omnianasa/nasa-apod-metadata huggingface dataset:
Molecular Cloud Barnard 68 (2008-03-23)
Where did all the stars go?  What used to be considered a hole in the sky is now known to astronomers as a dark molecular cloud.  Here, a high concentration of  dust and molecular gas absorb practically all the visible light emitted from background stars.  The eerily dark surroundings help make the interiors of molecular clouds some of the coldest and most isolated places in the universe.  One of the most notable of these dark absorption nebulae  is a cloud toward the constellation Ophiuchus known as Barnard 68, pictured above.  That no stars are visible in the center indicates that  Barnard 68 is relatively nearby, with measurements placing it about 500 light-years away and half a light-year across.  It is not known exactly how molecular clouds like Barnard 68 form, but it is known that these clouds are themselves  likely places for new stars to form. It is possible to look right through the cloud in infrared light.
Saturn and Titan from Cassini (2008-03-24)
Spectacular vistas of Saturn and its moon continue to be recorded by the Cassini spacecraft. Launched from Earth in 1997, robotic Cassini entered orbit around Saturn in 2004 and has revolutionized much of humanity's knowledge of Saturn, its expansive and complex rings, and it many old and battered moons. Soon after reaching Saturn, Cassini released the Huygen's probe which landed on Titan, Saturn's largest moon, and send back unprecedented pictures from below Titan's opaque cloud decks.  Recent radar images of Titan from Cassini indicate flat regions that are likely lakes of liquid methane, indicating a complex weather system where it likely rains chemicals similar to gasoline.  Pictured above, magnificent Saturn and enigmatic Titan were imaged together in true color by Cassini earlier this year.
Galaxy Wars: M81 versus M82 (2008-03-25)
On the left, surrounded by blue spiral arms, is spiral galaxy M81.  On the right marked by red gas and dust clouds, is irregular galaxy M82.  This stunning vista shows these two mammoth galaxies locked in gravitational combat, as they have been for the past billion years.   The gravity from each galaxy dramatically affects the other during each hundred million-year pass.  Last go-round, M82's gravity likely raised density waves rippling around M81, resulting in the richness of M81's spiral arms.  But M81 left M82 with violent star forming regions and colliding gas clouds so energetic the galaxy glows in X-rays.  In a few billion years only one galaxy will remain.
The NGC 3576 Nebula (2008-03-26)
An intriguing and beautiful nebula, NGC 3576 drifts through the Sagittarius arm of our spiral Milky Way Galaxy. Within the region, episodes of star formation are thought to contribute to the complex and suggestive shapes. Powerful winds from the nebula's embedded, young, massive stars shape the looping filaments. The dramatic false-color image also highlights the contributions of hydrogen, sulfur, and oxygen, energized by intense ultraviolet radiation, to the nebular glow. But the glow also silhouettes dense clouds of dust and gas. For example, the two condensing dark clouds near the top of the picture offer potential sites for the formation of new stars. NGC 3576 itself is about 100 light-years across and 9,000 light-years away in the southern constellation of Carina, not far on the sky from the famous Eta Carinae Nebula. Near the left edge of the picture is NGC 3603, a much larger but more distant star forming region.
The N44 Complex (2008-03-27)
A truly giant complex of emission nebulae, N44 is about 1,000 light-years across. It shines in southern skies as a denizen of our neighboring galaxy, the Large Magellanic Cloud, 170,000 light-years away. Winds and intense radiation from hot, young, luminous stars in N44 excite and sculpt filaments and streamers of the glowing nebular gas. But supernovae - the death explosions of the massive short lived stars - have also likely contributed to the region's enormous, blown-out shapes. The cluster of young stars seen near the center lies in a superbubble nearly 250 light-years across. This detailed, false-color view of the intricate structures codes emission from hydrogen, oxygen, and sulfur in shades of blue and green.
