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This week NASA's Dawn space probe swooped within 22 miles of the surface of Ceres, the dwarf planet that's the largest object in the asteroid belt between Mars and Jupiter. NASA's JPL reports: In more than three years of orbiting Ceres, Dawn's lowest altitude before this month was 240 miles (385 kilometers), so the data from this current orbit bring the dwarf planet into much sharper focus... "[T]he results are better than we had ever hoped," said Dawn's chief engineer and project manager, Marc Rayman, of NASA's Jet Propulsion Laboratory, Pasadena, California. "Dawn is like a master artist, adding rich details to the otherworldly beauty in its intimate portrait of Ceres."
EarthSky reports NASA captured an up-close glimpse of those tantalizing bright spots on Ceres: The spots, evaporate deposits composed of sodium carbonate, are thought to be left over from when water came up to the surface from deeper below and then evaporated in the extremely tenuous and sporadic water vapor "atmosphere." That water could be either from a shallow sub-surface reservoir or from a deeper reservoir of salty brines percolating upward through fractures. The deposits in Occator Crater are the largest and brightest of these deposits. As with many discoveries in planetary science, they were completely unexpected, and show that Ceres is not just an inert ball of rock and ice.
Slashdot reader thegameiam adds: Ceres may have more fresh water than exists on Earth. Perhaps this would make colonization of the asteroid belt more of a possibility?

Scientists at Wits University in Johannesburg, South Africa say they've discovered evidence of a "lost continent" beneath the island of Mauritius in the Indian Ocean. According to EarthSky, the evidence of the "lost continent" may be leftover from the breakup of the ancient supercontinent Gondwana, which started to break up around 200 million years ago. The evidence itself "takes the form of ancient zircon minerals found in much-younger rocks." From the report: Geologist Lewis Ashwal of Wit University led a group studying the mineral zircon, found in rocks spewed up by lava during volcanic eruptions. Zircon minerals contain trace amounts of radioactive uranium, which decays to lead and can thus be accurately dated. Ashwal and his colleagues say they've found remnants of this mineral far too old to have originated on the relatively young island of Mauritius. They believe their work shows the existence of an ancient continent, which may have broken off from the island of Madagascar, when Africa, India, Australia and Antarctica split up and formed the Indian Ocean. Ashwal explained in a statement: "Earth is made up of two parts -- continents, which are old, and oceans, which are "young." On the continents you find rocks that are over four billion years old, but you find nothing like that in the oceans, as this is where new rocks are formed. Mauritius is an island, and there is no rock older than 9 million years old on the island. However, by studying the rocks on the island, we have found zircons that are as old as 3 billion years. The fact that we have found zircons of this age proves that there are much older crustal materials under Mauritius that could only have originated from a continent." The study has been published in the journal Nature Communications.

On Monday at 7:47 A.M. EST, an asteroid thought to be between 36 and 111 feet wide passed roughly 120,000 miles from Earth -- and astronomers didn't spot it until Saturday. Smithsonian reports: According to astronomer Eric Edelman at the Slooh Observatory, 2017 AG13 is an Aten asteroid, or a space rock with an orbital distance from the sun similar to that of Earth. AG13 also has a particularly elliptical orbit, which means that as it circles the sun it also crosses through the orbits of both Venus and Earth. Lucky for us, 2017 AG13 wasn't a planet killer; according to Wall, the asteroid was in the size range of the space rock that exploded in Earth's atmosphere over Chelyabinsk, Russia, in February, 2013. According to Deborah Byrd at EarthSky, that meteor exploded 12 miles in the atmosphere, releasing 30 times the energy of the Hiroshima nuclear bomb. Not only did it break windows in six cities, it also sent 1,500 people to the hospital. That meteor also came out of the blue, and researchers are still trying to figure out its orbit and track down its origins. While 2017 AG13 would have caused minor damage if it hit Earth, the close call highlights the dangers of asteroids.

An anonymous reader quotes a report from EarthSky: NASA and the National Snow and Ice Data Center (NSIDC) said on September 15, 2016 that summertime Arctic sea ice appears to have reached its annual minimum on September 10. With fall approaching and temperatures in the Arctic dropping, it's unlikely more ice will melt, and so the 2016 Arctic sea ice minimum extent will likely be tied with 2007 for the second-lowest yearly minimum in the satellite record. Satellite data showed this year's minimum at 1.60 million square miles (4.14 million square km). NASA said in a statement: "Since satellites began monitoring sea ice in 1978, researchers have observed a steep decline in the average extent of Arctic sea ice for every month of the year [...] The sea ice cover of the Arctic Ocean and surrounding seas helps regulate the planet's temperature, influences the circulation of the atmosphere and ocean, and impacts Arctic communities and ecosystems. Arctic sea ice shrinks every year during the spring and summer until it reaches its minimum yearly extent. Sea ice regrows during the frigid fall and winter months, when the sun is below the horizon in the Arctic." The NASA/NSIDC statement explained why the melt of Arctic sea ice surprised scientists in 2016. For one thing, it changed pace several times: "The melt season began with a record low yearly maximum extent in March and a rapid ice loss through May. But in June and July, low atmospheric pressures and cloudy skies slowed down the melt. Then, after two large storms went across the Arctic basin in August, sea ice melt picked up speed through early September." NASA posted an animation on YouTube that "shows the evolution of the Arctic sea ice cover from its wintertime maximum extent, which was reached on Mar. 24, 2016, and was the lowest on record for the second year in a row, to its apparent yearly minimum, which occurred on Sept. 10, 2016, and is the second lowest in the satellite era."

