Dark Matter in a Simulated Universe
Image Credit: Tom Abel & Ralf Kaehler (KIPAC , SLAC), AMNH

Explanation: Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters so fast, why gravitational lenses so strongly deflect light, and how visible matter is distributed. The featured image from the American Museum of Natural History's Hayden Planetarium Space Show, Dark Universe, highlights one example of how pervasive dark matter might haunt our universe. In this frame from a detailed computer simulation, complex filaments of dark matter, shown in black, are strewn about the universe like spider webs, while the relatively rare clumps of familiar baryonic matter are colored orange. These simulations are good statistical matches to astronomical observations. In what is perhaps a scarier turn of events, dark matter -- although quite strange and in an unknown form -- is no longer thought to be the strangest source of gravity in the universe. That honor now falls to dark energy, a more uniform source of repulsive gravity that seems to now dominate the expansion of the entire universe.

https://science.nasa.gov/image-article/apod-2026-october-25-dark-matter-in-a-simulated-universe/ #apod

Rosetta's Selfie
Image Credit: ESA/Rosetta/Philae/CIVA

Explanation: This Rosetta spacecraft selfie was snapped on October 7th, 2014. At the time the comet-chasing spacecraft was about 472 million kilometers from planet Earth, but only 16 kilometers from the surface of comet 67P/Churyumov-Gerasimenko. Looming beyond the spacecraft near the top of the frame, dust and gas stream away from the comet's curious double-lobed nucleus. Bright sunlight glints off one of Rosetta's 14 meter long solar arrays. In fact, two exposures, one short and one long, were combined to record the dramatic high contrast scene using the CIVA camera system on Rosetta's still-attached Philae lander. Its chosen primary landing site was on the visible hemisphere of the smaller lobe of the nucleus. This was the last image from Philae's camera before the lander separated from Rosetta on November 12. Shortly after separation Philae took another image looking back toward the orbiter and began its descent to the nucleus of the comet.

https://science.nasa.gov/image-article/apod-2026-october-24-rosettas-selfie/ #apod

Andromeda in Southern Spring
Image Credit: Lucy Yunxi Hu

Explanation: Looking toward the north from Mullion, New South Wales, Australia, the Andromeda Galaxy never gets more than a few degrees above the horizon. During the southern hemisphere spring, Andromeda is highest in the sky around midnight though. And in this telephoto scene from October 10/11, multiple exposures were used to reveal the spiral galaxy in tantalizing detail as it climbed above rolling Australian hills. Also known as M31, the Andromeda Galaxy is one of the brightest objects in the Messier catalog, but is only visible to the unaided eye as a small, faint, fuzzy patch. Digitally tracked and stacked frames were combined with a foreground shot in the deep astro-image composite to reveal the galaxy's greater extent in planet Earth's night. In the springtime night skyscape,the closest large spiral galaxy spans nearly 6 full moons.

https://science.nasa.gov/image-article/apod-2026-october-23-andromeda-in-southern-spring/ #apod

The First Green Star, WD J1330+6435
Image Credit: Mark A. Garlick/University of Warwick

Explanation: Star light, star bright: is there a green star out tonight? Other than the Sun, all stars are so far from Earth that they appear as points in the sky. They are mostly white, but sometimes noticeably red or blue. This color typically relates to the temperature: blue stars are hotter than red stars. What about other colors? The featured image is an illustration showing WD J1330+6435, a white dwarf star, surrounded by an accretion disk with gas and rocks orbiting the star. White dwarfs are small, faint stars that are left over when a star like the Sun exhausts its nuclear fuel. Astronomers recently found that some white dwarf stars, despite their name, would appear yellow, green, cyan, pink, or purple. In these cases, trace elements that were accreted to these stars interact with the stellar atmosphere and shift its normally white color. But, alas! I wish I may, I wish I might, but they are too faint to see tonight...

https://science.nasa.gov/image-article/apod-2026-october-22-the-first-green-star-wd-j13306435/ #apod

