juliensimon/nasa-apod huggingface dataset:
A Distant Destiny (1998-01-14)

Watching galaxies recede, observational astronomers of the 20th century discovered an astounding fact - the Universe is expanding. Will it continue to expand forever? The speed of light is finite so looking into the distant Universe is equivalent to looking at the distant past. These three Hubble Space Telescope images show some of the most distant detectable supernovae - stellar explosions, five to seven billion light-years away, which occurred before the Sun was formed. As recently reported, the apparent brightness and expansion velocities associated with these and other distant supernovae are beginning to suggest that the expansion rate of the Universe has not slowed but increased over time and that the expansion of the Universe is destined to continue.
Eugene Shoemaker: 1928-1997 (1998-01-15)

ugene Shoemaker's passion was Astrogeology. He dreamed of going to the Moon. Credited with inventing the branch of Astrogeology within the U.S. Geological Survey, his contributions to the field and the study of impact craters, lunar science, asteroids, and comets are legendary. Though his own career as an astronaut/geologist was sidelined by a health problem, he helped train the Apollo astronauts in geology and the investigation of the lunar surface. Seen here at Meteor Crater, Arizona in the mid 1960s, Shoemaker was killed in a tragic car accident in July 1997. He is survived by his wife and professional colleague, Carolyn, and children. In a fitting tribute conceived by a former student, Eugene Shoemaker's ashes were placed on-board the Lunar Prospector spacecraft which has now successfully reached a polar mapping orbit around the Moon. After completing its scientific mission, the spacecraft will ultimately impact the lunar surface.
Dusting Spiral Galaxies (1998-01-16)

How much dust is in spiral galaxies? Does it block out much of the starlight? Because astronomers rely on an accurate knowledge of galaxy properties to investigate a wide range of problems, like galaxy and quasar evolution and the nature of dark matter, answers to simple questions like this are key. This striking, detailed Hubble Space Telescope image of dust in the outer reaches of a foreground spiral galaxy (left) back lit by an elliptical galaxy offers an elegant approach to providing the answers. As expected, dust lanes in the foreground galaxy seem to be associated with spiral arms. But surprisingly, many dust regions are not completely opaque and the dust is more smoothly distributed than anticipated. This "overlapping" pair of galaxies is cataloged as AM1316-241 and is about 400 million light-years away in the constellation Hydra.
At The Core Of M15 (1998-01-17)

Densely packed stars in the core of the globular cluster M15 are shown in this Hubble Space Telescope (HST) image. The star colors roughly indicate their temperatures - hot stars appear blue, cooler stars look reddish-orange. The region visible here is only about 1.6 light-years across, compared to the 4.3 light-year distance to our own Sun's nearest neighbor. Imagine the night sky viewed from a planet orbiting a star near this cluster's center! M15 has long been recognized as one of the densest clusters of stars in our galaxy outside of the galactic center itself. Even the unprecedented resolving power of the HST cameras could not separate the individual stars in its innermost regions. However, this HST image reveals that the density of stars continues to rise toward the cluster's core, suggesting that a sudden, runaway collapse due to the gravitational attraction of many closely packed stars or a single central massive object, perhaps a black hole, could account for the core's extreme density.
Saturn, Rings, and Two Moons (1998-01-18)

NASA's robot spacecraft Voyager 2 made this image of Saturn as it began to explore the Saturn system in 1981. Saturn's famous rings are visible along with two of its moons, Rhea and Dione which appear as faint dots on the right and lower right part of the picture.  Astronomers believe that Saturn's moons play a fundamental role in sculpting its elaborate ring system. A robot spacecraft named Cassini was launched last October and is expected to rendezvous with the giant gas planet in 2004.
The Hubble 5 Planetary Nebula (1998-01-19)

The Hubble Double Bubble Planetary Nebula is bubbling over with excitement. More mundanely known as Hubble 5, this bipolar planetary nebula is being created by a hot wind of particles streaming away from the central star system.  The hot gas expands into the surrounding interstellar medium in a fashion similar to the inflation of hot air balloons. A supersonic shock-wave can form at the boundary, causing newly excited gas there to shine as electrons recombine with resident elements.  In the above picture, colors are assigned according to the energy of the recombinant radiation.  This star system lies about 2200 light-years from Earth, and likely includes a Sun-like star slowly transforming itself into a white dwarf.
Arachnoids on Venus (1998-01-20)

