Explanation: What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraf...
Explanation: What color is the Moon? It depends on the night -- and the time. Outside of the Earth's atmosphere, the dark Moon, which shines by reflected sunlight, appears a magnificently brown-tinged gray. The featured image highlights a collection of apparent colors of the...
Explanation:What spooky planet is this? Planet Earth on a dark and stormy night, of course. The ghostly scene was photographed at Hverir, a geothermally active area found along northeastern Iceland's volcanic landscape. Triggered by solar activity, geomagnetic storms have unleashed energetic particles trapped in Earth's magnetic field. Penetrating the planet's upper atmosphere at high latitudes, the particles create auroral displays in the starry night sky. Ghostly towers of steam and gas are venting from local fumaroles to dance against the eerie, greenish northern lights. For now, auroral activity on planet Earth remains in a high state as the Sun is only in early phases of decline from the peak of its solar activity cycle. And soon, other ghostly apparitions may dance in your neighborhood. Happy Halloween!
Explanation: Spooky shapes seem to haunt this dusty expanse, drifting through the night in the royal constellation Cepheus. Of course, the shapes are cosmic dust clouds visible in dimly reflected starlight. Far from your own neighborhood, they lurk above the plane of the Mil...
Explanation: That's no moon. But you could be forgiven for thinking it was a crescent Moon in the sky. It is a lesser known fact that Venus also has phases. (What about other planets?) The featured image shows Venus seen almost directly between the Sun and the Earth. This ha...
Explanation: Jupiter is one of the least lonely planets in the Solar System, at least when it comes to natural satellites. 115 moons have been discovered orbiting Jupiter so far! (Saturn has the most with 293, but who’s counting.) Ganymede and Io, two of Jupiter’s Galilean m...
Explanation: Sometimes it's night on the ground but day in the air. As the Earth rotates to eclipse the Sun, sunset rises upfrom the ground. Therefore, at sunset on the ground, sunlight still shines on clouds above. Under usual circumstances, a prett...
Explanation: The Great Nebula in Orion, an immense, nearby starbirth region, is one the most famous of all astronomical nebulas. Here, glowing gas surrounds hot young stars at the edge of an immense interstellar molecular cloud only 1500 light-years away. In the featured dee...
Explanation: The Great Nebula in Orion, an immense, nearby starbirth region, is one the most famous of all astronomical nebulas. Here, glowing gas surrounds hot young stars at the edge of an immense interstellar molecular cloud only 1500 light-years away. In the featured dee...
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 ho...
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 spacecraf...
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 sce...
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: ...
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 mul...
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, ju...
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 Tr...
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...
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.
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...
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 dis...
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 zodiaca...
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.
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...
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.
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 ha...
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 tempera...
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 a...
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 spacecra...
Explanation: 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 ex...
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