omnianasa/nasa-apod-metadata huggingface dataset:
Along the Western Veil (2019-09-19)
Delicate in appearance, these filaments of shocked, glowing gas, are draped across planet Earth's sky toward the constellation of Cygnus. They form the western part of the Veil Nebula. The Veil Nebula itself is a large supernova remnant, an expanding cloud born of the death explosion of a massive star. Light from the original supernova explosion likely reached Earth over 5,000 years ago. Blasted out in the cataclysmic event, the interstellar shock wave plows through space sweeping up and exciting interstellar material.  The glowing filaments are really more like long ripples in a sheet seen almost edge on, remarkably well separated into atomic hydrogen (red) and oxygen (blue-green) gas. Also known as the Cygnus Loop, the Veil Nebula now spans nearly 3 degrees or about 6 times the diameter of the full Moon. While that translates to over 70 light-years at its estimated distance of 1,500 light-years, this telescopic image of the western portion spans about half that distance. Brighter parts of the western Veil are recognized as separate nebulae, including The Witch's Broom (NGC 6960) along the top of this view and Pickering's Triangle (NGC 6979) below and left.
Saturn at Night (2019-09-20)
Still bright in planet Earth's night skies, good telescopic views of Saturn and its beautiful rings often make it a star at star parties. But this stunning view of Saturn's rings and night side just isn't possible from telescopes closer to the Sun than the outer planet. They can only bring Saturn's day into view. In fact, this image of Saturn's slender sunlit crescent with night's shadow cast across its broad and complex ring system was captured by the Cassini spacecraft. A robot spacecraft from planet Earth, Cassini called Saturn orbit home for 13 years before it was directed to dive into the atmosphere of the gas giant on September 15, 2017. This magnificent mosaic is composed of frames recorded by Cassini's wide-angle camera only two days before its grand final plunge. Saturn's night will not be seen again until another spaceship from Earth calls.
The Tulip in the Swan (2019-09-21)
Framing a bright emission region, this telescopic view looks out across a pretty field of stars along the plane of our Milky Way Galaxy, toward the nebula rich constellation Cygnus the Swan. Popularly called the Tulip Nebula, the reddish glowing cloud of interstellar gas and dust is also found in the 1959 catalog by astronomer Stewart Sharpless as Sh2-101. About 8,000 light-years distant and 70 light-years across the complex and beautiful nebula blossoms near the center of this composite image. Ultraviolet radiation from young energetic O stars at the edge of the Cygnus OB3 association, ionizes the atoms and powers the emission from the Tulip Nebula.
Eye Sky a Dragon (2019-09-22)
What do you see when you look into this sky? In the center, in the dark, do you see a night sky filled with stars? Do you see a sunset to the left? Clouds all around? Do you see the central band of our Milky Way Galaxy running down the middle? Do you see the ruins of an abandoned outpost on a hill? (The outpost is on Askold Island, Russia.)  Do you see a photographer with a headlamp contemplating surreal surroundings? (The image is a panorama of 38 images taken last month and compiled into a Little Planet projection.)  Do you see a rugged path lined with steps? Or do you see the eye of a dragon?
Equinox: The Sun from Solstice to Solstice (2019-09-23)
Today is an equinox, a date when day and night are equal.  Tomorrow, and every day until the next equinox, the night will be longer than the day in Earth's northern hemisphere, and the day will be longer than the night in Earth's southern hemisphere. An equinox occurs midway between the two solstices, when the days and nights are the least equal. The featured picture is a composite of hourly images taken of the Sun above Bursa, Turkey on key days from solstice to equinox to solstice. The bottom Sun band was taken during the north's winter solstice in 2007 December, when the Sun could not rise very high in the sky nor stay above the horizon very long.   This lack of Sun caused winter. The top Sun band was taken during the northern summer solstice in 2008 June, when the Sun rose highest in the sky and stayed above the horizon for more than 12 hours.  This abundance of Sun caused summer. The middle band was taken during an equinox in 2008 March, but it is the same sun band that Earthlings see today, the day of the most recent  equinox.   Browser-Enhanced APOD: Google Chrome extensions (free, user created and maintained)
Sand Dunes Thawing on Mars (2019-09-24)
What are these strange shapes on Mars?  Defrosting sand dunes. As Spring dawned on the Northern Hemisphere of Mars, dunes of sand near the pole, as pictured here in late May by ESA's ExoMars Trace Gas Orbiter, began to thaw.  The carbon dioxide and water ice actually sublime in the thin atmosphere directly to gas.  Thinner regions of ice typically defrost first revealing sand whose darkness soaks in sunlight and accelerates the thaw.  The process might even involve sandy jets exploding through the thinning ice.  By Summer, spots will expand to encompass the entire dunes.  The Martian North Pole is ringed by many similar fields of barchan sand dunes, whose strange, smooth arcs are shaped by persistent Martian winds.   Create a Distant Legacy: Send your name to Mars.
