in 1612, Galileo did not understand why.   Later that century, it became understood that Saturn's unusual protrusions were rings and that when the Earth crosses the ring plane, the edge-on rings will appear to disappear.  This is because Saturn's rings are confined to a plane many times thinner, in proportion, than a razor blade.  In modern times, the robot Cassini spacecraft orbiting Saturn now also crosses Saturn's ring plane.  A series of plane crossing images from late February was dug out of the vast online Cassini raw image archive by interested Spanish amateur Fernando Garcia Navarro.  Pictured above, digitally cropped and set in representative colors, is the striking result.  Saturn's thin ring plane appears in blue, bands and clouds in Saturn's upper atmosphere appear in gold, and dark shadows of the rings curve across the top of the gas giant planet.  Moons appear as bumps in the rings.
Mira: The Wonderful Star (2005-05-05)

To seventeenth century astronomers, Omicron Ceti or Mira was known as a wonderful star - a star whose brightness could change dramatically in the course of about 11 months. Modern astronomers now recognize an entire class of long period Mira-type variables as cool, pulsating, red giant stars, 700 or so times the diameter of the Sun. Only 420 light-years away, red giant Mira (Mira A, right) itself co-orbits with a companion star, a small white dwarf (Mira B). Mira B is surrounded by a disk of material drawn from the pulsating giant and in such a double star system, the white dwarf star's hot accretion disk is expected to produce some x-rays. But this sharp, false-color image from the Chandra Observatory also captures the cool giant star strongly flaring at x-ray energies, clearly separated from the x-ray emission of its companion's accretion disk. Placing your cursor over the Chandra x-ray image of Mira will reveal an artist's vision of this still wonderful interacting binary star system.
Hybrid Solar Eclipse (2005-05-06)

April's spectacular geocentric celestial event was a rare hybrid eclipse of the Sun - a total or an annular eclipse could be seen depending on the observer's location. For Fred Espenak, aboard a gently swaying ship within the middle of the Moon's shadow track about 2,200 kilometers west of the Galapagos, the eclipse was total, the lunar silhouette exactly covering the bright solar disk for a few brief moments. His camera captured a picture of totality revealing the extensive solar corona and prominences rising above the Sun's edge. But for Stephan Heinsius, near the end of the shadow track at Penonome Airfield, Panama, the Moon's apparent size had shrunk enough to create an annular eclipse, showing a complete annulus of the Sun's bright disk as a dramatic ring of fire.  Pictures from the two locations are compared above. How rare is such a hybrid eclipse? Calculations show that during the 21st century just 3.1% (7 out of 224) of solar eclipses are hybrid while hybrids comprise about 5% of all solar eclipses over the period 2000 BC to AD 4000.

Image credit: Left:
Fred Espenak -
Right:
Stephan Heinsius
NGC 3314: When Galaxies Overlap (2005-05-07)

NGC 3314 consists of two large spiral galaxies which just happen to almost exactly line-up. The foreground spiral is viewed nearly face-on, its pinwheel shape defined by young bright star clusters. But against the glow of the background galaxy, dark swirling lanes of interstellar dust are also seen to echo the face-on spiral's structure. The dust lanes are surprisingly pervasive, and this remarkable pair of overlapping galaxies is one of a small number of systems in which absorption of visible light can be used to directly explore the distribution of dust in distant spirals. NGC 3314 is about 140 million light-years away in the multi-headed constellation Hydra. This color composite was constructed from Hubble Space Telescope images made in 1999 and 2000.
CMBR Dipole: Speeding Through the Universe (2005-05-08)