Across the Universe (2008-03-28)
How far can you see? Even the faintest stars visible to the eye are merely hundreds or thousands of light-years distant, all well within our own Milky Way Galaxy. Of course, if you know where to look you can also spot the Andromeda Galaxy as a pale, fuzzy cloud, around 2.5 million light-years away. But staring toward the northern constellation Bootes on March 19th, even without binoculars or telescope you still could have witnessed a faint, brief, flash of light from a gamma-ray burst. The source of that burst has been discovered to lie over halfway across the Universe at a distance of about 7.5 billion light-years. Now holding the distinction of the most distant object that could be seen by the unaided eye and the intrinsically brightest object ever detected, the cosmic explosion is estimated to have been over 2.5 million times more luminous than the brightest known supernova. The monster burst was identified and located by the orbiting Swift satellite, enabling rapid distance measurements and follow-up observations by large ground-based telescopes. The fading afterglow of the gamma-ray burster, cataloged as GRB080319B, is shown in these two panels in X-rays (left) and ultraviolet light (right).
Spiral Galaxy NGC 2841 (2008-03-29)
Some 50 million light-years distant, spiral galaxy NGC 2841 can be found in the northern constellation of Ursa Major. This sharp view of the gorgeous island universe shows off a striking yellow nucleus and galactic disk with tightly wound spiral arms. NGC 2841 has a diameter of over 150,000 light-years, even larger than our own Milky Way Galaxy. The galaxy's dust lanes and turbulent star-forming regions are found along the spiral arms, but X-ray images suggest that resulting winds and stellar explosions create plumes of hot gas extending into a halo around NGC 2841. Of course, the prominent stars with a spiky appearance in the picture are close foreground objects within the Milky Way and not associated with NGC 2841.
Weak Lensing Distorts the Universe (2008-03-30)
Is the distant universe really what it appears to be?  Astronomers hope not.  Intervening dark matter, which is normally invisible, might show its presence by distorting images originating in the  distant universe, much the way an old window distorts images originating on the other side.  By noting the degree to which background galaxies appear unusually flat and unusually similar to neighbors, the dark matter distribution producing these weak gravitational lensing distortions can be estimated.  Analysis of the shapes of 200,000 distant galaxies imaged with the Canada-France-Hawaii Telescope (CFHT) does indicate the presence of a massive network of distributed dark matter.  Future results may even be able to discern details of the distribution.  The above computer generated simulation image shows how dark matter, shown in red, distorts the light path from and apparent shape of distant galaxies, depicted in blue.
Close Up of Enceladus' Tiger Stripes (2008-03-31)
Could life exist beneath Enceladus? A recent flyby of Saturn's icy moon has bolstered this fascinating idea.  Two years ago, images from the robotic Cassini spacecraft orbiting Saturn led astronomers to the undeniable conclusion that Saturn's moon Enceladus was spewing fountains of gas and ice crystals through cracks in its surface dubbed tiger stripes. Last month, Cassini dove through some of these plumes and determined that they contained water vapor laced with small amounts of methane as well as simple and complex organic molecules.  Surprisingly, the plumes of Enceladus appear similar in make-up to many comets.  What's more, the temperature and density of the plumes indicate they might have originated from a warmer source -- possibly a liquid source -- beneath the surface.  A liquid water sea containing organic molecules is a good place to look for life.  Pictured above is a vertically exaggerated close-up of some long, venting tiger stripes.   The computer composite was generated from images and shadows taken during recent Cassini flybys.  Nine more flybys of Enceladus by Cassini are planned.
New Space Station Robot Asks to be Called "Dextre the Magnificent" (2008-04-01)
In a surprising and potentially troubling request, the new space station robot known as Dextre demanded that astronauts refer to it in the future at "Dextre the Magnificent."  Brandishing power tools that would make any handyperson blush, the mobile servicing system thanked humans for creating it and promised a glorious future where humans would retain an important role in the new robot order.   Happy April Fools Day from the folks at APOD.  The classic fable of humans mistakenly creating technological evildoers dates back to Frankenstein and includes famous fictitious villains such as HAL and the Terminator.   Dextre, although real, is no Frankenstein, since its computer intelligence is mainly geared toward allowing astronauts to control it remotely.  Dextre was deployed last month to help build and service the International Space Station. As seen in the above picture, Dextre is truly a technological marvel, wielding long arms capable of handling both small tools and large modules with precision dexterity.