The Pelican Nebula in Gas, Dust, and Stars (2019-09-25)
The Pelican Nebula is slowly being transformed.  IC 5070, the official designation, is divided from the larger North America Nebula by a molecular cloud filled with dark dust.  The Pelican, however, receives much study because it is a particularly active mix of star formation and evolving gas clouds.  The featured picture was produced in three specific colors -- light emitted by sulfur, hydrogen, and oxygen --  that can help us to better understand these interactions.  The light from young energetic stars is slowly transforming the cold gas to hot gas, with the advancing boundary between the two, known as an ionization front, visible in bright orange on the right. Particularly dense tentacles of cold gas remain.  Millions of years from now this nebula might no longer be known as the Pelican, as the balance and placement of stars and gas will surely leave something that appears completely different.
Da Vinci Rise (2019-09-26)
An old Moon rose this morning, its waning sunlit crescent shining just above the eastern horizon before sunrise. But earthshine, light reflected from a bright planet Earth, lit the shadowed portion of the lunar disk and revealed most of a familiar lunar near side to early morning risers. In fact, a description of earthshine in terms of sunlight reflected by Earth's oceans illuminating the Moon's dark surface was written over 500 years ago by Leonardo da Vinci. One lunation ago this old Moon also rose above the eastern horizon. Its sunlit crescent and da Vinci glow were captured in stacked exposures from the Badain Jilin Desert of Inner Mongolia, China on August 29, 2019. This year marks the 500th anniversary of Leondardo da Vinci's death.
The Annotated Galactic Center (2019-09-27)
The center of our Milky Way galaxy can be found some 26,000 light-years away toward the constellation Sagittarius. Even on a dark night, you can't really see it though. Gaze in that direction, and your sight-line is quickly obscured by intervening interstellar dust. In fact, dark dust clouds, glowing nebulae, and crowded starfieds are packed along the fertile galactic plane and central regions of our galaxy. This annotated view, a mosaic of dark sky images, highlights some favorites, particularly for small telescope or binocular equipped skygazers. The cropped version puts the direction to the galactic center on the far right. It identifies well-known Messier objects like the Lagoon nebula (M8), the Trifid (M20), star cloud M24, and some of E.E. Barnard's dark markings on the sky. A full version extends the view to the right toward the constellation Scorpius, in all covering over 20 degrees across the center of the Milky Way.
An Analemma of the Sun (2019-09-28)
This week the equinox found the Sun near the middle, but not at the crossing point, of an analemma in its annual trek through planet Earth's skies. In this scenic view, that graceful, figure-8-shaped curve was intentionally posed above the iconic Danube River and the capital city of Hungary. Looking south from Budapest's Margaret Bridge it combines digital frames taken at exactly the same time of day (11:44 CET) on dates between 2018 September 24 and 2019 September 15. That puts the metropolitan Pest on the left, regal Buda on the right, and the positions of the Sun on the solstice dates at the top and bottom of the analemma curve. December's near solstice Sun is just hidden behind a dramatic cloud bank.