Our Earth is not at rest.  The Earth moves around the Sun.  The Sun orbits the center of the Milky Way Galaxy.  The Milky Way Galaxy orbits in the Local Group of Galaxies.  The Local Group falls toward the Virgo Cluster of Galaxies.  But these speeds are less than the speed that all of these objects together move relative to the cosmic microwave background radiation (CMBR).  In the above all-sky map, radiation in the Earth's direction of motion appears blueshifted and hence hotter, while radiation on the opposite side of the sky is redshifted and colder.  The map indicates that the Local Group moves at about 600 kilometers per second relative to this primordial radiation.  This high speed was initially unexpected and its magnitude is still unexplained.  Why are we moving so fast?  What is out there?
Stars, Dust and Nebula in NGC 6559 (2005-05-09)

When stars form, pandemonium reigns.  A textbook case is the star forming region NGC 6559.  Visible above are red glowing emission nebulas of hydrogen, blue reflection nebulas of dust, dark absorption nebulas of dust, and the stars that formed from them.  The first massive stars formed from the dense gas will emit energetic light and winds that erode, fragment, and sculpt their birthplace.  And then they explode.  The resulting morass can be as beautiful as it is complex.  After tens of millions of years, the dust boils away, the gas gets swept away, and all that is left is a naked open cluster of stars.

Image credit: Jean-Charles Cuillandre
The First Image of an Extra Solar Planet (2005-05-10)

It's the faint red object, not the bright white one that might be a historic find.  The white object is surely a brown dwarf star.  Quite possibly, however, the red object is the first direct image of a planet beyond our Solar System.  The intriguing possibility was first reported last year, but many astronomers weren't then convinced that the "planet" was not just a background star.   Earlier this year, the 2M1207 star system was imaged twice more in an effort to resolve the issue.  To the delight of the scientific team, the objects kept the same separation, indicating that they are gravitationally bound.  The faint red object 2M1207b is therefore 100 times fainter, intrinsically, than the bright white brown dwarf 2M1207a -- a characteristic well explained by a planet roughly five times the mass of Jupiter.  The discovery - still subject to further confirmation - is considered a step toward the more ambitious goal of imaging Earth-like planets orbiting distant stars.  The above image was taken with the high-resolution adaptive-optic NaCo camera attached to the 8-meter Very Large Telescope Yepun in Chile.
The Sombrero Galaxy in Infrared (2005-05-11)

This floating ring is the size of a galaxy.  In fact, it is part of the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies.  The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light.  The above image shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in optical light.  The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away.  M104 can be seen with a small telescope in the direction of the constellation of Virgo.
Stars, Galaxies, and Comet Tempel 1 (2005-05-12)

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.

Image credit: Johannes Schedler
(Panther Observatory)
When the Moon Was Young (2005-05-13)

Remember when the Moon was young? It was just last Monday. On May 9th, this slender crescent Moon was recorded at a tender age of 34 hours and 18 minutes. Well, OK ... when calculating the lunar age during a lunation or complete cycle of phases - from New Moon to Full Moon and back to New Moon again - the Moon never gets more than around 29.5 days old. Still, a young Moon can be a rewarding sight, even for casual skygazers, though the slim crescent is relatively faint and only easy to see low in the west as the sky grows dark after sunset. Sighting this young Moon last Monday, lucky astronomer Stefan Seip was also treated to a very dramatic telescopic view of an airliner flying in front of the distant sunlit crescent. At a high altitude, the jet's stunning contrails reflect the strongly reddened light of the Sun setting below the western horizon.

Image credit: Stefan Seip
NGC 3370: A Sharper View (2005-05-14)

Similar in size and grand design to our own Milky Way, spiral galaxy NGC 3370 lies about 100 million light-years away toward the constellation Leo. Recorded here in exquisite detail by the Hubble Space Telescope's Advanced Camera for Surveys, the big, beautiful face-on spiral does steal the show, but the sharp image also reveals an impressive array of background galaxies in the field, strewn across the more distant Universe. Looking within NGC 3370, the image data has proved sharp enough to study individual pulsating stars known as Cepheids which can be used to accurately determine this galaxy's distance. NGC 3370 was chosen for this study because in 1994 the spiral galaxy was also home to a well studied stellar explosion -- a type Ia supernova. Combining the known distance to this standard candle supernova, based on the Cepheid measurements, with observations of supernovae at even greater distances, can reveal the size and expansion rate of the Universe itself.
On the Origin of Gold (2005-05-15)