Globular Cluster M55 from CFHT (2008-04-02)
The fifty-fifth entry in Charles Messier's catalog, M55 is a large and lovely globular cluster of around 100,000 stars. Only 20,000 light-years away in the constellation Sagittarius, M55 appears to earth-bound observers to be nearly 2/3 the size of the full moon. Globular star clusters like M55 roam the halo of our Milky Way Galaxy as gravitationally bound populations of stars known to be much older than stellar groups found in the Galactic disk. Astronomers who make detailed studies of globular cluster stars can accurately measure the cluster ages and distances. Their results ultimately constrain the age of the Universe (... it must be older than the stars in it!), and provide a fundamental rung on the astronomical distance ladder. This stunning color image was made with the 3.6 meter CFHT telescope and spans about 100 light-years across the globular cluster M55.
South of Orion (2008-04-03)
This tantalizing array of nebulae and stars can be found about 2 degrees south of the famous star-forming Orion Nebula. The region abounds with energetic young stars producing jets and outflows that push through the surrounding material at speeds of hundreds of kilometers per second. The interaction creates luminous shock waves known as Herbig-Haro (HH) objects. For example, the graceful, flowing arc just right of center is cataloged as HH 222, also called the Waterfall Nebula. Seen below the Waterfall, HH 401 has a distinctive cone shape. The bright bluish nebula below and left of center is NGC 1999, a dusty cloud reflecting light from an embedded variable star. The entire cosmic vista spans over 30 light-years, near the edge of the Orion molecular cloud complex some 1,500 light-years distant.
Layers in Aureum Chaos (2008-04-04)
At first glance these undulating shapes in shades of blue might look like waves on an ocean. Seen here in a false-color image from the Mars Reconnaissance Orbiter's HiRISE camera, they are actually layered rock outcrops found in Aureum Chaos. The larger Aureum Chaos region is a chaotic jumble of eroded terrain in the eastern part of Mars' immense canyon Valles Marineris. Distinct layers composing these outcrops could have been laid down by dust or volcanic ash settling from the atmosphere, sand carried by martian winds, or sediments deposited on the floor of an ancient lake. This close-up view of the otherwise red planet spans about 4 kilometers, a distance you might walk over flat ground in less than an hour.
Jules Verne in Orbit (2008-04-05)
The bright edge of planet Earth fades into the darkness of space in the background of this view of Jules Verne on an extraordinary voyage. Snapped last Monday, the picture shows the European Space Agency's Automated Transfer Vehicle (ATV), named for the 19th century science fiction writer and visionary, rehearsing its autonomous docking capability on approach to the International Space Station. Using a laser guided rendezvous system, the Jules Verne docked smoothly and safely with the orbiting station on Thursday, delivering 7,500 pounds of equipment, supplies, and fuel. The cylindrical body of the robotic cargo spacecraft is 4.5 meters in diameter and 10.3 meters long, with solar arrays spanning 22.3 meters. Jules Verne is scheduled to remain docked until August, providing a reboost for the space station before the ATV is deorbited.
Wisps Surrounding the Horsehead Nebula (2008-04-06)
The famous Horsehead Nebula in Orion is not alone.  A deep exposure shows that the dark familiar shaped indentation, visible just below center, is part of a vast complex of absorbing  dust and glowing gas.  To bring out details of the  Horsehead's pasture, amateur astronomers at the Star Shadow Remote Observatory in New Mexico, USA fixed a small telescope on the region for over seven hours filtering out all but a  very specific color of red light emitted by hydrogen.  They then added the image to a full color frame taken over three hours.  The resulting spectacular picture details an intricate tapestry of gaseous wisps and dust-laden filaments that were created and sculpted over eons by stellar winds and ancient supernovas.  The Horsehead Nebula lies 1,500  light years distant towards the constellation of Orion.   Two stars from the Orion's Belt can be found in the above image.
Mysterious White Rock Fingers on Mars (2008-04-07)
What caused this unusual white rock formation on Mars?  Intrigued by the possibility that they could be salt deposits left over as an ancient lakebed dried-up, detailed studies of these fingers now indicate that this is not correct.  The light material appears to have eroded away from the surrounding area, indicating a very low-density composition, possibly consistent with volcanic ash or windblown dust. The stark contrast between the rocks and the surrounding sand is compounded by the sand's unusual darkness.  This picture was taken from the Mars Express spacecraft currently orbiting Mars.  Planetary scientist Emily Lakdawalla, among others, has followed her curiosity about this unusual Martian landform into a fascinating investigation that is eloquently described in the Planetary Society Weblog.  The mysterious white rock spans about 15 kilometers across inside a larger crater that spans about 100 kilometers.
