'Huge craters missing from dwarf planet Ceres'

Washington, July 27: In an intriguing find, scientists associated with SA’s Dawn spacecraft have discovered a mysterious disappearance of a significant number of large craters on dwarf planet Ceres, indicating something has happened to it. SA’s Dawn spacecraft arrived to orbit Ceres in March 2015 and mission scientists expected to find a heavily-cratered body generally resembling the protoplanet Vesta - Dawn’s previous port of call. Instead, as the spacecraft drew near to Ceres, a somewhat different picture began to emerge: Something has happened to Ceres to remove its biggest impact basins. Now, a team of Dawn scientists led by Simone Marchi from the Southwest Research Institute in Boulder, Colorado suggest that Ceres has experienced significant geological evolution, possibly erasing the large basins. “We concluded that a significant population of large craters on Ceres has been obliterated beyond recognition over geological time scales, which is likely the result of Ceres’ peculiar composition and interl evolution,” Marchi explained in a paper. According to David Williams from Arizo State University, “When we first starting looking at Ceres images, we noticed that there weren’t any really large impact basins on the surface.” None are larger than 285 km across. This presents a mystery, he says, because Ceres must have been struck by large asteroids many times over its 4.5-billion-year history. “Even Vesta, only about half of Ceres’ size, has two big basins at its south pole. (IANS)