juliensimon/nasa-apod huggingface dataset:
Comet Churyumov-Gerasimenko Creates Its Tails (2025-10-19)

Where do comet tails come from?  There are usually no obvious places on the nuclei of comets from which the jets that create comet tails emanate.  One of the best images of emerging jets is shown in the featured picture, taken in 2015 by ESA's robotic Rosetta spacecraft that orbited Comet 67P/Churyumov-Gerasimenko (Comet CG) from 2014 to 2016.  The picture shows plumes of gas and dust escaping numerous places from Comet CG's nucleus as it neared the Sun and heated up.  The comet has two prominent lobes, the larger one spanning about 4 kilometers, and a smaller 2.5-kilometer lobe connected by a narrow neck. Analyses indicate that evaporation must be taking place well inside the comet's surface to create the jets of gas, dust, and ice that we see emitted through the surface.  Comet CG (also known as Comet 67P) loses in jets about a meter of surface depth during each of its 6.44-year orbits around the Sun, a rate at which will completely destroy the comet in only thousands of years. In 2016, Rosetta's mission ended with a controlled impact onto Comet CG's surface.
Finding Comet Lemmon (2025-10-20)

Tonight, if you can see the stars of the Big Dipper, then you can find comet Lemmon in your evening sky.  After sunset, look for the faint but extended comet above your northwestern horizon -- but below the handle of the famous celestial kitchen utensil of the north. It might be easier to see this visitor to the inner Solar System through your camera phone, which is better at picking up faint objects.  Either way, look for a fuzzy green 'star' with a tail, though probably not so long a tail as in this impressive snapshot taken over Seč Lake in the Czech Republic two nights ago. Recent photographs of C/2025 A6 (Lemmon) often show a detailed and changing ion tail which extends farther than the eye can follow.  This Sun-orbiting comet is now near its closest approach to Earth  and will pass its closest to the Sun in early November.

Image credit: Petr Horalek /
Institute of Physics in Opava
IC 1805: The Heart Nebula (2025-10-21)

What electrifies the Heart Nebula? First, the large emission nebula on the left, catalogued as IC 1805, looks somewhat like a human heart.  The nebula glows brightly in red light emitted by its most prominent element, hydrogen, but this long-exposure image was also blended with light emitted by sulfur (yellow) and oxygen (blue).  In the center of the Heart Nebula are young stars from the open star cluster Melotte 15 that are eroding away several picturesque dust pillars with their atom-exciting energetic light and winds. The Heart Nebula is located about 7,500 light years away toward the constellation of Cassiopeia.  At the top right of the Heart Nebula is the companion Fishhead Nebula.  This wide and deep image clearly shows that glowing gas surrounds the Heart Nebula in all directions.

Image credit: Toni Fabiani
Comet Lemmon over the High Tatras (2025-10-22)

Comet Lemmon putting on a show for cameras around the globe. Passing nearest to the Earth this week, the photogenic comet C/2025 A6 (Lemmon) is now extending two long tails : a blue ion tail and a white dust tail. The ion tail is pushed away from the Sun by the ever-present by ever-changing solar wind, and shows structure also created by how much gas is ejected at any one moment.  It glows because it is ionized by high energy sunlight.  The dust tail is pushed away from the comet by sunlight and shines by reflecting sunlight.  The featured image is an enhanced composite of 50 exposures all taken two days ago from Mlynica, Slovakia. The mountains in the foreground are the High Tatras that partly separate Slovakia from Poland.  Although Comet Lemmon is best visible in long camera exposures, the shedding ice ball has become faintly visible in northern skies even to unaided eyes through dark skies toward the west after sunset.