An anonymous reader quotes a report from EarthSky: NASA and the National Snow and Ice Data Center (NSIDC) said on September 15, 2016 that summertime Arctic sea ice appears to have reached its annual minimum on September 10. With fall approaching and temperatures in the Arctic dropping, it's unlikely more ice will melt, and so the 2016 Arctic sea ice minimum extent will likely be tied with 2007 for the second-lowest yearly minimum in the satellite record. Satellite data showed this year's minimum at 1.60 million square miles (4.14 million square km). NASA said in a statement: "Since satellites began monitoring sea ice in 1978, researchers have observed a steep decline in the average extent of Arctic sea ice for every month of the year [...] The sea ice cover of the Arctic Ocean and surrounding seas helps regulate the planet's temperature, influences the circulation of the atmosphere and ocean, and impacts Arctic communities and ecosystems. Arctic sea ice shrinks every year during the spring and summer until it reaches its minimum yearly extent. Sea ice regrows during the frigid fall and winter months, when the sun is below the horizon in the Arctic." The NASA/NSIDC statement explained why the melt of Arctic sea ice surprised scientists in 2016. For one thing, it changed pace several times: "The melt season began with a record low yearly maximum extent in March and a rapid ice loss through May. But in June and July, low atmospheric pressures and cloudy skies slowed down the melt. Then, after two large storms went across the Arctic basin in August, sea ice melt picked up speed through early September." NASA posted an animation on YouTube that "shows the evolution of the Arctic sea ice cover from its wintertime maximum extent, which was reached on Mar. 24, 2016, and was the lowest on record for the second year in a row, to its apparent yearly minimum, which occurred on Sept. 10, 2016, and is the second lowest in the satellite era."

An anonymous reader writes: If you want to look out into the Universe, all you need to do is gather the light it gives off. Unless, of course, there's something in the way. For about 20% of the sky, that's exactly the story. In our own Milky Way galaxy, the neutral gas and dust block most of the visible light everywhere we look, preventing us from observing the Universe beyond. However, although the gas and dust might block visible light, longer wavelengths like radio and infrared can pass right through. Recently NASA's Wide-field Infrared Survey Explorer (WISE) mission mapped the entire sky in the infrared, including the entire galactic plane. It not only found many background galaxies, but it gave us a new window into what's possible. Perhaps, with future missions, we'll discover the cause of the "great attractor" phenomenon after all.

Taco Cowboy writes "NASA's WISE (Wide-field Infrared Survey Explorer) satellite was looking at a distant galaxy, some 3.8 billion light-years away, and saw something rather unusual. At first they thought that they saw a galaxy was forming new stars at a furious rate, but upon closer checking, they found that they were seeing two supermassive black holes spiraling closer and closer to each other. The dance of this black hole duo started out slowly, with the objects circling each other at a distance of about a few thousand light-years. As the black holes continued to spiral in toward each other, they were separated by just a few light-years. Supermassive black holes at the cores of galaxies typically shoot out pencil-straight jets, but in this case, the jet showed a zig-zag pattern. According to the scientists, a second massive black hole could, in essence, be pushing its weight around to change the shape of the other black hole's jet. Visible-light spectral data from the Gemini South telescope in Chile showed similar signs of abnormalities, thought to be the result of one black hole causing disk material surrounding the other black hole to clump. Together, these and other signs point to what is probably a fairly close-knit set of circling black holes, though the scientists can't say for sure how much distance separates them."

New submitter turp182 writes to remind us that the Perseid meteor shower will be visible this weekend (Aug. 11-13). Astronomers are anticipating the Perseid shower being the best of the year, forecasting rates as high as 100 meteors per hour. They'll be visible through the night, but viewing will be at its best in the hours before dawn. NASA points out that this shower will be particularly interesting thanks to appearances from Venus, Jupiter, and the crescent moon. "On August 11th, a 33% crescent Moon will glide by Jupiter, temporarily forming a bright pair directly above brilliant Venus. Red-giant star Aldebaran will be there, too, adding a splash of color to the gathering. On August 12th, the narrowing 24% crescent Moon will drop down between Jupiter and Venus. Together they make a bright 3-point line in the sky, frequently bisected by shooting stars. On August 13th, with the shower just beginning to wane, the planets put on their best show yet: The 17% crescent moon will pass less than 3 degrees from Venus as Jupiter hovers overhead. Sky watchers say there's nothing prettier than a close encounter between the slender crescent Moon and Venus--nothing, that is, except for the crescent Moon, Venus and a flurry of Perseids."

Larry Sessions, a columnist for Earth & Sky, has suggested in his blog that the gamma-ray event whose radiation reached us a few hours before Arthur C. Clarke died, and which occurred 7.5 billion years ago, be named the Clarke Event. The outburst, which produced enough visible light to render it a naked-eye object across half the universe, is officially designated GRB 080319B. What more fitting tribute to Clarke than to associate his name with the greatest bang since the big one? Sessions suggests writing to any astronomers, heads of physics departments, or planetarium operators you know and talking up the proposal.

mdsolar writes "If you want to take a chance on the Lyrid Meteor Shower you should be looking this weekend. This shower is usually a quiet one but can result is spectacular displays from time to time. Earth & Sky gives viewing times as the very early hours of Sunday and Monday morning. The moon will have set by then."