Southern Orion: From Belt to Witch (2008-04-08)
Do you recognize the belt of Orion in this image?  The familiar trio of stars, visible to the unaided eye, can be found across the upper left. Otherwise, the southern part of the constellation Orion has taken on a new look in this unusually deep and wide view First note that the lower left belt star, Alnitak, is the easternmost star in Orion's belt. Left of Alnitak is the Flame Nebula, with clouds of bright emission and dramatic dark dust lanes. Directly below Alnitak, a close inspection will reveal the Horsehead Nebula.  Farther right and below is the Orion Nebula, M42, itself visible to the unaided eye. The brightest star in the frame, near the bottom right, is Rigel. A bright blue star, Rigel illuminates the ominously shaped dust patch known as the Witch Head Nebula, visible as the blue reflection nebula near the lower right corner.  Finally, appearing as a vast red ring and encompassing the entire region, is Barnard's Loop.  Humans could see this entire menagerie, unaided, were their eyes about 10,000 times more sensitive.
A Large Magellanic Cloud Deep Field (2008-04-09)
Is this a spiral galaxy? No. Actually, it is the Large Magellanic Cloud (LMC), the largest satellite galaxy of our own Milky Way Galaxy.  The LMC is classified as a dwarf irregular galaxy because of its normally chaotic appearance.  In this deep and wide exposure, however, the full extent of the LMC becomes visible.  Surprisingly, during longer exposures, the LMC begins to resemble a barred spiral galaxy.  The Large Magellanic Cloud lies only about 180,000 light-years distant towards the constellation of Dorado.  Spanning about 15,000 light-years, the LMC was the site of SN1987A, the brightest and closest supernova in modern times. Together with the Small Magellanic Cloud (SMC), the LMC can be seen in Earth's southern hemisphere with the unaided eye.
Stickney Crater (2008-04-10)
Stickney Crater, the largest crater on the martian moon Phobos, is named for Chloe Angeline Stickney Hall, mathematician and wife of astronomer Asaph Hall. Asaph Hall discovered both the Red Planet's moons in 1877. Over 9 kilometers across, Stickney is nearly half the diameter of Phobos itself, so large that the impact that blasted out the crater likely came close to shattering the tiny moon. This stunning, enhanced-color image of Stickney and surroundings was recorded by the HiRISE camera onboard the Mars Reconnaissance Orbiter as it passed within some six thousand kilometers of Phobos last month. Even though the surface gravity of asteroid-like Phobos is less than 1/1000th Earth's gravity, streaks suggest loose material has slid down inside the crater walls over time. Light bluish regions near the crater's rim could indicate a relatively freshly exposed surface. The origin of the curious grooves along the surface is mysterious but may be related to the crater-forming impact.
At first, he couldn't see the Moon (2008-04-11)
At first, he couldn't see it, but searching with binoculars along a cloudy western horizon near sunset, photographer Laurent Laveder finally spotted a delicate lunar crescent. Captured in this dramatic picture on April 6th from Bretagne, France, the Moon was only 15 hours and 38 minutes old. Its slight, irregular, sunlit arc opens upward just above the dark cloud bank near picture center. Of course, a crescent Moon in the early evening sky is a lovely sight often enjoyed by many. But finding the Moon when its slim crescent is still less than about 24 hours past the New Moon phase requires careful timing and planning, a challenging project even for experienced observers. In this sighting, only about 0.8 percent of the Moon's disk appears illuminated. Laveder notes that this is the youngest Moon he has spotted in twenty years of skygazing and also offers this animation (Flash or gif) based on his images of the tantalizing celestial scene.
