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PASADENA, California — For months, the bright spots on Ceres' surface have puzzled people stuck on Earth.
After NASA's Dawn spacecraft snapped photos of 130 bright areas on the dwarf planet back in February, researchers and members of the general public alike offered theories that included everything from volcanoes to alien activity. Now, it appears scientists are rallying behind a less exotic culprit: salt.
NASA shared two new studies Wednesday that examined Ceres' composition and bright spots. By studying NASA's images, scientists in one study said they were able to identify the bright material as being hexahydrate — a magnesium sulfate similar to Earth's Epsom salt. They believe "salt-rich areas were left behind when water-ice sublimated in the past" and uncovered when asteroids impacted the planet, according to NASA. Most of the bright areas are in or near impact craters.
"The global nature of Ceres' bright spots suggests that this world has a subsurface layer that contains briny water-ice," lead author Andreas Nathues, of Germany's Max Planck Institute for Solar System Research, said in a statement.
Scientists haven't obtained definitive evidence of water on Ceres just yet, but reports from 2014> seem to indicate the presence of a water vapor. At about noon on the dwarf planet, a haze similar to the phenomenon of water vapor lifting off a comet's surface was observed taking place in Ceres' brightest crater called Occator. The haze disappeared by dusk and was still absent when the sun started to rise. "The Dawn science team is still discussing these results and analyzing data to better understand what is happening at Occator," Dawn principal investigator Chris Russell said in a statement.
Occator crater on #Ceres, with its bright beacons of mystery https://t.co/Vv4pDrYnP0pic.twitter.com/ge34qiJBfr
— NASA's Dawn Mission (@NASA_Dawn) December 4, 2015Another new piece of information — provided in the second study — is evidence from NASA's Dawn team that suggests the dwarf planet is home to ammonia-rich clays. Researchers identified the minerals by using data from the visible and infrared mapping spectrometer.
"The presence of ammoniated compounds raises the possibility that Ceres did not originate in the main asteroid belt between Mars and Jupiter, where it currently resides, but instead might have formed in the outer solar system," a statement from NASA reads. "Another idea is that Ceres formed close to its present position, incorporating materials that drifted in from the outer solar system — near the orbit of Neptune, where nitrogen ices are thermally stable."
While researchers are making progress to solve the mysteries of Ceres, many questions remain. The Dawn spacecraft is still orbiting Ceres at 240 miles above its surface. It is set to take more pictures of the dwarf planet in mid-December.
Both studies shared by NASA were published in the journal Nature.