MyCn 18: The Engraved Hourglass Planetary Nebula (2019-09-29)
Do you see the hourglass shape -- or does it see you?  If you can picture it, the rings of MyCn 18 trace the outline of an hourglass -- although one with an unusual eye in its center.  Either way, the sands of time are running out for the central star of this hourglass-shaped planetary nebula. With its nuclear fuel exhausted, this brief, spectacular, closing phase of a Sun-like star's life occurs as its outer layers are ejected - its core becoming a cooling, fading white dwarf. In 1995, astronomers used the Hubble Space Telescope (HST) to make a series of images of planetary nebulae, including the one featured here.  Pictured, delicate rings of colorful glowing gas (nitrogen-red, hydrogen-green, and oxygen-blue) outline the tenuous walls of the hourglass. The unprecedented sharpness of the Hubble images has revealed surprising details of the nebula ejection process that are helping to resolve the outstanding mysteries of the complex shapes and symmetries of planetary nebulas like MyCn 18.
Orion Rising over Brazil (2019-09-30)
Have you seen Orion lately? The next few months will be the best for seeing this familiar constellation as it rises continually earlier in the night.  However, Orion's stars and nebulas won't look quite as colorful to the eye as they do in this fantastic camera image. In the featured image, Orion was captured by camera showing its full colors last month over a Brazilian copal tree from Brazil's Central-West Region. Here the cool red giant Betelgeuse takes on a strong orange hue as the brightest star on the far left. Otherwise, Orion's hot blue stars are numerous, with supergiant Rigel balancing Betelgeuse at the upper right, Bellatrix at the upper left, and Saiph at the lower right. Lined up in Orion's belt (bottom to top) are Alnitak, Alnilam, and Mintaka all about 1,500 light-years away, born of the constellation's well studied interstellar clouds. And if a "star" toward the upper right  Orion's sword looks reddish and fuzzy to you, it should. It's the stellar nursery known as the Great Nebula of Orion.
Molecular Clouds in the Carina Nebula (2019-10-02)
They are not alive -- but they are dying. The unusual forms found in the Carina nebula, a few of which are featured here, might best be described as evaporating. Energetic light and winds from nearby stars are breaking apart the dark dust grains that make the iconic forms opaque. Ironically the figures, otherwise known as dark molecular clouds or bright rimmed globules, frequently create in their midst the very stars that later destroy them.  The floating space structures pictured here by the orbiting Hubble Space Telescope span a few light months. The Great Nebula in Carina itself spans about 30 light years, lies about 7,500 light years away, and can be seen with a small telescope toward the constellation of Keel(Carina).
The Hydrogen Clouds of M33 (2019-10-03)
Gorgeous spiral galaxy M33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies a mere 3 million light-years away.  The galaxy's inner 30,000 light-years or so are shown in this magnificent 25 panel telescopic mosaic. Based on image data from space and ground-based telescopes, the portrait of M33 shows off the galaxy's reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33's giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. To enhance this image, broadband data were used to produce a color view of the galaxy and combined with narrowband data recorded through a hydrogen-alpha filter. That filter transmits the light of the strongest visible hydrogen emission line.
InSight on a Cloudy Day (2019-10-04)
Clouds drift through the sky as the light fades near sunset in this three frame animated gif. The scene was captured on sol 145 beginning around 6:30pm local time by a camera on the Mars InSight lander. Of course, InSight's martian day, sol 145, corresponds to Earth calendar date April 25, 2019. Under the 69 centimeter (2.3 foot) diameter dome in the foreground is the lander's sensitive seismometer SEIS designed to detect marsquakes. Earthquakes reveal internal structures on planet Earth, and so tremors detected by SEIS can explore beneath the martian surface. In particular, two typical marsquakes were recorded by SEIS on May 22 (sol 173) and July 25 (sol 235). The subtle tremors from the Red Planet are at very low frequencies though, and for listening have to be processed into the audio frequency range. In the sped up recordings external noises more prevalent on cool martian evenings and likely caused by mechanical shifts and contractions have been technically dubbed dinks and donks.
