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Explanation: What is going on with this galaxy? NGC 2685 is a confirmed polar ring galaxy - a rare type of galaxy with stars, gas and dust orbiting in rings perpendicular to the plane of a flat galactic disk. The bizarre configuration could be caused by the chance capture of material from another galaxy by a disk galaxy, with the captured debris strung out in a rotating ring. Still, observed properties of NGC 2685 suggest that the rotating helix structure is remarkably old and stable. In this sharp view of the peculiar system also known as Arp 336 or the...

Explanation: Why isn't this ant a big sphere? Planetary nebula Mz3 is being cast off by a star similar to our Sun that is, surely, round. Why then would the gas that is streaming away create an ant-shaped nebula that is distinctly not round? Clues might include the high 1000-kilometer per second speed of the expelled gas, the light-year long length of the structure, and the magnetism of the star featured here at the nebula's center. One possible answer is that Mz3 is hiding a second, dimmer star that orbits close in to the bright star. A competing hypothesis holds...

Explanation: As the Sun set, a bright Full Moon rose on July 10. Its golden light illuminates clouds drifting through southern hemisphere skies in this well-composed telephoto image from Conceição do Coité, Bahia, Brazil. The brightest lunar phase is captured here with both a short and long exposure. The two exposures were combined to reveal details of the lunar surface in bright moonlight and a subtle iridescence along the dramatically backlit cloudscape. Of course, July's Full Moon is a winter moon in the southern hemisphere. But in the north it's known to some as the Thunder Moon, likely a nod...

Explanation: Transfusing sunlight as the sky grew darker, this exceptional display of noctilucent clouds was captured on July 10, reflected in the calm waters of Vallentuna Lake near Stockholm, Sweden. From the edge of space, about 80 kilometers above Earth's surface, the icy clouds themselves still reflect sunlight, even though the Sun is below the horizon as seen from the ground. Usually spotted at high latitudes in summer months, the night shining clouds have made a strong showing so far during the short northern summer nights. Also known as polar mesopheric clouds they are understood to form as water vapor...

Explanation: Stars are forming in Lynds Dark Nebula (LDN) 1251. About 1,000 light-years away and drifting above the plane of our Milky Way galaxy, LDN 1251 is also less appetizingly known as "The Rotten Fish Nebula." The dusty molecular cloud is part of a complex of dark nebulae mapped toward the Cepheus flare region. Across the spectrum, astronomical explorations of the obscuring interstellar clouds reveal energetic shocks and outflows associated with newborn stars, including the telltale reddish glow from scattered Herbig-Haro objects hiding in the image. Distant background galaxies also lurk in the scene, almost buried behind the dusty expanse....

Explanation: The beautiful Trifid Nebula is a cosmic study in contrasts. Also known as M20, it lies about 5,000 light-years away toward the nebula rich constellation Sagittarius. A star forming region in the plane of our galaxy, the Trifid does illustrate three different types of astronomical nebulae; red emission nebulae dominated by light from hydrogen atoms, blue reflection nebulae produced by dust reflecting starlight, and dark nebulae where dense dust clouds appear in silhouette. But, the red emission region roughly separated into three parts by obscuring dust lanes is what lends the Trifid its popular name. Pillars and jets sculpted...

Explanation: If you have looked at the sky and seen a group of stars about the size of the full Moon, that's the Pleiades (M45). Perhaps the most famous star cluster in the sky, its brightest stars can be seen even from the light-polluted cities. But your unaided eye can also see its nebulosity -- the gas and dust surrounding it -- under dark skies. However, telescopes can catch even more. The bright blue stars of the Pleiades, also known as the Seven Sisters, light up their surrounding dust, causing it to appear a diffuse blue that can only be...

Explanation: It came from outer space. An object from outside our Solar System is now passing through at high speed. Classified as a comet because of its gaseous coma, 3I/ATLAS is only the third identified macroscopic object as being so alien. The comet's trajectory is shown in white on the featured map, where the orbits of Jupiter, Mars, and Earth are shown in gold, red, and blue. Currently Comet 3I/ATLAS is about the distance of Jupiter from the Sun -- but closing, with its closest approach to our Sun expected to be within the orbit of Mars in late October....

Explanation: Why is there a spiral around the North Pole of Mars? Each winter this pole develops a new outer layer about one meter thick composed of carbon dioxide frozen out of the thin Martian atmosphere. This fresh layer is deposited on a water-ice layer that exists year round. Strong winds blow down from above the cap's center and swirl due to the spin of the red planet -- contributing to Planum Boreum's spiral structure. The featured image is a perspective mosaic generated in 2017 from numerous images taken by ESA's Mars Express and elevations extracted from the laser altimeter...

Explanation: Difficult to capture, this mysterious, squid-shaped interstellar cloud spans nearly three full moons in planet Earth's sky. Discovered in 2011 by French astro-imager Nicolas Outters, the Squid Nebula's bipolar shape is distinguished here by the telltale blue emission from doubly ionized oxygen atoms. Though apparently surrounded by the reddish hydrogen emission region Sh2-129, the true distance and nature of the Squid Nebula have been difficult to determine. Still, one investigation suggests Ou4 really does lie within Sh2-129 some 2,300 light-years away. Consistent with that scenario, the cosmic squid would represent a spectacular outflow of material driven by a triple...