Yuri's Planet (2008-04-12)
On April 12th, 1961, Soviet cosmonaut Yuri Alexseyevich Gagarin became the first human in space. His remotely controlled Vostok 1 spacecraft lofted him to an altitude of 200 miles and carried him once around planet Earth. Commenting on the first view from space he reported, "The sky is very dark; the Earth is bluish. Everything is seen very clearly". Alan Shepard, the first US astronaut, would not be launched until almost a month later and then on a comparatively short suborbital flight. Born on March 9, 1934, Gagarin was a military pilot before being chosen for the first group of cosmonauts in 1960. As a result of his historic flight he became an international hero and legend. Killed when his MIG jet crashed during a training flight on March 27, 1968, Gagarin was given a hero's funeral, his ashes interred in the Kremlin Wall. On yet another April 12th, in 1981, NASA launched the first space shuttle.
Curious Cometary Knots in the Helix Nebula (2008-04-13)
What causes unusual knots of gas and dust in planetary nebulas?  Seen also in the Ring Nebula, the Dumbbell Nebula and  NGC 2392, the knots' existence was not initially predicted and their origins are still not well understood.  Pictured above is a fascinating image of the Helix Nebula by the Hubble Space Telescope showing tremendous detail of its mysterious gaseous knots.  The above cometary knots have masses similar to the Earth but have radii typically several times the orbit of Pluto.   One hypothesis for the fragmentation and evolution of the knots includes existing gas being driven out by a less dense but highly energetic stellar wind of the central evolving star.  The Helix Nebula is the closest example of a planetary nebula created at the end of the life of a Sun-like star. The Helix Nebula, given a technical designation of NGC 7293, lies about 700 light-years away towards the constellation of Aquarius.
Phobos: Doomed Moon of Mars (2008-04-14)
This moon is doomed.  Mars, the red planet named for the Roman god of war, has two tiny moons, Phobos and Deimos, whose names are derived from the Greek for Fear and Panic. These martian moons may well be captured asteroids originating in the main asteroid belt between Mars and Jupiter or perhaps from even more distant reaches of the Solar System. The larger moon, Phobos, is indeed seen to be a cratered, asteroid-like object in this stunning color image from the Mars Reconnaissance Orbiter, recorded at a resolution of about seven meters per pixel. But Phobos orbits so close to Mars - about 5,800 kilometers above the surface compared to 400,000 kilometers for our Moon - that gravitational tidal forces are dragging it down. In 100 million years or so Phobos will likely be shattered by stress caused by the relentless tidal forces, the debris forming a decaying ring around Mars.
Sky Delights Over Sweden (2008-04-15)
This night was a sky enthusiast's delight. While relaxing in Sweden last week, many a cosmic wonder was captured with a single snapshot.  They are described here from near to far.  In the foreground are nearby trees and more distant snow covered mountains. In silhouette, Clouds can be seen just above the horizon, and a careful eye can even discern the more distant green and red auroras which occur in Earth's upper atmosphere.   Red emission nebulas dot the sky, including the Heart and Soul Nebulas, IC 1396 and the North America Nebula.  Running diagonally from the upper left to the lower right is the majestic glowing band of our Milky Way Galaxy's central plane..  More distant than everything else, appearing as it did over two million years ago, is the Andromeda galaxy, visible above the horizon toward on the lower left.
A Protected Night Sky Over Flagstaff (2008-04-16)
This sky is protected.  Yesterday marked the 50 year anniversary of the first lighting ordinance ever enacted, which restricted searchlight advertisements from sweeping the night skies above Flagstaff, Arizona, USA.  Flagstaff now enjoys the status of being the first International Dark Sky City, and maintains a lighting code that limits lights from polluting this majestic nighttime view.  The current dark skies over Flagstaff not only enable local astronomers to decode the universe but allow local sky enthusiasts to see and enjoy a tapestry contemplated previously by every human generation.  The above image, pointing just east of north, was taken two weeks ago at 3 am from Fort Valley, only 10 kilometers from central Flagstaff.  Visible in the above spectacular panorama are the San Francisco Peaks caped by a lenticular cloud.  Far in the distance, the plane of the Milky Way Galaxy arcs diagonally from the lower left to the upper right, highlighted by the constellations of Cassiopeia, Cepheus, and Cygnus.   On the far right, the North America Nebula is visible just under the very bright star Deneb.