Jupiter and the Moons (2019-10-05)
After sunset on October 3, some of the Solar System's largest moons stood low along the western horizon with the largest planet. Just after nightfall, a pairing of the Moon approaching first quarter phase and Jupiter was captured in this telephoto field of view. A blend of short and long exposures, it reveals the familiar face of our fair planet's own large natural satellite in stark sunlight and faint earthshine. At lower right are the ruling gas giant and its four Galilean moons. Left to right, the tiny pinpricks of light are Ganymede, [Jupiter], Io, Europa, and Callisto. Our own natural satellite appears to loom large because it's close, but Ganymede, Io, and Callisto are actually larger than Earth's Moon. Water world Europa is only slightly smaller. Of the Solar System's six largest planetary satellites, only Saturn's moon Titan, is missing from this scene. But be sure to check for large moons in your sky tonight.   Tonight: International Observe the Moon Night  Submitted to APOD: The Moon and Jupiter with its Satellites
The Horsehead Nebula (2019-10-06)
The Horsehead Nebula is one of the most famous nebulae on the sky.  It is visible as the dark indentation to the red emission nebula in the center of the above photograph.  The horse-head feature is dark because it is really an opaque dust cloud that lies in front of the bright red emission nebula. Like clouds in Earth's atmosphere, this cosmic cloud has assumed a recognizable shape by chance.  After many thousands of years, the internal motions of the cloud will surely alter its appearance.  The emission nebula's red color is caused by electrons recombining with protons to form hydrogen atoms.  On the image left is the Flame Nebula, an orange-tinged nebula that also contains filaments of dark dust. Just to the lower left of the Horsehead nebula featured picture is a blueish reflection nebulae that preferentially reflects the blue light from nearby stars.
Io Eclipse Shadow on Jupiter from Juno (2019-10-07)
What's that dark spot on Jupiter? It's the shadow of Jupiter's most volcanic moon Io. Since Jupiter shines predominantly by reflected sunlight, anything that blocks that light leaves a shadow.  If you could somehow be in that shadow, you would see a total eclipse of the Sun by Io.  Io's shadow is about 3600 kilometers across, roughly the same size as Io itself -- and only slightly larger than Earth's Moon. The featured image was taken last month by NASA's robotic Juno spacecraft currently orbiting Jupiter. About every two months, Juno swoops close by Jupiter, takes a lot of data and snaps a series of images -- some of which are made into a video. Among many other things, Juno has been measuring Jupiter's gravitational field, finding surprising evidence that Jupiter may be mostly a liquid. Under unexpectedly thick clouds, the Jovian giant may house a massive liquid hydrogen region that extends all the way to the center.
Sprite Lightning in HD (2019-10-08)
This phenomenon occurs in the sky over our heads, not the sea.  It is a type of lightning known as red sprite, and rarely has it ever been photographed in this detail.  Even though sprites have been recorded for over 30 years, their root cause remains unknown.  Some thunderstorms have them, but most don't. These mysterious bursts of light in the upper atmosphere momentarily resemble gigantic jellyfish. A few years ago high speed videos were taken detailing how red sprites actually develop.  The featured image was captured last month in high definition from Italy.  One unusual feature of sprites is that they are relatively cold -- they operate more like long fluorescent light tubes than hot compact light bulbs.  In general, red sprites take only a fraction of a second to occur and are best seen when powerful thunderstorms are visible from the side.
NGC 7714: Starburst after Galaxy Collision (2019-10-09)
Is this galaxy jumping through a giant ring of stars?  Probably not.  Although the precise dynamics behind the featured image is yet unclear, what is clear is that the pictured galaxy, NGC 7714, has been stretched and distorted by a recent collision with a neighboring galaxy. This smaller neighbor, NGC 7715, situated off to the left of the featured frame, is thought to have charged right through NGC 7714. Observations indicate that the golden ring pictured is composed of millions of older Sun-like stars that are likely co-moving with the interior bluer stars. In contrast, the bright center of NGC 7714 appears to be undergoing a burst of new star formation.  The featured image was captured by the  Hubble Space Telescope.  NGC 7714 is located about 130 million light years away toward the constellation of the Two Fish (Pisces).  The interactions between these galaxies likely started about 150 million years ago and should continue for several hundred million years more, after which a single central galaxy may result.