Arachnoids are large structures of unknown origin that have been found only on the surface of Venus. Arachnoids get their name from their resemblance to spider-webs.  They appear as concentric ovals surrounded by a complex network of fractures, and can span 200 kilometers.  Radar echoes from the Magellan spacecraft that orbited Venus from 1990 to 1994 built up this image.  Over 30 arachnoids have been identified on Venus, so far.  The Arachnoid might be a strange relative to the volcano, but possibly different arachnoids are formed by different processes.
Our Dusty Universe (1998-01-21)

What's black & white and red all over?  Add our universe to this list.  Adrift in a vast sea of darkness are not only familiar bright stars but dust that glows predominantly in far-infrared light.  This cosmological dust was recently discovered in data taken previously by the COBE satellite, and visible as a diffuse glow visible in the above image.  The amount of dust in the universe is important because it is a measure of the number of stars that created it, of the number of stars that are cloaked by it, and of the amount of distortion created in measurements of the distant universe.
Closer To Beta Pic (1998-01-22)

What did our Solar System look like as the planets were forming? Since the 1980s, astronomers have been pointing toward Beta Pictoris, a young, sun-like star a mere 50 light-years distant, as a likely example. Beta Pic is surrounded by a disk of dust which we view nearly edge-on. The dust disk shines by reflected starlight and has been examined with ever increasing detail to search for signs of planetary formation. The trick is to follow the disk as close in to the star as possible, without being overwhelmed by the direct starlight. To make this Hubble Space Telescope image, a coronagraph was used to block the direct starlight and achieve the closest view yet. The false color picture shows the inner section of the dusty disk to within nearly 1.5 billion miles of the star itself, about the scale of the orbit of Uranus. The obvious warp is indirect evidence that a planet now orbits this young sun, slightly inclined to the disk. The planet's gravitational pull would produce the visible distortion.
Jovian Aurora (1998-01-23)

These two recently released Hubble Space Telescope close-ups show the Northern and Southern lights ... on Jupiter. Like aurora on Earth, these Jovian aurora are caused by charged particles funneled into the atmosphere above the planet's North (right) and South poles by magnetic fields. But Jupiter's magnetic field is extremely large and ionized material expelled from the volcanic moon Io is trapped in it creating light shows 1,000 times more intense than Earth's auroral storms. Charged particles released by Io are also funneled along magnetic flux tubes which form a direct "bridge" to the Jovian atmosphere. The result is auroral hot spots - magnetic footprints 600 or more miles across which race over Jupiter's cloud tops. A hot spot is visible in both images as a comet-like feature just outside the polar auroral rings. In these false color ultraviolet images, Jupiter's limb (edge) appears dull brown while the auroral displays are shades of white and blue.
The Large Cloud Of Magellan (LMC) (1998-01-24)

Ferdinand Magellan and his crew had plenty of time to study the southern sky during their famous voyage around the world. As a result, two fuzzy cloud-like objects, not visible to northern hemisphere dwellers, are now known as the Clouds of Magellan. These star clouds are small irregular galaxies, satellites of our larger Milky Way spiral galaxy. The Large Magellanic Cloud (LMC) pictured above is only about 180,000 light-years distant - the only known galaxy closer is the Sagittarius Dwarf. Both the LMC and the Small Magellanic Cloud (SMC) are joined to the Milky Way by a stream of cold hydrogen gas. An unusual effect called gravitational lensing has recently been detected in a few LMC stars, and there is hope this could tell us important information about the true composition of our universe.

Image credit: D. Malin (AAO),
AATB, 
ROE,
UKS Telescope
The Small Cloud of Magellan (SMC) (1998-01-25)

Almost unknown to casual observers in the northern hemisphere, the southern sky contains two diffuse wonders known as the Magellanic Clouds. The Magellanic Clouds are small irregular galaxies orbiting our own larger Milky Way spiral galaxy.  The Small Magellanic Cloud (SMC), pictured here, is about 250,000 light years away and contains a preponderance of young, hot, blue stars indicating it has undergone a recent period of star formation.  There is evidence that the SMC is not gravitationally bound to the LMC.