Explanation: Face-on spiral galaxy NGC 6946 and open star cluster NGC 6939 share this cosmic snapshot, composed with over 68 hours of image data captured with a small telescope on planet Earth. The field of view spans spans about 1 degree or 2 full moons on the sky toward the northern constellation Cepheus. Seen through faint interstellar dust clouds near the plane of our Milky Way galaxy, the stars of open cluster NGC 6939 are 5,600 light-years in the distance, near bottom right in the frame. Face-on spiral galaxy NGC 6946 is at top left, but lies some 22 million...

Explanation: If you know where to look, you can see a thermonuclear explosion from a white dwarf star. Possibly two. Such explosions are known as novas and the detonations are currently faintly visible with the unaided eye in Earth's southern hemisphere -- but are more easily seen with binoculars. Pictured, Nova Lupi 2025 (V462 Lupi) was captured toward the southern constellation of the Wolf (Lupus) last week near the central plane of our Milky Way galaxy. Nova Lupi 2025 was originally discovered on June 12 and peaked in brightness about a week later. Similarly, Nova Velorum 2025, toward the southern...

Explanation: Does the Milky Way always rise between these two rocks? No. Capturing this stunning alignment took careful planning: being in the right place at the right time. In the featured image taken in June 2024 from Otago, New Zealand, the bright central core of our Milky Way Galaxy, home to the many of our Galaxy's 400 billion stars, can be seen between two picturesque rocks spires. For observers in Earth's Northern Hemisphere, the core is only visible throughout the summer. As Earth orbits the Sun, different parts of the Milky Way become visible at different angles at different times...

Explanation: What do you see when you look into this sky? In the center, in the dark, do you see a night sky filled with stars? Do you see a sunset to the left? Clouds all around? Do you see the central band of our Milky Way Galaxy running down the middle? Do you see the ruins of an abandoned outpost on a hill? (The outpost is on Askold Island, Russia.) Do you see a photographer with a headlamp contemplating surreal surroundings? (The featured image is a panorama of 38 images taken last month and compiled into a Little Planet...

Explanation: It's raining stars. What appears to be a giant cosmic umbrella is now known to be a tidal stream of stars stripped from a small satellite galaxy. The main galaxy, spiral galaxy NGC 4651, is about the size of our Milky Way, while its stellar parasol appears to extend some 100 thousand light-years above this galaxy's bright disk. A small galaxy was likely torn apart by repeated encounters as it swept back and forth on eccentric orbits through NGC 4651. The remaining stars will surely fall back and become part of a combined larger galaxy over the next few...

Explanation: Are these trees growing on Mars? No. Groups of dark brown streaks have been photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost. The featured image was taken in 2008 April near the North Pole of Mars. At that time, dark sand on the interior of Martian sand dunes became more and more visible as the spring Sun melted the lighter carbon dioxide ice. When occurring near the top of a dune, dark sand may cascade down the dune leaving dark surface streaks -- streaks that might appear at first to be trees...

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....

Explanation: Big beautiful barred spiral galaxy Messier 109 is the 109th entry in Charles Messier's famous catalog of bright Nebulae and Star Clusters. You can find it just below the Big Dipper's bowl in the northern constellation Ursa Major. In fact, bright dipper star Phecda, Gamma Ursa Majoris, produces the glare at the upper right corner of this telescopic frame. M109's prominent central bar gives the galaxy the appearance of the Greek letter "theta", θ, a common mathematical symbol representing an angle. M109 spans a very small angle in planet Earth's sky though, about 7 arcminutes or 0.12 degrees. But...

Explanation: An interstellar expanse of glowing gas and obscuring dust presents a bird-like visage to astronomers from planet Earth, suggesting its popular moniker, the Seagull Nebula. This broadband portrait of the cosmic bird covers a 3.5-degree wide swath across the plane of the Milky Way, in the direction of Sirius, alpha star of the constellation of the Big Dog (Canis Major). The bright head of the Seagull Nebula is cataloged as IC 2177, a compact, dusty emission and reflection nebula with embedded massive star HD 53367. The larger emission region, encompassing objects with other catalog designations, is Likely part of...

Explanation: Is there a spiral galaxy in the center of this spiral galaxy? Sort of. Image data from the Hubble Space Telescope, the European Southern Observatory, and smaller telescopes on planet Earth are combined in this detailed portrait of face-on spiral galaxy Messier 61 (M61) and its bright center. A mere 55 million light-years away in the Virgo Cluster of Galaxies, M61 is also known as NGC 4303. It's considered to be an example of a barred spiral galaxy similar to our own Milky Way. Like other spiral galaxies, M61 also features sweeping spiral arms, cosmic dust lanes, pinkish star...