New Ghosts Revealed in Cassiopeia
Image Credit: Louis Leroux-Géré, Thibault Rouillée, Vincent Martin, Cédric de Decker (Starfront Observatories)

Explanation: Jinkies, look at all those ghosts! It took 100 hours of observation and a special oxygen filter for today’s image to capture three faint nebulas hidden in the Cassiopeia constellation. IC 59 and IC 63, the original Ghosts of Cassiopeia, haunt the region near multi-star system γ Cassiopeia. Energetic light from γ Cassiopeia causes the hydrogen gas in IC 59 and 63 to glow red. Their dust reflects and scatters some blue-ish white starlight. Newly discovered Objects 1, 2, and 3 appear as blue phantoms, revealing the presence of ionized oxygen. But ionized by what? Like at the bow of a speeding boat, γ Cassiopeia may be piling up material as the system moves through interstellar gas and dust. It follows that Object 3 may be the compressed and heated oxygen of that bow shock. Object 1 could be a planetary nebula if a central white dwarf is identified. The origins of these astronomical apparitions remain a mystery to be solved.

https://science.nasa.gov/image-article/apod-2026-october-21-new-ghosts-revealed-in-cassiopeia/ #apod

An Anticrepuscular Rainbow Fan
Image Credit: Aurelia Degli Esposti

Explanation: This is an unusual rainbow. For one thing, the rainbow is not complete, appearing only in a sunlit fan -- but that by itself is not very unusual. What is most unusual is the fake location of the Sun. The Sun appears to be toward the front, just below those hills -- but it is not. That is not how rainbows work. Rainbows involve a backward reflection from falling rain, so that the Sun must really be behind you. In this case, gaps between clouds near the setting Sun allowed rays to cross the entire sky and appear to converge in front, an unusual phenomenon called anticrepuscular rays. The photo was taken with a phone last week at sunset in Presenzano, Italy. The seemingly reverse rainbow was noticed when hanging up laundry.

https://science.nasa.gov/image-article/apod-2026-october-20-an-anticrepuscular-rainbow-fan/ #apod

Treble Clef: Unusual X-ray Hot Radio Source
Image Credit & Copyright: X-ray: NASA/CXC/INAF-IRA/A. Botteon et al.; Infrared: UKIDSS-GPS; Radio: ASTRONLOFAR; Image processing: NASA/CXC/SAO/N. Wolk

Explanation: Explanation : What is Treble Clef? This unusual radio structure extends over 2 million light-years and resembles a common musical symbol -- but has its visible light hidden by our own Milky Way Galaxy. Examined in 2004, the nature of VLSS J0318.9+5755, dubbed Treble Clef, remained unknown. Recent observations by the Chandra X-ray Observatory and eROSITA, however, have led to the hypothesis that the Treble Clef central cloud of charged particles was originally expelled by a supermassive black hole at the center of a galaxy. After the radio emission from those particles faded, they may have been reinvigorated by a shock wave from the collision of two clusters of galaxies. The featured composite image shows radio emission in red, while recently discovered X-rays are shown in blue. Unusual objects like Treble Clef give humanity unexpected clues about how whole clusters of galaxies interact as well as the general evolution of our universe.

https://science.nasa.gov/image-article/apod-2026-october-19-treble-clef-unusual-x-ray-hot-radio-source/ #apod

Sonified: Eagle Nebula Pillars
Image Credit: NASA, ESA, & The Hubble Heritage Project (STScI/AURA);
Sonification: NASA, CXC, SAO, K. Arcand, M. Russo & A. Santaguida

Explanation: Yes, but have you ever experienced the Eagle Nebula with your ears? The famous nebula M16 is best known for the feast it gives your eyes, highlighting bright young stars forming deep inside dark towering structures. These light-years long columns of cold gas and dust are some 6,500 light-years distant toward the constellation of the Serpent (Serpens). Sculpted and eroded by the energetic ultraviolet light and powerful winds from M16's cluster of massive stars, the cosmic pillars themselves are destined for destruction. But the turbulent environment of star formation within M16, whose spectacular details are captured in this combined Hubble (visible) and Chandra (X-ray) image, is likely similar to the environment that formed our own Sun. In the featured video, listen for stars and dust sounding off as the line of sonification moves left to right, with vertical position determining pitch.

