juliensimon/nasa-apod huggingface dataset:
GW250114: Rotating Black Holes Collide (2025-09-24)

It was the strongest gravitational wave signal yet measured -- what did it show?  GW250114 was detected by both arms of the Laser Interferometer Gravitational-wave Observatory (LIGO) in Washington and Louisiana USA earlier this year.  Analysis showed that the event was created when two black holes, each of mass around 33 times the mass of the Sun, coalesced into one larger black hole with a mass of around 63 solar masses.  Even though the event happened about a billion light years away, the signal was so strong that the spin of all black holes, as well as initial ringing of the final black hole, was deduced with exceptional accuracy. Furthermore, it was confirmed better than before, as previously predicted, that the total event horizon area of the combined black hole was greater than those of the merging black holes. Featured, an artist's illustration depicts an imaginative and conceptual view from near one of the black holes before collision.
Saturn Opposite the Sun (2025-09-25)

This year Saturn was at opposition on September 21, opposite the Sun in planet Earth's sky. At its closest to Earth, Saturn was also at its brightest of the year, rising as the Sun set and shining above the horizon all night long among the fainter stars of the constellation Pisces. In this snapshot from the Qinghai Lenghu Observatory, Tibetan Plateau, southwestern China, the outer planet is immersed in a faint, diffuse oval of light known as the gegenschein or counter glow. The diffuse gegenschein is produced by sunlight backscattered by interplanetary dust along the Solar System's ecliptic plane, opposite the Sun in planet Earth's sky. Like a giant eye, on this dark night Saturn and gegenschein seem to stare down on the observatory's telescope domes from their antisolar perspective. Strong atmospheric airglow forms a colorful background along the horizon.

Image credit: Jin Wang
A SWAN, an ATLAS, and Mars (2025-09-26)

A new visitor to the inner Solar System, comet C/2025 R2 (SWAN) sports a long ion tail extending diagonally across this almost 7 degree wide telescopic field of view recorded on September 21. A fainter fellow comet also making its inner Solar System debut, C/2025 K1 (ATLAS), can be spotted above and left of SWAN's greenish coma, just visible against the background sea of stars in the constellation Virgo. Both new comets were only discovered in 2025 and are joined in this celestial frame by ruddy planet Mars (bottom), a more familiar wanderer in planet Earth's night skies. The comets may appear to be in a race, nearly neck and neck in their voyage through the inner Solar System and around the Sun. But this comet SWAN has already reached its perihelion or closest approach to the Sun on September 12 and is now outbound along its orbit. This comet ATLAS is still inbound though, and will make its perihelion passage on October 8.

Image credit: Adam Block
A Rocket in the Sun (2025-09-27)

On the morning of September 24 a rocket crosses the bright solar disk in this long range telescopic snapshot captured from Orlando, Florida. That's about 50 miles west of its Kennedy Space Center launch site. This rocket carried three new space weather missions to space. Signals have now been successfully acquired from all three - NASA's Interstellar Mapping and Acceleration Probe, NASA’s Carruthers Geocorona Observatory, and the National Oceanic and Atmospheric Administration (NOAA) Space Weather Follow-On Lagrange 1 (SWFO-L1) - as they begin their journey to L1, an Earth-Sun lagrange point. L1 is about 1.5 million kilometers in the sunward direction from planet Earth. Appropriately, major space weather influencers, aka dark sunspots in active regions across the Sun, are posing with the transiting rocket. In fact, large active region AR4225 is just right of the rocket's nose.

Image credit: Pascal Fouquet
Leopard Spots on Martian Rocks (2025-09-28)

What is creating these unusual spots? Light-colored spots on Martian rocks, each surrounded by a dark border, were discovered last year by NASA's Perseverance Rover currently exploring Mars.  Dubbed leopard spots because of their seemingly similarity to markings on famous Earth-bound predators, these curious patterns are being studied with the possibility they were created by ancient Martian life.  The pictured spots measure only millimeters across and were discovered on a larger rock named Cheyava Falls.  The exciting but unproven speculation is that long ago, microbes generated energy with chemical reactions that turned rock from red to white while leaving a dark biosignature ring, like some similarly appearing spots on Earth rocks. Although other non-biological explanations have not been ruled out,  speculation focusing on this potential biological origin is causing much intrigue.
Two Camera Comets in One Sky (2025-09-29)

