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Explanation: Yesterday there was a total solar eclipse visible only at the end of the Earth. To capture the unusual phenomenon, airplanes took flight below the clouded seascape of Southern Ocean. The featured image shows one relatively spectacular capture where the bright spot is the outer corona of the Sun and the eclipsing Moon is seen as the dark spot in the center. A wing and engine of the airplane are visible across the left and bottom of the image, while another airplane observing the eclipse is visible on the far left. The dark area of the sky surrounding the...

Explanation: In this snapshot from November 18, the Full Moon was not far from Earth's shadow. In skies over Sicily the brightest lunar phase was eclipsed by passing clouds though. The full moonlight was dimmed and momentarily diffracted by small but similar sized water droplets near the edges of the high thin clouds. The resulting iridescence shines with colors like a lunar corona. On that night, the Full Moon was also seen close to the Pleiades star cluster appearing at the lower left of the iridescent cloud bank. The stars of the Seven Sisters were soon to share the sky...

Comet Leonard, also known as C/2021, will make its closest approach to Earth on Dec. 12, according to NASA. EarthSky describes C/2021 A as “likely to be 2021’s best comet, and its brightest comet by year’s end.” Leonard is actually already visible in the sky and can be seen the first two weeks of December in the east before the sun rises. NASA says you can spot it by looking between the Big Dipper’s handle and Arcturus, the latter of which is one of the brightest stars in the night sky. Then, as Leonard makes its closest encounter with our...

Explanation: Sweeping through northern predawn skies, on November 24 Comet Leonard (C/2021 A1) was caught between two galaxies in this composite telescopic image. Sporting a greenish coma the comet's dusty tail seems to harpoon the heart of NGC 4631 (top) also known as the Whale Galaxy. Of course NGC 4631 and NGC 4656 (bottom, aka the Hockey Stick) are background galaxies some 25 million light-years away. On that date the comet was about 6 light-minutes from our fair planet. Its closest approach to Earth (and even closer approach to Venus) still to come, Comet Leonard will grow brighter in December....

Explanation: Grand spiral galaxies often seem to get all the glory, flaunting their young, bright, blue star clusters in beautiful, symmetric spiral arms. But small galaxies form stars too, like nearby NGC 6822, also known as Barnard's Galaxy. Beyond the rich starfields in the constellation Sagittarius, NGC 6822 is a mere 1.5 million light-years away, a member of our Local Group of galaxies. A dwarf irregular galaxy similar to the Small Magellanic Cloud, NGC 6822 is about 7,000 light-years across. Brighter foreground stars in our Milky Way have a spiky appearance. Behind them, Barnard's Galaxy is seen to be filled...

Explanation: What causes a blue band to cross the Moon during a lunar eclipse? The blue band is real but usually quite hard to see. The featured HDR image of last week's lunar eclipse, however -- taken from Yancheng, China -- has been digitally processed to equalize the Moon's brightness and exaggerate the colors. The gray color of the bottom right is the Moon's natural color, directly illuminated by sunlight. The upper left part of the Moon is not directly lit by the Sun since it is being eclipsed -- it in the Earth's shadow. It is faintly lit, though,...

Explanation: What's that moving across the sky? A planet just a bit too faint to see with the unaided eye: Uranus. The gas giant out past Saturn was tracked earlier this month near opposition -- when it was closest to Earth and at its brightest. The featured video captured by the Bayfordbury Observatory in Hertfordshire, UK is a four-hour time-lapse showing Uranus with its four largest moons in tow: Titania, Oberon, Umbriel and Ariel. Uranus' apparent motion past background stars is really dominated by Earth's own orbital motion around our Sun. The cross seen centered on Uranus is called a...

NASA abruptly called off a spacewalk shortly before it was set to begin Tuesday morning after receiving a notification that debris could threaten the astronauts outside the International Space Station. The notice came just two weeks after Russia fired a missile that destroyed a dead satellite polluting low Earth orbit with more than 1,500 pieces of debris that forced the astronauts and cosmonauts to evacuate the space station and board their spacecraft in case they had to flee. NASA astronauts Thomas Marshburn and Kayla Barron had been scheduled to step outside the orbiting laboratory at about 7:10 a.m. Eastern time...

Explanation: What created the strange spiral structure on the upper left? No one is sure, although it is likely related to a star in a binary star system entering the planetary nebula phase, when its outer atmosphere is ejected. The huge spiral spans about a third of a light year across and, winding four or five complete turns, has a regularity that is without precedent. Given the expansion rate of the spiral gas, a new layer must appear about every 800 years, a close match to the time it takes for the two stars to orbit each other. The star...

Explanation: This high cliff occurs not on a planet, not on a moon, but on a comet. It was discovered to be part of the dark nucleus of Comet Churyumov-Gerasimenko (CG) by Rosetta, a robotic spacecraft launched by ESA that rendezvoused with the Sun-orbiting comet in 2014. The ragged cliff, as featured here, was imaged by Rosetta in 2014. Although towering about one kilometer high, the low surface gravity of Comet CG would likely make it an accessible climb -- and even a jump from the cliff survivable. At the foot of the cliff is relatively smooth terrain dotted with...