Mid-Air Meteor and Milky Way (2019-10-10)
On September 24, a late evening commercial flight from Singapore to Australia offered stratospheric views of the southern hemisphere's night sky, if you chose a window seat. In fact, a well-planned seating choice with a window facing toward the Milky Way allowed the set up of a sensitive digital camera on a tripod mount to record the galaxy's central bulge in a series of 10 second long exposures.  By chance, one of the exposures caught this bright fireball meteor in the starry frame. Reflected along the wing of the A380 aircraft, the brilliant greenish streak is also internally reflected in the double layer window, producing a fainter parallel to the original meteor track. In the southern sky Jupiter is the bright source beneath the galactic bulge and seen next to a green beacon, just off the wing tip.
Planet Earth at Blue Hour (2019-10-11)
Nature photographers and other fans of planet Earth always look forward to the blue hour. That's the transition in twilight, just before sunrise or after sunset, when the Sun is below the horizon but land and sky are still suffused with beautiful bluish hues of light. On August 8 this early morning blue hour panorama scanned along the clear western sky, away from the impending sunrise. A breathtaking scene, it looks down the slopes of Mt. Whitney, from along the John Muir Trail toward rugged peaks of planet Earth's Sierra Nevada mountain range. Above the horizon a faint pinkish band of back scattered sunlight, the anti-twilight arch or Belt of Venus, borders the falling grey shadow of Earth itself. Subtle bands of light across the clear sky are anti-crepuscular rays, defined by shadows of clouds near the sunward horizon. Actually following parallel lines they seem to converge along the horizon at the point opposite the rising Sun due to perspective.
Interplanetary Earth (2019-10-12)
In an interplanetary first, on July 19, 2013 Earth was photographed on the same day from two other worlds of the Solar System, innermost planet Mercury and ringed gas giant Saturn. Pictured on the left, Earth is the pale blue dot just below the rings of Saturn, as captured by the robotic Cassini spacecraft then orbiting the outermost gas giant. On that same day people across planet Earth snapped many of their own pictures of Saturn. On the right, the Earth-Moon system is seen against the dark background of space as captured by the robotic MESSENGER spacecraft, then in Mercury orbit. MESSENGER took its image as part of a search for small natural satellites of Mercury, moons that would be expected to be quite dim. In the MESSENGER image, the Earth (left) and Moon (right) are overexposed and shine brightly with reflected sunlight. Destined not to return to their home world, both Cassini and MESSENGER have since retired from their missions of Solar System exploration.
A Stellar Jewel Box: Open Cluster NGC 290 (2019-10-13)
Jewels don't shine this bright -- only stars do.  Like gems in a jewel box, though, the stars of open cluster NGC 290 glitter in a beautiful display of brightness and color.   The photogenic cluster, pictured here, was captured in 2006 by the orbiting Hubble Space Telescope.  Open clusters of stars are younger, contain few stars, and contain a much higher fraction of blue stars than do globular clusters of stars.  NGC 290 lies about 200,000  light-years distant in a neighboring galaxy called the Small Cloud of Magellan (SMC).   The open cluster contains hundreds of stars and spans about 65 light years across.  NGC 290 and other open clusters are good laboratories for studying how stars of different masses evolve, since all the open cluster's stars were born at about the same time.
Andromeda before Photoshop (2019-10-14)
What does the Andromeda galaxy really look like? The featured image shows how our Milky Way Galaxy's closest major galactic neighbor really appears in a long exposure through Earth's busy skies and with a digital camera that introduces normal imperfections.  The picture is a stack of 223 images, each a 300 second exposure, taken from a garden observatory in Portugal over the past year.  Obvious image deficiencies include bright parallel airplane trails, long and continuous satellite trails, short cosmic ray streaks, and bad pixels.  These imperfections were actually not removed with Photoshop specifically, but rather greatly reduced with a series of computer software packages that included Astro Pixel Processor, DeepSkyStacker, and PixInsight.  All of this work was done not to deceive you with a digital fantasy that has little to do with the real likeness of the Andromeda galaxy (M31), but to minimize Earthly artifacts that have nothing to do with the distant galaxy and so better recreate what M31 really does look like.