Image credit: Tomáš Slovinský & 
Constantine Themelis
SWAN, Swan, Eagle (2025-10-23)

Comet C/2025 R2 (SWAN) sports a greenish coma and fainter tail, seen against congeries of stars and dusty interstellar clouds in this 7 degree wide telescopic field of view from October 17. On that date, the new visitor to the inner Solar System obligingly posed with two other celestial birds seen toward the center of our Milky Way. Messier 16, near the bottom of the frame, and Messier 17 are also known to deep skywatchers as the Eagle and the Swan nebulae. While the comet coma's greenish glow recorded in the image is due to diatomic carbon gas fluorescing in sunlight, reddish hues seen in the nebulae, star forming regions some 5,000 light-years distant, are characteristic of ionized hydrogen gas. Comet SWAN is outbound now but still a good comet for binoculars and small telescopes that can look close to the southern horizon in the northern hemisphere's early evening skies. C/2025 R2 (SWAN) was closest to our fair planet on October 20, a mere 2.2 light-minutes away.

Image credit: Adam Block
Saturn at Night (2025-10-24)

Saturn is bright in Earth's night skies. Telescopic views of the outer gas giant planet 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 in the vicinity of planet Earth. Peering out from the inner Solar System they can only bring Saturn's day side 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.
Webb's Rho Ophiuchi (2025-10-25)

A mere 390 light-years away, Sun-like stars and future planetary systems are forming in the Rho Ophiuchi molecular cloud complex, the closest star-forming region to our fair planet. The James Webb Space Telescope's NIRCam peered into the nearby natal chaos to capture this infrared image at an inspiring scale. The frame spans less than a light-year across the Rho Ophiuchi region and contains about 50 young stars. Brighter stars clearly show Webb's characteristic pattern of diffraction spikes. Huge jets of shocked molecular hydrogen blasting from newborn stars are red in the image, with the large, yellowish dusty cavity carved out by the energetic young star near its center. Near some stars in the stunning image are shadows cast by their protoplanetary disks. The spectacular cosmic snapshot was released in 2023 to celebrate the successful first year of Webb's exploration of the Universe.
Halloween and the Ghost Head Nebula (2025-10-26)

Halloween's origin is ancient and astronomical.  Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere).  With a modern calendar however, even though Halloween is later this week, the real cross-quarter day will occur the next week.  Another cross-quarter day is Groundhog Day. Halloween's modern celebration retains historic roots in dressing to scare away the spirits of the dead.  Perhaps a fitting tribute to this ancient holiday is this view of the Ghost Head Nebula taken with the Hubble Space Telescope.  Similar to the icon of a fictional ghost, NGC 2080 is actually a star forming region in the Large Magellanic Cloud, a satellite galaxy of our own Milky Way Galaxy.  The Ghost Head Nebula (NGC 2080) spans about 50 light-years and is shown in representative colors.
Two Tails of Comet Lemmon (2025-10-27)

How many bright tails does Comet Lemmon have? Two.  In the featured image it appears to have three, but why?  The reason is that the zigzagging brown filament is a persistent meteor train that by luck appeared in front of the distant comet C/2025 A6 (Lemmon).  A meteor train is the hot gas and fine dust that remains in the Earth's atmosphere and disperses in the seconds after a bright meteor flashes by.  The two bright tails are the blue ion tail stretching across the image, and the white dust tail nearer the green coma on the upper left. All real comet tails originate from the nucleus of the comet inside the coma. The image was captured a few days ago from Manciano, Italy.  This week, from mid-northern locations, Comet Lemmon will remain faintly visible in the northwest sky after sunset.
NGC 6995: The Bat Nebula (2025-10-28)

Can you see the bat?  It haunts this cosmic close-up of the eastern Veil Nebula.  The Veil Nebula itself is a large supernova remnant, the expanding debris cloud from the death explosion of a massive star. While the Veil is roughly circular in shape and covers nearly 3 degrees on the sky toward the constellation of the Swan (Cygnus), NGC 6995, known informally as the Bat Nebula, spans only 1/2 degree, about the apparent size of the Moon. That translates to 12 light-years at the Veil's estimated distance, a reassuring 1,400 light-years from planet Earth. In the composite of image data recorded through several narrow band filters, emission from hydrogen atoms is shown in red and strong emission from oxygen atoms is shown in hues of blue. Of course, in the western part of the Veil lies another seasonal apparition: the Witch's Broom Nebula.