Explanation: Big, beautiful spiral galaxy M101 is one of the last entries in Charles Messier's famous catalog, but definitely not one of the least. About 170,000 light-years across, this galaxy is enormous, almost twice the size of our own Milky Way. M101 was also one of the original spiral nebulae observed by Lord Rosse's large 19th century telescope, the Leviathan of Parsontown. Assembled from 51 exposures recorded by the Hubble Space Telescope in the 20th and 21st centuries, with additional data from ground based telescopes, this mosaic spans about 40,000 light-years across the central region of M101 in one of...

Explanation: Rain clouds passed and the dome of the Lick Observatory's 36 inch Great Refractor opened on November 19. The historic telescope was pointed toward a partially eclipsed Moon. Illuminated by dim red lighting to preserve an astronomer's night vision, telescope controls, coordinate dials, and the refractor's 57 foot long barrel were captured in this high dynamic range image. Visible beyond the foreshortened barrel and dome slit, growing brighter after its almost total eclipse phase, the lunar disk created a colorful corona through lingering clouds. From the open dome, the view of the clearing sky above includes the Pleiades star...

Explanation: Shaped like a cone tapering into space, the Earth's dark central shadow or umbra has a circular cross-section. It's wider than the Moon at the distance of the Moon's orbit though. But during the lunar eclipse of November 18/19, part of the Moon remained just outside the umbral shadow. The successive pictures in this composite of 5 images from that almost total lunar eclipse were taken over a period of about 1.5 hours. The series is aligned to trace part of the cross-section's circular arc, with the central image at maximum eclipse. It shows a bright, thin sliver of...

Explanation: Have you ever seen the Pleiades star cluster? Even if you have, you probably have never seen it as large and clear as this. Perhaps the most famous star cluster on the sky, the bright stars of the Pleiades can be seen without binoculars from even the depths of a light-polluted city. With a long exposure from a dark location, though, the dust cloud surrounding the Pleiades star cluster becomes very evident. The featured exposure, taken from Florida, USA, covers a sky area several times the size of the full moon. Also known as the Seven Sisters and M45,...

Taking aim at a distant asteroid, SpaceX fired a small NASA probe into space early Wednesday, setting up a head-on 15,000 mph impact next September to test the feasibility of nudging a threatening body off course long before it could crash into Earth. The $330 million Double Asteroid Redirection Test, or DART, the first test flight in a NASA planetary defense initiative, "will be historic," said Tom Statler, mission program scientist at NASA Headquarters. "For the first time, humanity will change the motion of a natural celestial body in space." Perched atop a SpaceX Falcon 9 rocket, the DART mission...

Explanation: Why are the regions above sunspots so hot? Sunspots themselves are a bit cooler than the surrounding solar surface because the magnetic fields that create them reduce convective heating. It is therefore unusual that regions overhead -- even much higher up in the Sun's corona -- can be hundreds of times hotter. To help find the cause, NASA directed the Earth-orbiting Nuclear Spectroscopic Telescope Array (NuSTAR) satellite to point its very sensitive X-ray telescope at the Sun. Featured here is the Sun in ultraviolet light, shown in a red hue as taken by the orbiting Solar Dynamics Observatory (SDO)....

The launch readiness date for the James Webb Space Telescope is moving to no earlier than December 22 to allow for additional testing of the observatory, following a recent incident that occurred during Webb’s launch preparations. The incident occurred during operations at the satellite preparation facility in Kourou, French Guiana, performed under Arianespace overall responsibility. Technicians were preparing to attach Webb to the launch vehicle adapter, which is used to integrate the observatory with the upper stage of the Ariane 5 rocket. A sudden, unplanned release of a clamp band – which secures Webb to the launch vehicle adapter –...

The long-awaited launch of the nearly $10 billion James Webb Space Telescope is slipping at least four days, from December 18 to no earlier than December 22, after an incident during processing in French Guiana that briefly jostled the costly observatory.... ...The incident occurred in a processing facility at the Ariane 5 launch site in Kourou, French Guiana. A high-tension "clamp band," used to attach the telescope to an adapter that will, in turn, be mounted atop the rocket's upper stage, suddenly released on its own, briefly shaking the observatory....

On a winter morning in 2013, a meteor the size of a four-story building screamed across the country, exploding near the city of Chelyabinsk and injuring more than 1,600 people amid widespread property damage. The chunk of rock and iron, which was 60 feet across, served as a violent reminder that Earth, bombarded daily with tons of space-going debris, periodically intersects with large planet killers—and a significant portion of those remain undocumented. After years of study and discussion, NASA is ready to launch its first effort to spare Earth the kind of calamity that extinguished the dinosaurs, crashing a space...

Explanation: Why is the Moon on top of this building? Planning. It took the astrophotographer careful planning -- including figuring out exactly where to place the camera and exactly when to take the shot -- to create this striking superposition. The single image featured was taken in the early morning hours of November 19, near the peak of the partial lunar eclipse that was occurring as the Moon passed through the Earth's shadow. At this time, almost the entire Moon -- 99.1 percent of its area -- was in the darkest part of the Earth's shadow. The building is the...