It may look like these comets are racing, but they are not. Comets C/2025 K1 ATLAS (left) and C/2025 R2 SWAN (right) appeared near each other by chance last week in the featured image taken from France's Reunion Island in the southern Indian Ocean.  Fainter Comet ATLAS is approaching our Sun and will reach its closest approach in early October when it is also expected to be its brightest -- although still only likely visible with long exposures on a camera.  The brighter comet, nicknamed SWAN25B, is now headed away from our Sun, although its closest approach to Earth is expected in mid-October, when optimistic estimates have it becoming bright enough to see with the unaided eye.  Each comet has a greenish coma of expelled gas and an ion tail pointing away from the Sun.    Growing Gallery: Comet SWAN25B

Image credit: Luc Perrot
(TWAN)
Comet Lemmon Brightens (2025-09-30)

Comet Lemmon is brightening and moving into morning northern skies. Besides Comet SWAN25B and Comet ATLAS, Comet C/2025 A6 (Lemmon) is now the third comet currently visible with binoculars and on long camera exposures.  Comet Lemmon was discovered early this year and is still headed into the inner Solar System. The comet will round the Sun on November 8, but first it will pass its nearest to the Earth -- at about half the Earth-Sun distance -- on October 21.  Although the brightnesses of comets are notoriously hard to predict, optimistic estimates have Comet Lemmon then becoming visible to the unaided eye. The comet should be best seen in predawn skies until mid-October, when it also becomes visible in evening skies.  The featured image showing the comet's split and rapidly changing ion tail was taken in Texas, USA late last week.    Growing Gallery: Comet Lemmon in 2025

Image credit: Victor Sabet & 
Julien De Winter
NGC 6960: The Witch's Broom Nebula (2025-10-01)

Ten thousand years ago, before the dawn of recorded human history, a new light would suddenly have appeared in the night sky and faded after a few weeks.  Today we know this light was from a supernova, or exploding star, and record the expanding debris cloud as the Veil Nebula, a supernova remnant.  This sharp telescopic view is centered on a western segment of the Veil Nebula cataloged as NGC 6960 but less formally known as the Witch's Broom Nebula.  Blasted out in the cataclysmic explosion, an interstellar shock wave plows through space sweeping up and exciting interstellar material. Imaged with narrow band filters, the glowing filaments are like long ripples in a sheet seen almost edge on, remarkably well separated into atomic hydrogen (red) and oxygen (blue-green) gas. The complete supernova remnant lies about 1400 light-years away towards the constellation Cygnus. This Witch's Broom actually spans about 35 light-years. The bright star in the frame is 52 Cygni, visible with the unaided eye from a dark location but unrelated to the ancient supernova remnant.

Image credit: Brian Meyers
Pluto at Night (2025-10-02)

The night side of Pluto spans this shadowy scene. In the stunning spacebased perspective, the Sun is 4.9 billion kilometers (almost 4.5 light-hours) behind the dim and distant world. It was captured by far flung New Horizons in July of 2015 when the spacecraft was at a range of some 21,000 kilometers from Pluto. That was about 19 minutes after its closest approach. A denizen of the Kuiper Belt in dramatic silhouette, the image also reveals Pluto's tenuous, surprisingly complex layers of hazy atmosphere. Near the top of the frame the crescent twilight landscape includes southern areas of nitrogen ice plains now formally known as Sputnik Planitia and rugged mountains of water-ice in the Norgay Montes.
Pandora's Cluster of Galaxies (2025-10-03)

This deep field mosaicked image presents a stunning view of galaxy cluster Abell 2744 recorded by the James Webb Space Telescope's NIRCam. Also dubbed Pandora's Cluster, Abell 2744 itself appears to be a ponderous merger of three different massive galaxy clusters. It lies some 3.5 billion light-years away, toward the constellation Sculptor. Dominated by dark matter, the mega-cluster warps and distorts the fabric of spacetime, gravitationally lensing even more distant objects. Redder than the Pandora cluster galaxies, many of the lensed sources are very distant galaxies in the early Universe, their lensed images stretched and distorted into arcs. Of course, distinctive diffraction spikes mark foreground Milky Way stars. At the Pandora Cluster's estimated distance, this cosmic box spans about 6 million light-years. But don't panic. You can explore the tantalizing region in a 2 minute video tour.
The Rotating Moon (2025-10-04)