Image credit: Francis Bozon-Gangloff
Dust Shapes of the Ghost Nebula (2025-10-29)

Do any shapes seem to jump out at you from this interstellar field of stars and dust?  The jeweled expanse, filled with faint, starlight-reflecting clouds, drifts through the night in the royal constellation of Cepheus. Far from your own neighborhood on planet Earth, these ghostly apparitions lurk along the plane of the Milky Way at the edge of the Cepheus Flare molecular cloud complex some 1,200 light-years away. Over two light-years across and brighter than the other spooky chimeras, VdB 141 or Sh2-136 is also known as the Ghost Nebula, seen across the middle of the featured image. Within the reflection nebula are the telltale signs of dense cores collapsing in the early stages of star formation.

Image credit: Kent Wood
Lynds Dark Nebula 43 (2025-10-30)

Sure, Halloween is an astronomy holiday. But astronomers always enjoy scanning the heavens for spook-tacular galaxies, stars, and nebulae. This favorite is item number 43 from the Beverly Lynds 1962 Catalog of Dark Nebulae, fondly known as the Cosmic Bat nebula. While its visage looks alarmingly like a scary flying mammal, Lynds Dark Nebula 43 is over 12 light-years across. Glowing with eerie light, stars are forming within the dusty interstellar molecular cloud that is dense enough to appear in silhouette against a luminous background of Milky Way stars. Watch out. This Cosmic Bat nebula is a mere 400 light-years distant toward the serpent-bearing constellation Ophiucus.

Image credit: Team Ciel Austral
Ghosts in Cassiopeia (2025-10-31)

Halloween is an astronomy holiday and spooky shapes always seem to lurk in planet Earth's night skies. In fact, near the center of this telescopic view toward the constellation Cassiopeia these swept-back interstellar clouds IC 59 (left) and IC 63 look ghostly on a cosmic scale. About 600 light-years distant, the clouds aren't actually ghosts. They are slowly disappearing though, under the influence of energetic radiation from hot, luminous star gamma Cas. The brightest bluish star in the frame, Gamma Cas is physically located only 3 to 4 light-years from the nebulae. Slightly closer to gamma Cas, IC 63 is dominated by red H-alpha light emitted as hydrogen atoms ionized by the hot star's ultraviolet radiation recombine with electrons. Farther from the star IC 59 also shows H-alpha emission, and both nebulae shine with the characteristic blue tint of dust reflected star light. The field of view spans about 2 degrees or 20 light-years at the estimated distance of the interstellar apparitions.

Image credit: Alex Rodriguez
Pleiades from Planet Earth (2025-11-01)

The lovely Pleiades star cluster shines in Earth's night sky, a compact group of stars some 400 light-years distant toward the constellation Taurus and the Orion Arm of our Milky Way galaxy. Recognized since ancient times, the remarkable celestial gathering is visible to the unaided eye. The Pleiades cluster is also well-placed for viewing from both northern and southern hemispheres, and over the centuries has become connected to many cultural traditions and celebrations, including the cross-quarter day celebration Halloween. In Greek myth, the Pleiades were seven daughters of the astronomical titan Atlas and sea-nymph Pleione. Galileo first sketched the star cluster viewed through his telescope with stars too faint to be seen by eye and Charles Messier recorded the position of the cluster as the 45th entry in his well-known catalog of things which are not comets. In this dramatic night skyscape from planet Earth, the stars of the Pleiades appear embedded in dusty blue reflection nebulae, poised above Mt Sefton, one of the tallest peaks in New Zealand. There known as Matariki, the star cluster is associated with the celebration of the Maori new year.

Image credit: Max Inwood
A Horseshoe Einstein Ring from Hubble (2025-11-02)

What's large and blue and can wrap itself around an entire galaxy? A gravitational lens mirage. Pictured here,  the gravity of a massive elliptical galaxy (luminous red galaxy: LRG) has gravitationally distorted the light from a much more distant blue galaxy. More typically, such light bending results in two discernible images of the distant galaxy, but here the lens alignment is so precise that the background galaxy is distorted into a horseshoe -- a nearly complete ring: an Einstein ring.  Although LRG 3-757 was discovered in 2007 in data from the  Sloan Digital Sky Survey (SDSS), the image shown above is a follow-up observation taken with the Hubble Space Telescope's  Wide Field Camera 3. A recent lens analysis of the central galaxy indicates that it likely hosts the single most massive black hole yet discovered: 36 billion times the mass of our Sun.
A Double Helix Lunar Eclipse (2025-11-03)