https://science.nasa.gov/image-article/apod-2026-october-18-sonified-eagle-nebula-pillars/ #apod

3D 67P
Image Credit: ESA , Rosetta , MPS , OSIRIS - Stereo Anaglyph: Philippe Lamy and The Team

Explanation: Put on your red/blue glasses and float next to the jagged and double-lobed nucleus of Churyumov-Gerasimenko, also known as Comet 67P . The stereo anaglyph was created by combining two images from the Rosetta spacecraft's narrow angle OSIRIS camera taken on July 25, 2015 from a distance of 184 kilometers. Numerous jets are emanating from the small solar system world's active surface near its closest approach to the Sun. The larger lobe is around 4 kilometers in diameter, joined to a smaller, 2.5 kilometer diameter lobe by a narrow neck. Rosetta's mission to the comet ended in September 2016 when the spacecraft was commanded to a controlled impact with the comet's surface . Keep those 3D glasses on though. You can check out a catalog of nearly 1400 stereo anaglyphs created from Rosetta image data on this website.

https://science.nasa.gov/image-article/apod-2026-october-17-3d-67p/ #apod

Chasing the International Space Station
Credit: Eric Holland

Explanation: Blasting into the predawn sky on Tuesday, October 13, a Falcon 9 rocket and Dragon spacecraft are headed for low Earth orbit in this stunning timelapse video captured from Indian Harbour Beach, Florida. Starting with a launch from Space Launch Complex 40 at Cape Canaveral Space Force Station, Falcon and Dragon are chasing the International Space Station on NASA's 35th Commercial Resupply Services mission. On cue, the space station itself enters the frame from the top. Almost 8 seconds into the 30 second timelapse. the bright streak of the ISS appears heading "down" toward the horizon. The first and second stages of the Falcon 9 are separating as the spectacular exhaust plume jellyfish grows, already catching the light of the rising Sun. The visible sequence of first stage boost back, re-entry, and landing burns begins around 20 seconds into the video. With the second stage following the ISS toward the distant horizon, the jellyfish plume continues to drift in the predawn sky, even after the successful first stage landing at planet Earth's Landing Zone 40.

https://science.nasa.gov/image-article/apod-2026-october-16-chasing-the-international-space-station/ #apod

The Milky Way over Manhattan
Image Credit: Jason Kurth, Ty Buckley

Explanation: The city lights outshine the stars in the City That Never Sleeps. Who would have thought that the Milky Way could be visible in this sky? This image was taken with a filter that blocks most visible light, capturing instead only light in the near-infrared region of the electromagnetic spectrum (with lower energy than visible light). The astrophotographer's clever setup blocks most of the light pollution from the city: old incandescent light bulbs and some neon lights are still bright in the near-infrared, but fluorescent and LED light bulbs are not. Of course, stars are also bright in the near-infrared! This image is a reminder that we all live under the same sky, and astronomy allows all of us to learn more about humanity's place in the Cosmos.

https://science.nasa.gov/image-article/apod-2026-october-15-the-milky-way-over-manhattan/ #apod

Mars and the Beehive Under an Aurora
Image Credit: Petr Horálek (Institute of Physics in Opava), Josef Kujal, Vojan Höfer

Explanation: What a cosmic coincidence! In today’s image, Mars joins the Beehive cluster (M44 or Praesepe) below an auroral curtain and above a horizon of happy little trees near Lansjärv, Sweden. An eruption off the Sun reached Earth on October 10th, 2026 causing strong disturbances in Earth’s magnetic field. Energetic particles from the eruption collide with and energize the molecules in Earth’s atmosphere, which release that extra energy as the colorful aurora captured here. Auroras, or guovssahasat in North Sámi, is traditionally viewed with respect by the Sámi people indigenous to Sweden and other Arctic regions. Coincidentally, Mars appeared closest to the center of the Beehive cluster in the sky at the time. Although bees have been to space, the Beehive cluster is actually a swarm of young stars. Their rotation periods have helped humanity learn about how stars spin slower over time as they lose mass through their stellar winds.