No one on Earth sees the Moon rotate like this. That's because the Moon is tidally locked in synchronous rotation, showing only one side to denizens of our fair planet. Still, given modern digital technology, combined with many detailed images returned by the Lunar Reconnaissance Orbiter (LRO), a high resolution virtual Moon rotation movie can be composed. In fact, the featured time-lapse video starts with a view of the familiar lunar nearside and quickly finds the Mare Orientale, a large crater with a dark center that is difficult to see from the Earth, rotating into view just below the equator.  In a complete lunar rotation condensed into 24 seconds, the video clearly shows that the Earth-facing nearside of the Moon contains an abundance of dark lunar maria, while the lunar farside is dominated by bright lunar highlands. Of course, you can just join other moon-watchers under hopefully clear skies tonight. Check out the sunlit portion of the lunar nearside on International Observe the Moon Night.
A Long Storm System on Saturn (2025-10-05)

It was one of the largest and longest lived storms ever recorded in our Solar System.  First seen in late 2010, the featured cloud formation in the northern hemisphere of Saturn started larger than the Earth and soon spread completely around the planet.  The storm was tracked not only from Earth but from up close by the robotic Cassini spacecraft then orbiting Saturn. Pictured here in false colored infrared in February, orange colors indicate clouds deep in the atmosphere, while light colors highlight clouds higher up. The rings of Saturn are seen nearly edge-on as the thin blue horizontal line. The warped dark bands are the shadows of the rings cast onto the cloud tops by the Sun to the upper left. A source of radio noise from lightning, the intense storm was thought to relate to seasonal changes when spring emerges in the north of  Saturn. After raging for over six months, the iconic storm circled the entire planet and then tried to absorb its own tail -- which surprisingly caused it to fade away.
The Changing Ion Tail of Comet Lemmon (2025-10-06)

How does a comet tail change?  It depends on the comet.  The ion tail of Comet C/2025 A6 (Lemmon) has been changing markedly, as detailed in the featured image sequenced over six days between September 25 and October 4 (left to right) from Texas, USA.  On some days, the comet's ion tail was relatively more complex than other days. Reasons for tail changes include the rate of ejection of material from the comet's nucleus, the strength and complexity of the passing solar wind, and the rotation rate of the comet.  Sometimes, over the course of a week, apparent differences even result from a change of perspective from the Earth.  In general, a comet's ion tail will point away from the Sun, as gas expelled is pushed out by the Sun's wind.  Comet Lemmon is still inbound and brightening, passing nearest the Earth on October 21 and nearest the Sun on November 8.

Image credit: Victor Sabet & 
Julien De Winter
SN Encore: A Second Supernova Seen Several Times (2025-10-07)

Now a second supernova in this same galaxy is repeating. The cause is the gravitational lens effect of a massive foreground cluster of galaxies (MACS J0138) -- it creates multiple images of a perfectly aligned background galaxy (MRG-M0138). What's particularly interesting is that this background galaxy has young stars that keep blowing up. And images of each supernova explosion keep coming to us multiple times through different paths through the cluster. The original lensed supernova set, shown in the rollover, is called Requiem and was first seen by the Hubble Space Telescope in 2016.  This second lensed supernova set is called Encore and was first seen by the Webb Space Telescope in 2023.  More images from these supernovas are predicted to be on the way, and exactly when they arrive should help humanity to better understand the mass distribution of the galaxy cluster, the supernovas themselves, and possibly even the universe.
NGC 7380: The Wizard Nebula (2025-10-08)

What powers are being wielded in the Wizard Nebula?  Gravitation strong enough to form stars, and stellar winds and radiations powerful enough to create and dissolve towers of gas.  Located only 8,000 light years away, the Wizard nebula, featured here, surrounds a developing open star cluster NGC 7380.  Visually, the interplay of stars, gas, and dust has created a shape that appears to some like a fictional medieval sorcerer.  The active star forming region spans about 100 light years, making it appear larger than the angular extent of the Moon.  The Wizard Nebula can be located with a small telescope toward the constellation of the King of Aethiopia (Cepheus).  Although the nebula may last only a few million years, some of the stars being formed may outlive our Sun.