The image was timed to capture a total lunar eclipse -- but it came with quite a twist.  First, the eclipse: the fully Earth-shadowed Moon is visible as the orange orb near the top. The eclipsed Moon's orange color is caused by a slight amount of red light scattered first by Earth's atmosphere, adding a color like a setting Sun. Now, the twist: one of the apparent double helix bands is the Milky Way, the central disk of our home galaxy. The second band is zodiacal light, sunlight scattered by dust in our Solar System. The reason they cross is because the plane where dust orbits our Sun is tilted relative to the plane where stars orbit our Galaxy. This well-known tilt is shown dramatically in the featured wide-angle Mercator-projected picture, spanning from horizon to horizon, captured in early September from Mingantu Observing Station in Inner Mongolia, China.

Image credit: Chunlin Liu
Comet Lemmon Beyond Lomnický Peak (2025-11-04)

Comet Lemmon has been putting on a show for cameras around the globe.  Passing nearest to Earth in late October, the photogenic comet C/2025 A6 (Lemmon) sprouted two long and picturesque tails: a blue ion tail and a white dust tail.  The ion tail is pushed away from the coma by the ever-present but ever-changing solar wind, at one point extending over 20 times the diameter of the full Moon -- as captured in this long-duration exposure.  The shorter and wider dust tail is pushed away from the coma and shines by reflecting sunlight.  The featured picture, captured two weeks ago, framed the comet behind Lomnický Peak of the High Tatra Mountains, home to the Slovakian Lomnický Stit Observatory.  Comet Lemmon is now fading as it heads away from planet Earth.  The huge shedding snowball will round the Sun later this week.

Image credit: Robert Barsa
Spiral Galaxy NGC 3370 from Hubble (2025-11-05)

Is this what our own Milky Way Galaxy looks like from far away? Similar in size and grand design to our home Galaxy (although without the central bar), spiral galaxy NGC 3370 lies about 100 million light-years away toward the constellation of the Lion (Leo).  Recorded here in exquisite detail by the Hubble Space Telescope, the big, beautiful face-on spiral is not only photogenic, but has proven sharp enough to study individual stars known as Cepheids. These pulsating stars have been used to accurately determine NGC 3370'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 supernovas at even greater distances has helped to reveal the size and expansion rate of the entire Universe itself.
NGC 253: Dusty Island Universe (2025-11-06)

Shiny NGC 253 is one of the brightest spiral galaxies visible, and also one of the dustiest.  Some call it the Silver Coin Galaxy for its appearance in small telescopes, or just the Sculptor Galaxy for its location within the boundaries of the southern constellation Sculptor.  Discovered in 1783 by mathematician and astronomer Caroline Herschel, the dusty island universe lies a mere 10 million light-years away. About 70 thousand light-years across, NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest to our own Local Group of Galaxies.  In addition to its spiral dust lanes, tendrils of dust seem to be rising from its galactic disk laced with young star clusters and star forming regions in this colorful galaxy portrait. The high dust content accompanies frantic star formation, earning NGC 253 the designation of a starburst galaxy. NGC 253 is also known to be a strong source of high-energy x-rays and gamma rays, likely due to black holes near the galaxy's center.

Image credit: Adam Block
A Dark Seahorse in Cepheus (2025-11-07)

Spanning light-years, this suggestive shape known as the Seahorse Nebula floats in silhouette against a rich background of stars and glowing hydrogen gas. Seen toward the royal northern constellation of Cepheus, the dusty, dark nebula is part of a Milky Way molecular cloud some 1,200 light-years distant. It is also listed as Barnard 150 (B150), one of 182 dark markings of the sky cataloged in the early 20th century by astronomer E. E. Barnard. Packs of low mass stars are forming within, but their collapsing cores are only visible at long infrared wavelengths. Still, the luminous depths of the Milky Way in Cepheus add to this stunning galactic skyscape.

