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The finding, published Wednesday in Nature, solves a long-standing mystery about water ice in comets. Scientists already knew that the coma... is dominated by water molecules.... "It is exciting because now we are starting to understand the upper dynamic layers of the comet and how they evolved." The surface of comet 67P, like most comets, is primarily covered by dark organic materials that appear almost black. That's because as comets fly toward the sun, they are exposed to warm temperatures that cause volatiles like water ice on their surface to sublimate - or go directly from solid to gas. What...

Researchers last got a signal from the Philae lander back in July, since then pinging it has resulted in no word from it—and i'’s all coming to a head now, says the ESA, because time is running out as the comet moves further and further away from the sun. With just a little time left, the plan is to try some off-label uses of Philae's momentum wheel. If the problem is that the lander is simply too dusty to power on, the hope is that spinning the wheel could clear off enough to let it wake itself up one last...

Explanation: This timely, telescopic, two panel mosaic spans about 10 full moons across planet Earth's predawn skies. Recorded as the year began from Tenerife, Canary Islands, near the top of the frame are the faint coma and tail of Comet Borrelly (P/19). A comet with a seven year orbital period, Borrelly's nucleus was visited by the ion propelled spacecraft Deep Space 1 near the beginning of the 21st century. Anchoring the scene at the bottom is brilliant star Arcturus (Alpha Bootes) and Comet Catalina (C/2013 US10) a first time visitor from the Oort Cloud. Catalina's yellowish dust tail extends below...

Explanation: A new year's treat for binoculars, as 2016 begins Comet Catalina (C/2013 US10) now sweeps through planet Earth's predawn skies near bright Arcturus, alpha star of Bootes. But this telescopic mosaic from December 21 follows the pretty tails of the comet across a field of view as wide as 10 full moons. The smattering of distant galaxies and faint stars in the background are in the constellation Virgo. Trailing behind the comet's orbit, Catalina's dust tail fans out below and left in the frame. Its ion tail is angled toward the top right, away from the Sun and buffeted...

Explanation: A crescent Moon and brilliant Venus met in predawn skies on December 7, a beautiful conjunction of planet Earth's two brightest celestial beacons after the Sun. Harder to see but also on the scene was Comet Catalina (C/2013 US10). The fainter comet clearly sporting two tails, lunar night side, bright sunlit lunar crescent, and brilliant morning star, are all recorded here by combining short and long exposures of the same field of view. Pointing down and right, Catalina's dust tail tends to trail behind the comet's orbit. Its ion tail, angled toward the top left of the frame, is...

Explanation: Comet Catalina is ready for its close-up. The giant snowball from the outer Solar System, known formally as C/2013 US10 (Catalina), rounded the Sun last month and is now headed for its closest approach to Earth in January. With the glow of the Moon now also out of the way, morning observers in Earth's northern hemisphere are getting their best ever view of the new comet. And Comet Catalina is not disappointing. Although not as bright as early predictions, the comet is sporting both dust (lower left) and ion (upper right) tails, making it an impressive object for binoculars...

Explanation: Not a bright comet, 67P/Churyumov-Gerasimenko now sweeps slowly through planet Earth's predawn skies near the line-up of planets along the ecliptic. Still, this composite of telescopic images follows the comet's progress as it moves away from the Sun beyond the orbit of Mars, from late September (left) through late November (far right). Its faint but extensive coma and tails are viewed against the colorful background of stars near the eastern edge of the constellation Leo. A year ago, before its perihelion passage, the comet was less active, though. Then the Rosetta mission's lander Philae made it's historic landing, touching...

Explanation: There she blows! A dramatic demonstration of how short-lived some comet jets can be was documented in late July by the robotic Rosetta spacecraft orbiting the nucleus of Comet 67P/Churyumov-Gerasimenko. The featured animation depicts changes in the rotating comet with three illuminating stills. Although the first frame shows nothing unusual, the second frame shows a sudden strong jet shooting off the 67P's surface only 20 minutes later, while the third frame -- taken 20 minutes after that -- shows but a slight remnant of the once-active jet. As comets near the Sun, they can produce long and beautiful tails...

Astronomers initially thought the object was an asteroid when they spotted it in early October, and named it Asteroid 2015 TB145. But using the US space agency's Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, experts "have determined that the celestial object is more than likely a dead comet that has shed its volatiles after numerous passes around the sun," NASA's Jet Propulsion Laboratory said in a statement late Friday. ... The space rock has already grabbed attention with its unusually high speed and big size, about as large as a football stadium at 2,000 feet (600 meters) in diameter....

This single frame Rosetta navigation camera image of Comet 67P/Churyumov-Gerasimenko was taken on 7 July 2015 from a distance of 154 km from the comet centre. The image has a resolution of 13.1 m/pixel and measures 13.4 km across. Credit: ESA/Rosetta/NAVCAM --------------------------------------------------------------------------------------------------------------------------------------------- Stunned scientists announced Wednesday the unexpected discovery of large quantities of oxygen on a comet which streaked past the Sun in August with a European spacecraft in tow. The find came as a "big surprise", and challenges mainstream theories on the formation of our Solar System, said scientist Andre Bieler of the University of Michigan. Measurements suggested that...