Image credit: Nevenka Blagovic Horvat & 
Miroslav Horvat
The Jenga Moon (2025-10-09)

That big, bright, beautiful Full Moon you watched rise on the night of October 6 was the Harvest Moon. Famed in festival, story, and song, Harvest Moon is just the traditional name of the full moon nearest the time of the northern hemisphere's autumnal equinox.  According to lore the name is a fitting one. Despite the diminishing daylight hours, as the growing season drew to a close in the north, farmers could harvest crops by the light of a full moon shining on from dusk to dawn. Later this year than usual, in 2025 October's Harvest Moon was also known to some as a supermoon, a term becoming a traditional name for a full moon near the time of lunar perigee. And this telephoto snapshot of the (almost) full moon rising above a conspicuous skyscraper in New York city, taken on October 5, is suggestive of yet another full moon moniker.

Image credit: Mike Carroll
50 Light-years to 51 Pegasi (2025-10-10)

It's only 50 light-years to 51 Pegasi. That star's position is indicated in this snapshot from August 2025, taken on a night with mostly brighter stars visible above the dome at Observatoire de Haute-Provence in France. Thirty years ago, in October of 1995, astronomers Michel Mayor and Didier Queloz announced a profound discovery made at the observatory. Using a precise spectrograph, they had detected a planet orbiting 51 Peg, the first known exoplanet orbiting a sun-like star. Mayor and Queloz had used the spectrograph to measure changes in the star's radial velocity, a regular wobble caused by the gravitational tug of the orbiting planet. Designated 51 Pegasi b, the planet was determined to have a mass at least half of Jupiter's mass and an orbital period of 4.2 days. That made the exoplanet much closer to its parent star than Mercury is to the Sun. Their discovery was quickly confirmed and Mayor and Queloz were ultimately awarded the Nobel Prize in physics in 2019. Now recognized as the prototype for the class of exoplanets fondly known as hot Jupiters, 51 Pegasi b was formally named Dimidium, Latin for half, in 2015. Since its discovery 30 years ago, over 6,000 exoplanets have been found.

Image credit: José Rodrigues
Manicouagan Impact Crater from Space (2025-10-11)

Orbiting 400 kilometers above Quebec, Canada, planet Earth, the International Space Station Expedition 59 crew captured this snapshot of the broad St. Lawrence River and curiously circular Lake Manicouagan on April 11, 2019. Right of center, the ring-shaped lake is a modern reservoir within the eroded remnant of an ancient 100 kilometer diameter impact crater. The ancient crater is very conspicuous from orbit, a visible reminder that Earth is vulnerable to rocks from space. Over 200 million years old, the Manicouagan crater was likely caused by the impact of a rocky body about 5 kilometers in diameter. Currently, there is no known asteroid with a significant probability of impacting Earth in the next century. Each month, NASA’s Planetary Defense Coordination Office releases an update featuring the most recent figures on near-Earth object close approaches, and other facts about comets and asteroids that could pose a potential impact hazard with Earth.
All the Water on Europa (2025-10-12)

How much of Jupiter's moon Europa is made of water? No one is sure, but probably a lot.  Based on the Galileo probe data acquired during its exploration of the Jovian system from 1995 to 2003, Europa possesses a deep, global ocean of liquid water beneath a layer of surface ice. The subsurface ocean plus ice layer could descend over 100 kilometers in average depth. Adopting a high-end estimate of 100 kilometers depth, if all the water on Europa were gathered into a ball,  it would have a radius of over 800 kilometers. To scale, this intriguing illustration compares that hypothetical ball of all the water on Europa to the size of Europa itself (left) - and similarly to all the water on planet Earth. With a volume possibly greater than Earth's oceans, the global subsurface ocean on Europa is a tantalizing destination to search for extraterrestrial life in our Solar System. NASA's robotic Europa Clipper was  launched last year to investigate.