Image credit: D. Malin 
(AAO),
AATB, 
ROE,
UKS Telescope
Interplanetary Spacecraft Passes Earth (1998-01-26)

Last Thursday an interplanetary spacecraft flew right past the Earth.  The above images show sunlight momentarily reflected from this spacecraft's solar panels.  No aliens were involved - the Near Earth Asteroid Rendezvous (NEAR) mission actually originated from Earth. Launched in 1996, NEAR zipped past the asteroid 253 Mathilde last June. This Earth flyby gravitationally deflects NEAR onto a trajectory passing the asteroid 433 Eros next year.  Above, NEAR appears to move through the constellation of Perseus, as  clouds created a changing diffuse white glow.  NEAR was only visible for about 2 minutes from San Jose, California, where these image-intensified video camera observations were taken.

Image credit: P. Jenniskens 
(NASA
/ARC/
Leonid98)
The Great Nebula in Orion (1998-01-27)

The Great Nebula in Orion can be found just below and to the left of the easily identifiable belt of three stars in the popular constellation Orion. This fuzzy patch contains one of the closest stellar nurseries, lying at a distance of about 1500 light years. In the above picture, the red region on the left consists of nebulae designated  M42 and M43 and contains the bright Trapezium open cluster.  The blue region on the right is a nebula primarily reflecting the light from internal bright stars.  Recent observations of the Orion Nebula by the Hubble Space Telescope have located solar-system sized star-forming regions.

Image credit: J. Ware
The Infrared Sky (1998-01-28)

Three major sources contribute to the far-infrared sky: our Solar System, our Galaxy, and our Universe. The above image, in representative colors, is a projection of the entire infrared sky created from years of observations by the robot spacecraft COBE. Our Solar System is evidenced most prominently by the S-shaped blue sash called zodiacal light, created by small pieces of rock and dust orbiting between the Sun and Jupiter.  Our Galaxy is evidenced by the bright band of light that crossed the middle of the image, created mostly by dust that laces the disk of our Milky Way. Close inspection of the image reveals that the background is not completely dark, indicating that our Universe itself provides a diffuse glow, created by the dust left over from the star formation throughout the Universe.
The Earth-Moon System (1998-01-29)

This evocative mosaic image of the Earth-Moon system was recorded by NASA's Near Earth Asteroid Rendezvous (NEAR) spacecraft earlier this month. The relative sizes shown are appropriate for viewing both the Earth and Moon from a distance of about 250,000 miles, although the apparent brightness of the Moon has been increased by about a factor of five for the sake of appearances. This space-based perspective is a unique one, the bland and somber Lunar Southern Hemisphere contrasting strongly with blue oceans, swirling clouds, and the bright icy white continent of Antarctica on planet Earth. Though its lack of atmosphere and oceans make it relatively dull looking, the Earth's moon is one of the largest moons in the solar system - even larger than the planet Pluto. During this recent flyby of the Earth-Moon system, the NEAR spacecraft used Earth's gravity to deflect it towards its ultimate destination, the Asteroid 433 Eros. It is scheduled to arrive at Eros in January 1999.
Tempel-Tuttle: The Leonid Comet (1998-01-30)

Star trails streak this composite time exposure of Comet Tempel-Tuttle recorded by T. Puckett on January 26. Presently passing through the inner solar system on its 33 year orbit around the Sun, Tempel-Tuttle has brightened unexpectedly, but binoculars or small telescopes are still required to visually observe it. Tempel-Tuttle is also called "the Leonid Comet" as the yearly Leonid meteor shower results when the Earth crosses this comet's orbital plane and encounters cometary dust. So, while not currently rivaling the spectacle of a Hyakutake or Hale-Bopp, Tempel-Tuttle may still put on a show. When the Earth plunges through Tempel-Tuttle's debris tail in November of this year, many sky-watchers are anticipating an extremely active meteor shower to result, perhaps even a meteor storm!