Image credit: Jordi Jofre
A Full Moon at Perigee (2025-11-08)

What is big, bright, and beautiful, can wear a cape made of clouds, and is at the closest point in its elliptical orbit around planet Earth? A full moon at perigee of course, captured here near moonset in predawn skies on November 5 from Kayseri, Turkiye. Full moons that happen at (or very near) perigee, and so are slightly larger and brighter than full moons on average, have become popularly known as supermoons. In fact, this full moon at perigee is the closest and brightest of the three supermoons of 2025. Rising as the Sun sets, this full moon follows this October's Harvest Moon and is traditionally known to some as the Hunter's Moon.

Image credit: Betul Turksoy
Road to the Galactic Center (2025-11-09)

Does the road to our galaxy's center go through Monument Valley? It doesn't have to, but if your road does -- take a picture. In this case, the road is US Route 163 and iconic buttes on the Navajo National Reservation populate the horizon.  The band of Milky Way Galaxy stretches down from the sky and appears to be a continuation of the road on Earth. Filaments of dust darken the Milky Way, in contrast to billions of bright stars and several colorful glowing gas clouds including the Lagoon and Trifid nebulas. The featured picture is a composite of images taken with the same camera and from the same location -- Forrest Gump Point in Utah, USA. The foreground was taken just after sunset in early 2021 September during the blue hour, while the background is a mosaic of four exposures captured a few hours later.

Image credit: Michael Abramyan
Micro Moon vs. Super Moon (2025-11-10)

What was so super about Wednesday's supermoon?  Last week, a full moon occurred that appeared slightly larger and brighter than usual.  The reason is that the Moon's fully illuminated phase occurred within a short time from perigee - when the Moon was its closest to the Earth in its elliptical orbit.  Although the precise conditions that define a supermoon vary, last Wednesday's supermoon was surely the closest, largest, and brightest full moon this year.  One reason supermoons are popular is because they are so easy to see -- just go outside at sunset and watch an impressive full moon rise!  Pictured here, Wednesday's supermoon is compared to April's micro moon -- when a full Moon occurs near the furthest part of the Moon's orbit -- so that it appears slightly smaller and dimmer than usual.  Given many definitions, at least one supermoon occurs each year, with another one coming next month (moon-th).

Image credit: Şenol Şanlı"
Jupiter in Ultraviolet from Hubble (2025-11-11)

Jupiter looks a bit different in ultraviolet light.  To better interpret  Jupiter's cloud motions and to help NASA's robotic Juno spacecraft understand the planetary context of the small fields that it sees, the Hubble Space Telescope was being directed to regularly image the entire Jovian giant. The colors of Jupiter being monitored go beyond the normal human visual range to include both ultraviolet and (not pictured) infrared light.  Featured from 2017, Jupiter appears different in near ultraviolet light, partly because the amount of sunlight reflected back is distinct, giving differing cloud heights and latitudes discrepant brightnesses. In the near UV, Jupiter's poles appear relatively dark, as does its Great Red Spot and a smaller (optically) white oval to the right.  The String of Pearl storms farther to the right, however, are brightest in near ultraviolet, and so here appear (false-color) pink.  Jupiter's largest moon Ganymede appears on the upper left. Juno continues on a looping 33-day orbit around Jupiter, while Earth-orbiting Hubble is aging and now relies on a single stabilizing gyroscope.
A Super Lunar Corona (2025-11-12)

What are those colorful rings around the Moon?  A corona.  Rings like this will sometimes appear when the Moon is seen through thin clouds.  The effect is created by the diffraction of light around individual, similarly-sized water droplets in an intervening but mostly transparent cloud.  Since light of different colors has different wavelengths, each color diffracts differently.  Lunar coronae are one of the few color  diffraction effects that can be easily seen with the unaided eye.  The featured image of a lunar corona was captured around last week's full Super Moon from near Knight's Ferry, California, USA.  To the right of the full Moon is the giant orange star Botein.  Similar coronae that form around the Sun are typically harder to see because of the Sun's great brightness.

Image credit: Eric Houck