A comet with the nickname Happy Hour leaves a boozy trail equivalent to "500 bottles of wine per second" in its wake as it shoots through space. Scientists studying the comet, known as Lovejoy, have found its glowing trail is made up of alcohol and sugar. A study published by a group of scientists from NASA and European agencies observed the unusual comet as it rocketed alongside the sun on January 30, NASA reports. "You have alcohol and sugar, so that can lead to a 'happy hour' name, but I would not recommend anyone drink this water," team researcher Darek...

Sergio Frau suspects Plato was writing about a tidal wave on Sardinia... Writer and journalist Sergio Frau is another. After researching the island for a decade, Frau suspects a mysterious disaster that devastated Sardinia 3,200 years ago was in fact a tidal wave, which boosts the theory that Sardinia and Atlantis are one and the same, reports the Guardian. Stefano Tinti, an expert on tidal waves who recently visited the island with Frau along with a dozen other experts, says 350 tidal waves have occurred in the Mediterranean over the last 2,500 years and one might explain why all of...

How would you like to see one of the most famous comets with your own eyes? Comet 67P/Churyumov-Gerasimenko plies the morning sky, a little blot of fuzzy light toting an amazing visitor along for the ride — the Rosetta spacecraft. When you look at the coma and realize a human-made machine is buzzing around inside, it seems unbelievable. If you have a 10-inch or larger telescope, or you’re an experienced amateur with an 8-inch and pristine skies, 67P is within your grasp. The comet glows right around magnitude +12, about as bright as it will get this apparition. Periodic comets...

Explanation: Will Comet Catalina become visible to the unaided eye? Given the unpredictability of comets, no one can say for sure, but it seems like a good bet. The comet was discovered in 2013 by observations of the Catalina Sky Survey. Since then, Comet C/2013 US10 (Catalina) has steadily brightened and is currently brighter than 8th magnitude, making it visible with binoculars and long-duration camera images. As the comet further approaches the inner Solar System it will surely continue to intensify, possibly becoming a naked eye object sometime in October and peaking sometime in late November. The comet will reside...

Explanation: This dramatic outburst from the nucleus of Comet 67P/Churyumov-Gerasimenko occured on August 12, just hours before perihelion, its closest approach to the Sun. Completing an orbit of the Sun once every 6.45 years, perihelion distance for this periodic comet is about 1.3 astronomical units (AU), still outside the orbit of planet Earth (at 1 AU). The stark image of the 4 kilometer wide, double-lobed nucleus in bright sunlight and dark shadows was taken by the Rosetta spacecraft's science camera about 325 kilometers away. Too close to see the comet's growing tail, Rosetta maintains its ringside seat to watch the...

Explanation: Dusty debris from periodic Comet Swift-Tuttle was swept up by planet Earth this week. Vaporized by their passage through the dense atmosphere at 59 kilometers per second, the tiny grains produced a stream of Perseid meteors. A bright, colorful Perseid meteor flash was captured during this 20 second exposure. It made its ephemeral appearance after midnight on August 12, in the moonless skies over the broad granite dome of Enchanted Rock State Natural Area, central Texas, USA. Below the Perseid meteor, trees stand in silhouette against scattered lights along the horizon and the faint Milky Way, itself cut by...

Popular Science (8/11, Fecht) reports that on July 29, the Rosetta spacecraft was able to capture what the ESA called a “dramatic outburst” from Comet 67P, which was strong enough to affect the solar wind. The article notes that the ESA said that “unpredictable outbursts” like this one are occurring more frequently as the comet reaches perihelion, or its closest point to the sun in its orbit, on August 13.

In a sequence of images taken by Rosetta’s scientific camera OSIRIS, the brilliant, well-defined jet erupts from the side of the comet’s neck in the Anuket region. It was first seen in a photo taken at 8:24 a.m. CDT, but not in one taken 18 minutes earlier, and had faded significantly in an image captured 18 minutes later. The camera team estimates the material in the jet was traveling at a minimum of 22 mph (10 meters/sec), but possibly much faster. It’s the brightest jet ever seen by Rosetta. Normally, the camera has to be set to overexpose 67P/C-G’s nucleus...

After first touching down, Philae was able to use its gas-sniffing Ptolemy and COSAC instruments to determine the makeup of the comet’s atmosphere and surface materials. COSAC analyzed samples that entered tubes at the bottom of the lander and found ice-poor dust grains that were rich in organic compounds containing carbon and nitrogen. It found 16 in all including methyl isocyanate, acetone, propionaldehyde and acetamide that had never been seen in comets before. Ptolemy sampled the atmosphere entering tubes at the top of the lander and identified water vapor, carbon monoxide and carbon dioxide, along with smaller amounts of carbon-bearing...

Call it the comet that squeaked by most northern skywatchers. Comet C/2014 Q1 PanSTARRS barely made an appearance at dawn in mid-June when it crept a few degrees above the northeastern horizon at dawn. Only a few determined comet watchers spotted the creature. Two weeks later in early July it slipped into the evening and brightened to magnitude +4. But decreasing elongation from the Sun and bright twilight made it virtually impossible to see. Now it’s returned — with three tails! After taunting northerners, it’s finally come out of hiding, climbing into the western sky during evening twilight for observers...