Image credit: T. Puckett
(Puckett Observatory)
Hamlet of Oberon (1998-01-31)

What's in a name? Since 1919, the International Astronomical Union has been charged with the task of establishing "conventional" nomenclature for planets, satellites, and surface features. For the remote Uranian system of moons, namesakes from Shakespearean works have been chosen. Thus Oberon, king of the mid-summer night fairies, is also Uranus' most distant and second largest moon. Hamlet is the tragically dark, large and princely crater on its surface (right of center). The above image represents known surface features of Oberon and was constructed by the U.S. Geological Survey (USGS) based on data from NASA's robot explorer Voyager 2. In 1986, Voyager 2 flew through the Uranian system - so far it has been the only spacecraft to do so.
NGC 1977: Blue Reflection Nebula in Orion (1998-02-01)

The Orion Nebula is visible to the unaided eye as a fuzzy patch near the famous belt of three stars in the constellation Orion. The above picture captures a part of the Orion Nebula that primarily reflects light from bright Orion stars. This reflection nebula appears blue because the blue light from the neighboring stars scatters more efficiently from nebula gas than does red light. The dark lanes are composed of mostly interstellar dust - fine needle-shaped carbon grains.

Image credit: Anglo-Australian Telescope
Board
A Triple Eclipse on Jupiter (1998-02-02)

Part of Jupiter is missing.  Actually, three parts appear to be missing.  In reality though, the three dark spots seen in the above photograph are only shadows. The unusual alignment of three of Jupiter's moons between the Jovian giant and the Sun was imaged last November 10th.  The shadows of Io, Callisto, and Ganymede move across Jupiter as these moons progress in their orbits.  It was by noting the times of eclipse of Jupiter's moons in 1675 that Ole Roemer became the first person to measure the speed of light.  When a shadow from Earth's Moon crosses the Earth's surface, the people inside the shadow see an eclipse of the Sun.
A Magellanic Mural (1998-02-03)

Two galaxies stand out to casual observers in Earth's Southern Hemisphere: the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC).  These irregular galaxies are two of the closest galaxies to our Milky Way Galaxy.  Recent observations of the LMC (on the left) have determined that it is on a nearly circular orbit around our Galaxy, and have even helped in the determination of the composition of dark matter in our Galaxy. The above photograph spans 40 degrees.  Visible on the lower left of the LMC is the Tarantula Nebula (in red).  In the foreground to the right of the SMC is globular cluster 47 Tucanae, appearing here as a bright point of light.
A Passing Spaceship Views Earth (1998-02-04)

This is how Earth appeared to the passing spacecraft NEAR.  The Near Earth Asteroid Rendezvous (NEAR) spacecraft was launched from Florida, USA, planet Earth in 1996. After a quick flyby of asteroid Mathilde in June last year, NEAR passed the Earth two weeks ago on its way to asteroid 433 Eros. Visible on the above representative-color picture is the western part of Earth's Southern Hemisphere.  Prominent features include the white snow-covered Antarctica and swirling and extended cloud systems. Oceans appear blue and part of South America is visible on the right.
A Martian River Bed? (1998-02-05)

This canyon on the surface of Mars appears to have been carved by flowing water. Known as Nanedi Vallis, the terraces and channels visible within the canyon strongly suggest that a river of water once ran here. But the lack of smaller surface channels and other features argue that the valley was formed by a surface collapse. Further images of Martian valley systems will help distinguish the degree to which these processes affected the Martian surface. This image was recorded on January 8th by the Mars Global Surveyor's camera during its 87th orbit of the red planet. The area pictured is about 6 miles wide. High resolution versions of the image show features that are as small as 40 feet across.
Happy Birthday Jules Verne (1998-02-06)

Sunday marks the 170th anniversary of the birth of Jules Verne (born in Nantes, France on the 8th of February, 1828). Inspired by a lifelong fascination with machines, Verne wrote visionary works about "Extraordinary Voyages" including such terrestrial travels as Around the World in 80 Days, Journey to the Centre of the Earth, and Twenty Thousand Leagues Under the Sea. In 1865 he published the story of three adventurers who undertook a journey From the Earth to the Moon. Verne's characters rode a "projectile-vehicle" fired from a huge cannon constructed in Florida. Does that sound familiar? A century later, the Saturn V rocket and NASA's Apollo program finally turned this work of fiction into fact, propelling adventuresome trios on what was perhaps Verne's most extraordinary voyage. This stirring floodlit view shows the Apollo 9 space-vehicle atop its Saturn V. Launched from a spaceport in Florida in 1969, the Apollo 9 crew were the first to test all lunar landing hardware in space .
COBE Hotspots: The Oldest Structures Known (1998-02-07)