Image credit: JPL/Caltech
Lemmon Tree (2025-10-13)

The tree is not in danger. That's because the comet pictured just above it, Comet C/2025 A6 (Lemmon), is far in the distance, well away from the Earth.  Comet Lemmon now continues to brighten as it arcs through the inner Solar System, even though it has passed its nearest to the Sun -- because it is now approaching the Earth. The comet will likely appear brightest when it is at its closest to the Earth next week, then closing to about half the Earth-Sun distance.  Comet Lemmon may then be visible to the unaided eye, but it is more likely to be imaged by a camera phone -- if you know where to look. Comet Lemmon, previously best visible in the morning, is now also visible in the evening sky for northern observers: look above the western horizon just after sunset. The featured image, centered on an unsuspecting European beech tree, was taken in Slovenia about ten days ago.

Image credit: Uroš Fink
An Unusual Globule in IC 1396 (2025-10-14)

Is there a monster in IC 1396?  Known to some as the Elephant's Trunk Nebula, parts of gas and dust clouds of this star formation region may appear to take on foreboding forms, some nearly human.  The only real monster here, however, is a bright young star too far from Earth to hurt us.  Energetic light from this star is eating away the dust of the dark cometary globule near the top of the featured image.  Jets and winds of particles emitted from this star are also pushing away ambient gas and dust.  Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a much larger region on the sky than shown here, with an apparent width of more than 10 full moons.

Image credit: Joachim Korb
Rocket Launch Plume over Tucson (2025-10-15)

Yes, but can your sunset do this? Looking west from Tucson, Arizona, USA one day last month, the sunset sky looked strange when it briefly lit up with the plume of a rocket launched from California a few minutes earlier. Appearing at times like a giant space fish, the impressive rocket launch from Vandenberg Air Force Base near Lompoc, California, was so noticeable because it was backlit by the setting Sun. The Falcon 9 rocket successfully delivered to low Earth orbit 28 Starlink communications satellites.  The plume from the first stage is seen on the right, while the soaring upper stage rocket is seen at the apex of the plume on the far left. The picturesque foreground includes the arms of saguaro cacti, city lights of Tucson, and the Tucson Mountains.

Image credit: Wayne Showalter
Young Suns of NGC 7129 (2025-10-16)

Young suns still lie within dusty NGC 7129, some 3,000 light-years away toward the royal constellation Cepheus. While these stars are at a relatively tender age, only a few million years old, it is likely that our own Sun formed in a similar stellar nursery around five billion years ago. Notable in the sharp image are the lovely bluish dust clouds that reflect the youthful starlight. But the compact, deep red crescent shapes are also markers of energetic, young stellar objects. Known as Herbig-Haro objects, their shape and color are characteristic of glowing hydrogen gas shocked by jets streaming away from newborn stars. Paler, extended filaments of reddish emission mingling with the bluish clouds are caused by dust grains effectively converting the invisible ultraviolet starlight to visible red light through photoluminesence. Ultimately the natal gas and dust in the region will be dispersed, the stars drifting apart as the loose cluster orbits the center of the Galaxy. At the estimated distance of NGC 7129, this telescopic field of view spans nearly 40 light-years.

Image credit: Timothy Martin
Ida and Dactyl: Asteroid and Moon (2025-10-17)

This asteroid has a moon.  The robot spacecraft Galileo enroute to explore the Jovian system in 1993, encountered and photographed two asteroids during its long interplanetary voyage.  The second minor planet it photographed, 243 Ida, was discovered to have a moon. The tiny moon, named Dactyl, is only about 1.6 kilometers across and seen as a small dot to the right in the image.  In contrast, Ida is much larger, measuring about 60 kilometers long and 25 km wide.  In fact, Dactyl is the first moon of an asteroid ever discovered. But now many asteroids are known to have moons. Minor planet names Ida and Dactyl were taken from Greek mythology.
3D Bennu (2025-10-18)

Put on your red/blue glasses and float next to asteroid 101955 Bennu. Shaped like a spinning toy top with boulders littering its rough surface, the tiny Solar System world is about one Empire State Building (less than 500 meters) across. Frames used to construct this 3D anaglyph were taken by PolyCam on the OSIRIS_REx spacecraft on December 3, 2018 from a distance of about 80 kilometers. With a sample from the asteroid's rocky surface on board, OSIRIS_REx departed Bennu's vicinity in May of 2021. The robotic spacecraft successfully returned the sample to its home world in September of 2023.