https://science.nasa.gov/image-article/apod-2026-october-14-mars-and-the-beehive-under-an-aurora/ #apod

Desert Stairway to Heaven
Image Credit: Julien Looten

Explanation: This stairway in Chile brings you only a little bit closer to heaven. But ooh, the sky above it makes you wonder. For example, you may wonder about the dark lane of our own Milky Way galaxy rising behind the expansive Atacama Desert in Chile, the band of zodiacal light on the upper left, the green and red airglow just above the horizon, the star Spica in the zodiacal light stripe, and, at the very top on the right, the Small Magellanic Cloud galaxy. The Desert Staircase sculpture is in the foreground, and this image was timed to catch the picturesque peering perch just in front of the near-vertical Milky Way band. Upon close inspection of the horizon you can find, left to right, some Andes Mountains, the Licancabur volcano, and the town lights of San Pedro de Atacama. The featured wide-angle composite was captured in July 2025.

https://science.nasa.gov/image-article/apod-2026-october-13-desert-stairway-to-heaven/ #apod

Jupiter and the Moons
Image Credit: Chirag Upreti

Explanation: How many moons can you see? The best answer is five: four orbiting Jupiter and Luna orbiting Earth. This multi-moon picture was possible because Earth's Moon moved directly in front of Jupiter last week. The featured image is a series of exposures near alignment taken from Westchester, New York, USA. The sunlit crescent of Earth's Moon, on the lower left, is overexposed, while the Moon's night side, on the upper right, is faintly illuminated by Earthshine. Lined up nearly vertically above our Moon, listed from bottom to top, are Jupiter's bright Galilean satellites: Ganymede, Io, Callisto, and Europa. Callisto, Ganymede, and Io are larger than Earth's Moon, while Europa is only slightly smaller. NASA's robotic spacecraft Juno is currently orbiting Jupiter and has made close passes near three of these moons.

https://science.nasa.gov/image-article/apod-2026-october-12-jupiter-and-the-moons/ #apod

Ice Fishing for Cosmic Neutrinos
Image Credit & Copyright: NSF, B. Gudbjartsson, IceCube Collaboration

Explanation: Scientists are melting holes in the bottom of the world. In fact, almost 100 holes melted near the South Pole are now being used as an astronomical observatory. Astronomers with the IceCube Neutrino Observatory lowered a long string knotted with basketball-sized light detectors into each vertical lake. The water in each hole soon refreezes. The detectors attached to the strings are sensitive to blue light emitted in the surrounding clear ice. Such light results from fast-moving secondary particles liberated when high-energy neutrinos emitted by powerful processes out in the universe collide with ice molecules. IceCube has now detected many illuminating neutrinos. Pictured in 2010, one of the last of IceCube's detector strings is lowered into the freezing abyss, making IceCube the largest neutrino detector ever created. In recognition of unprecedented discoveries, it was announced earlier this week that a founding leader of the IceCube Collaboration will be awarded the Nobel Prize in Physics.

https://science.nasa.gov/image-article/apod-2026-october-11-ice-fishing-for-cosmic-neutrinos/ #apod

Lunar Farside
Image Credit: NASA / GSFC / Arizona State Univ. / Lunar Reconnaissance Orbiter

Explanation: Tidally locked in synchronous rotation, the Moon always presents its familiar nearside to denizens of planet Earth. From lunar orbit, the Moon's farside can become familiar, though. In fact this sharp picture, a mosaic from the Lunar Reconnaissance Orbiter's wide angle camera, is centered on the lunar farside. Part of a global mosaic of over 15,000 images acquired between November 2009 and February 2011, the highest resolution version shows features at a scale of 100 meters per pixel. Surprisingly, the rough and battered surface of the farside looks very different from the nearside covered with smooth dark lunar maria. A likely explanation is that the farside crust is thicker, making it harder for molten material from the interior to flow to the surface and form dark, smooth maria.

