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NASA Astronomy Picture of the Day:

Now outbound after its perihelion or closest approach to the Sun on October 29, Comet 3I/ATLAS is only the third known interstellar object to pass through our fair Solar System. Its greenish coma and faint tails are seen against a background of stars in the constellation Virgo in this view from planet Earth, recorded with a small telescope on November 14. But this interstellar interloper is the subject of an on-going, unprecedented Solar System-wide observing campaign involving spacecraft and space telescopes from Earth orbit to the surface of Mars and beyond. And while the comet from another star-system has recently grown brighter, you'll still need a telescope if you want to see 3I/ATLAS from planet Earth. It's now above the horizon in November morning skies and will make its closest approach to Earth, a comfortable 270 million kilometers distant, around December 19.

Photo by Rolando Ligustri

NASA Astronomy Picture of the Day:

Alnitak, Alnilam, and Mintaka are the bright bluish stars from east to west (upper right to lower left) along the diagonal in this cosmic vista. Otherwise known as the Belt of Orion, these three blue supergiant stars are hotter and much more massive than the Sun. They lie from 700 to 2,000 light-years away, born of Orion's well-studied interstellar clouds. In fact, clouds of gas and dust adrift in this region have some surprisingly familiar shapes, including the dark Horsehead Nebula and Flame Nebula near Alnitak at the upper right. The famous Orion Nebula itself is off the right edge of this colorful starfield. The telescopic frame spans almost 4 degrees on the sky.

Photo by Aygen Erkaslan

NASA Astronomy Picture of the Day:

Sometimes the dark dust of interstellar space has an angular elegance. Such is the case toward the far-south constellation of Chamaeleon. Normally too faint to see, dark dust is best known for blocking visible light from stars and galaxies behind it. In this 11.4-hour exposure, however, the dust is seen mostly in light of its own, with its strong red and near-infrared colors creating a brown hue. Contrastingly blue, a bright star Beta Chamaeleontis is visible on the upper right of the V, with the dust that surrounds it preferentially reflecting blue light from its primarily blue-white color. All of the pictured stars and dust occur in our own Milky Way Galaxy with one notable exception: a white spot just below Beta Chamaeleontis is the galaxy IC 3104, which lies far in the distance. Interstellar dust is mostly created in the cool atmospheres of giant stars and dispersed into space by stellar light, stellar winds, and stellar explosions such as supernovas.

Photo by Xinran Li & Houbo Zhao

NASA Astronomy Picture of the Day:

What has happened to Comet Lemmon's tail? The answer is blowing in the wind — the wind from the Sun in this case. This continuous outflow of charged particles from the Sun has been quite variable of late, as the Sun emits bursts of energy, CMEs, that push out and deflect charged particles emitted by the comet itself. The result is a blue hued ion tail for Comet C/2025 A6 (Lemmon) that is not only impressively intricate but takes some unusual turns. This long-duration composite image taken from Alfacar, Spain last month captured this inner Solar System ionic tumult. Comet Lemmon is now fading as it heads out away from the Earth and Sun and back into the outer Solar System.

NASA Astronomy Picture of the Day:

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.

NASA Astronomy Picture of the Day:

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.

Photo by Robert Barsa

NASA Astronomy Picture of the Day:

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.

Photo by Wayne Showalter

NASA Astronomy Picture of the Day:

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.

Photo by Brian Meyers

NASA Astronomy Picture of the Day:

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

Photo by Victor Sabet & Julien De Winter

NASA Astronomy Picture of the Day:

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

Photo by Luc Perrot (TWAN)

NASA Astronomy Picture of the Day:

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.

NASA Astronomy Picture of the Day:

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 north 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.

Photo by Pascal Fouquet