Where did the gold in your jewelry originate?  No one is completely sure.  The relative average abundance in our Solar System appears higher than can be made in the early universe, in stars, and even in typical supernova explosions.  Some astronomers now suggest that neutron-rich heavy elements such as gold might be most easily made in rare  neutron-rich explosions such as the collision of neutron stars.  Pictured above is a computer-animated frame depicting two neutron stars spiraling in toward each other, just before they collide.  Since neutron star collisions are also suggested as the origin of short duration gamma-ray bursts, it is possible that you already own a souvenir from one of the most powerful explosions in the universe.
Deep Impact Spacecraft Hurtles Toward Comet (2005-05-16)

What happens when you crash into a comet? That was a question considered by astronomers when they designed the Deep Impact mission, launched in January.  This coming July 4, the Deep Impact spaceship will reach its target - Comet Tempel 1 -- and release an impactor over five times the mass of a person toward its surface.  The mothership will photograph the result.  The remaining crater may tell how Tempel 1 is constructed.  If, for example, Comet Tempel 1 is an extremely loose pile of debris, the impactor may leave little or no discernable crater.  On the other hand, if the comet's surface is relatively firm, the impactor's ripple may leave quite a large crater.  A contest is even being held to predict the size of the resulting crater.  Pictured above is an artist's impression of the initial encounter between the spacecraft and the comet.
A Panorama of Mars from Larry's Lookout (2005-05-17)

Scroll right to see a breathtaking panorama of Mars from Larry's Lookout.  The lookout occurs near the peak of Husband Hill in the Columbia Hills.  The summit of Husband Hill is visible 200 meters in the distance toward the center of the 360-degree near-true-color picture.  The robot rover Spirit took images that compose the above mosaic over four Martian days.  After taking the image sequence, Spirit carefully picked its way to toward Husband Hill's summit.  On the far right, near distant rover tracks, is a recently investigated area dubbed Paso Robles that was found to contain high amounts of sulfur.
Three Kilometers Above Titan (2005-05-18)

What did the Huygens probe see as it descended toward Saturn's Moon Titan? In January the robot Cassini spacecraft now orbiting Saturn released a probe through the dense cloud decks of one of the Solar System's most mysterious moons.  Below the clouds, as it descended, the probe took images of the approaching surface as well as several images from the surface itself.  Many of the images have now been digitally merged and scaled into the above perspective from 3,000 meters high.  The above stereographic projection shows a 360-degree wide-angle view of the surface of Titan.  The bright areas toward the top and left of the image are thought to be relatively high ground laced with drainage channels cut by rivers of methane.  The bright shapes on the right are now hypothesized to be ridges of ice gravel.  Huygen's landing site, labeled, appears to be on a type of dark dry lakebed, once fed by a large dark flow channel on the left.  The Huygen's probe lasted an unexpectedly long three hours on Titan's harsh surface.
X-Ray Stars in the Orion Nebula (2005-05-19)

When our middle-aged Sun was just a few million years old it was thousands of times brighter in x-rays. In fact, it was likely similar to some of the stars found in this false-color x-ray composite of the Orion Nebula region from the Chandra Observatory. The image is centered on bright stars of the nebula's Trapezium star cluster, and while analyzing the Chandra data astronomers have now found examples of young, sun-like stars producing intense x-ray flares. It sounds dangerous, but the situation may actually favor the formation of hospitable planetary systems like our own. Energetic flares can produce turbulence in the planet-forming disks surrounding the stars - preventing rocky earth-like planets from spiraling uncomfortably close to and even falling into their active, young parent stars. About 1,500 light-years away, the Orion Nebula is the closest large stellar nursery. At that distance, this Chandra image spans about 10 light-years.