https://science.nasa.gov/image-article/apod-2026-october-10-lunar-farside/ #apod

Stickney Crater
Image Credit: HiRISE, MRO, LPL (U. Arizona), NASA

Explanation: 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 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 in March of 2008. Even though the surface gravity of asteroid-like Phobos is less than 1/1000th Earth's gravity, streaks suggest loose material 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 tidal stresses experienced by close-orbiting Phobos or the crater-forming impact itself.

https://science.nasa.gov/image-article/apod-2026-october-9-stickney-crater/ #apod

The Saturn System Smörgåsbord
Image Credit: Tom Williams

Explanation: How was the Saturn system imaged so clearly? Astrophotographer Tom Williams captured such exquisite details due to one night of exceptional atmospheric conditions above the United Kingdom. This means more than a cloudless sky. Pockets of air at different temperatures and densities move around and bend light as it travels through Earth’s atmosphere, distorting astronomy images. This is called “seeing”. Less atmospheric turbulence means clearer images. The astrophotographer reduced the impact of seeing with the lucky imaging technique: thousands of short-exposure images are taken very quickly with a high-speed camera and the clearest images are added up. Which object in this smörgåsbord interests you? Perhaps Titan or the icy stripes of Enceladus? Maybe the gaps and spokes in Saturn’s rings? Saturn's opposition, when Earth passes in between the planet and the Sun, occurred on October 4th. Due to the planet's proximity and full illumination from the Sun, now is a great time of year to observe it!

https://science.nasa.gov/image-article/apod-2026-october-8-the-saturn-system-smorgasbord/ #apod

Supernova Remnant Pa 30
Image Credit: International Gemini Observatory/NOIRLab/NSF/AURA. Acknowledgment: PI: T. Cunningham (Center for Astrophysics - Harvard & Smithsonian). Image Processing: J. Miller & M. Rodriguez (International Gemini Observatory/NSF NOIRLab), T.A. Rector (University of Alaska Anchorage/NSF NOIRLab), D. de Martin & M. Zamani (NSF NOIRLab).

Explanation: "Happy New Year!" No, wait, this is not a fireworks display. This image shows Nebula Pa 30, observed with the Gemini North Telescope in Hawai'i. It is likely the remnant of an old supernova explosion: separate historical records by Chinese, Japanese and Arabic astronomers tell of a "guest star" that appeared in the sky for 185 days in the year 1181. It is believed that this bright new point of light came from the supernova that caused the fireworks in Pa 30. Astronomers don't know exactly what happened in this unusual explosion, classified as a Type Iax supernova, but it is thought to be caused by the merger of two white dwarfs. The mysterious central star in the image is extremely hot and produces a strong wind, possibly forming the radial filaments. Look closely at them: those pearl-like knots stringing the filaments are 4 light-days in diameter. Understanding how a supernova created this amazing nebula continues an 845-year old mystery (and counting).

https://science.nasa.gov/image-article/apod-2026-october-7-supernova-remnant-pa-30/ #apod

A Complete Auroral Oval from SMILE
Image Credit: ESA, CAS, SMILE, UVI

Explanation: Have you ever seen a complete auroral oval? You can't see one from the ground because it makes too large a circle around one of Earth's magnetic poles. But spacecraft high above the Earth can see them. The featured video from ESA and CAS's robotic SMILE spacecraft shows not only a full auroral oval, but using ultraviolet light, one that occurred during the day. The time-lapse covers about an hour in late July and shows visually how variable and turbulent auroras really are. The points of light on the sides are distant stars that appear to move only because SMILE's camera view shifts as the spacecraft orbits the Earth. A goal of SMILE is to better understand how the Sun's wind interacts with the Earth's magnetosphere -- and so better understand how to protect astronauts, spacecraft, and ground-based electrical grids from solar storms.

https://science.nasa.gov/image-article/apod-2026-october-6-a-complete-auroral-oval-from-smile/ #apod