NASA Astronomy Picture of the Day:

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.

Photo by NASA / GSFC / Arizona State Univ. / Lunar Reconnaissance Orbiter

NASA Astronomy Picture of the Day:

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.

Photo by HiRISE, MRO, LPL (U. Arizona), NASA

NASA Astronomy Picture of the Day:

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!

Photo by Tom Williams

NASA Astronomy Picture of the Day:

"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).

Photo by 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).

NASA Astronomy Picture of the Day:

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.

Photo by ESA, CAS, SMILE, UVI

NASA Astronomy Picture of the Day:

A deep image of the Sombrero galaxy reveals surprises. M104 is named the Sombrero galaxy because, on shorter exposures, it looks like a hat. A key defining feature of this huge galaxy is a dark brim of dust that circles the disk galaxy's center. A much longer exposure, however, brings up a hairy past where a bright, hazy halo is revealed that extends well past the central disk and contains many unresolved stars. Surprisingly, in this stellar haze, structures can be seen that include a diagonal ring. These structures and tidal streams provide fresh evidence that M104 had a violent past and is surely the result of collisions and mergers of smaller galaxies. Light takes about 30 million years to reach us from the Sombrero galaxy, which fully spans about 150 thousand light years across. The featured image was taken over seven days in mid-2026 from Namibia.

Photo by Engelbert Vollmer

NASA Astronomy Picture of the Day:

Yes, but can your rainbow do this? After the remnants of Hurricane Florence passed over the Jersey Shore, New Jersey, USA in 2018, the Sun came out in one direction but something quite unusual appeared in the opposite direction: a hall of rainbows. Over the course of the next half hour, to the delight of the photographer and his daughter, vibrant supernumerary rainbows faded in and out, with at least five captured in this featured single shot. Supernumerary rainbows only form when falling water droplets are all nearly the same size and typically less than a millimeter across. Then, sunlight will not only reflect from inside the raindrops, but interfere, a wave phenomenon similar to ripples on a pond when a stone is thrown in. In fact, supernumerary rainbows can only be explained with waves, and their noted existence in the early 1800s was considered early evidence of light's wave nature.

Photo by John Entwistle

NASA Astronomy Picture of the Day:

On sol 1943 of its journey of exploration across the surface of Mars, the Curiosity Rover recorded this selfie at the south rim of Vera Rubin Ridge. Of course a sol is a Martian solar day, about 40 minutes longer than an Earth day. Curiosity's sol 1943 corresponds to Earth date January 23, 2018. Also composed as an interactive 360 degree VR, the mosaicked panorama combines 61 exposures taken by the small car-sized rover's Mars Hand Lens Imager (MAHLI). Frames containing the imager's arm have been edited out while the extended background used was taken by the rover's Mastcam on sol 1903. At the top of the rover's mast, sitting above the Mastcam, the laser-firing ChemCam housing blocks out the distant, 5 kilometer high peak of Mount Sharp. On Earth date August 26, 2026, Curiosity marked an total elevation gain of 1 kilometer in its trek from the floor of Gale Crater up the slope of Mount Sharp.

Photo by NASA, JPL-Caltech, MSSS - Panorama: Andrew Bodrov

NASA Astronomy Picture of the Day:

What does it take to image hundreds of nebulas? Today’s image contains the entire Sharpless Catalog of H II Regions, totaling 313 objects. Zoom in and explore! You may spot fan favorites like the Eagle (Sh2-49), Heart (Sh2-190), and Orion (Sh2-281) Nebulas. Despite its name, this catalog contains more than the glow of ionized hydrogen that makes up H II regions. There are planetary nebulas (the Medusa Nebula, Sh2-274) and supernova remnants (the Spaghetti Nebula, Sh2-240) as well. Astrophotographer Bing Xin traversed the dark skies of Eastern China and Inner Mongolia to catch them all. Narrowband filters that primarily capture light from ionized hydrogen and oxygen as well as red-green-blue filters were used. Each object took 2 to 6 hours to capture, with the entire catalog taking around 800 hours to complete! Which object is your favorite?

Photo by Bing Xin

NASA Astronomy Picture of the Day:

Have you ever seen the full moon rise? This colorful image was photographed last weekend in Sicily, just outside the town of Nicosia, in Italy. It is a composite photograph that shows the Moon rising as the sky turns darker. Lower clouds are reflecting the colors of antitwilight, while ash and gas from Mount Etna are seen higher in the background. The pink band lower in the sky is called the Belt of Venus. During a full moon, the Moon and the Sun are in opposition in the sky: the moon rises as the sun sets. The lunar phase cycle lasts approximately 29.5 days (but the Moon takes approximately 27 days to orbit the Earth). In some cultures of the Northern Hemisphere, the September full moon is called the Harvest Moon. Does your culture have a special name for it? (A full moon by any other name would shine as bright.)

Photo by Dario Giannobile

NASA Astronomy Picture of the Day:

Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries. Some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy, the island universe is an enormous 200,000 light-years across. Also known as NGC 772, it sports a prominent, outer spiral arm in this detailed cosmic portrait. Tracking along sweeping dust lanes and lined with young blue star clusters, Arp 78's overdeveloped spiral arm is pumped-up by galactic-scale gravitational tides. Interactions with its brightest companion galaxy, the more compact NGC 770 seen directly below the larger spiral, are likely responsible. Embedded in faint star streams revealed in the deep telescopic exposure, NGC 770's fuzzy, elliptical appearance contrasts nicely with spiky foreground Milky Way stars.

Photo by Robert Eder

NASA Astronomy Picture of the Day:

What causes the swirl in the Shrimp Nebula? Its high speed is likely. What is sure is that Sh2-188 is one of the larger planetary nebulas on the night sky, by angular size, spanning about half the diameter of the Moon. Moreover, the white-dwarf core -- leftover from the Sun-like star that shed its outer atmosphere -- is moving unusually fast through interstellar space, creating a bow shock most visible on the upper left that is similar to a boat plowing through water. Although faint, the Shrimp Nebula glows also by compressing and brightening gas on its leading edge. The featured image was taken in the light of hydrogen, sulfur, and oxygen by a backyard telescope in Krakow, Poland and then digitally adjusted to approximate the nebula's true colors.

Photo by Pawel Piechnik