Above is a microwave image of the entire sky. The plane of our galaxy runs horizontally through the center. This historic all-sky map is based on the first two years of data from NASA's COsmic Background Explorer (COBE) satellite. After computer processing to remove contributions from nearby objects and the effects of the earth's motion, the map shows temperature variations in the early Universe as red "spots". These spots are the oldest, most distant structures known. As our Universe expanded and cooled, conglomerations of mass formed. The COBE images confirm that only a million years after the big-bang - which occurred roughly 15 billion years ago - parts of the universe were visibly hotter than other parts. By studying the size and distribution of the spots found with COBE and future missions, astronomers hope to learn what matter and processes caused the spots to form - and hence determine the composition, density, and future of our Universe.
M1: Filaments of the Crab Nebula (1998-02-08)

The Crab Nebula, filled with mysterious filaments, is the result of a star that exploded in 1054 AD.  This spectacular supernova explosion was recorded by Chinese and (quite probably) Anasazi Indian astronomers.  The filaments are mysterious because they appear to have less mass than expelled in the original supernova and higher speed than expected from a free explosion. In the above picture, the color indicates what is happening to the electrons in different parts of the Crab Nebula. Red indicates the electrons are recombining with protons to form neutral hydrogen, while green indicates the electrons are whirling around the magnetic field of the inner nebula. In the nebula's very center lies a pulsar: a neutron star rotating, in this case, 30 times a second.

Image credit: S. Kohle, T. Credner et al.
(AIUB)
The Witch Head Nebula (1998-02-09)

Double, double toil and trouble; Fire burn, and cauldron bubble ... Maybe Macbeth should have consulted the Witch Head Nebula. This suggestively shaped reflection nebula is associated with the bright star Rigel in the constellation Orion. More formally known as IC 2118, the Witch Head Nebula glows primarily by light reflected from Rigel.  Rigel is located about one photo-width off the image to the right. Fine dust in the nebula reflects the light.  The blue color is caused not only by Rigel's blue color but because the dust grains reflect blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers here are molecules of nitrogen and oxygen. The nebula lies about 1000 light-years away.

Image credit: G. Greaney
All of Mars (1998-02-10)

Mars Global Surveyor is photographing Mars. The robot spacecraft arrived last September and continues to use solar panel aerobraking to help maneuver it to a better orbit to survey all of Mars The above image is a reconstruction of several photographs digitally combined to simulate a single vantage point 2700 kilometers above the Martian surface.  The images were taken by the Mars Orbital Camera in wide angle mode in late December 1997. Visible features include the Valles Marineris canyon across the top, and the South Polar Cap of frozen carbon dioxide at the bottom.  Many finer features that would normally be visible are hidden by dust remaining from a planet-wide storm that subsided only three weeks before these images were recorded.
Ultra-Fast Pulsar (1998-02-11)

Pulsars are rotating neutron stars, born in the violent crucibles of supernova explosions. Like cosmic lighthouses, beams of radiation from surface hotspots sweep past our viewpoint creating pulses which reveal the rotation rates of these incredibly dense stellar corpses. The most famous pulsar of all is found in the nearby supernova remnant, the Crab Nebula. The Crab's young pulsar is fast. Rotating at 33 times a second, its radiation energizes the surrounding gaseous stellar debris.  But using archival observations from orbiting X-ray telescopes, astronomers have recently identified another "Crab-like" pulsar that is even faster. Located in the Large Magellanic Cloud (LMC), X-ray pulses from this newly discovered pulsar, in the supernova remnant N157B, indicate an even faster rotation rate - 62 times a second - making it the fastest known pulsar associated with a supernova remnant. This contoured, false color X-ray image of a portion of the LMC shows the location of N157B along with the core of the nearby hot star cluster R136, and the site of another Crab-like pulsar in SNR 0540-69.3 (rotating a mere 20 times a second). The image is about 1,500 light-years across.