When NASA’s Dawn mission witnessed Ceres’ weird bright spots up-close for the first time, planetary scientists were baffled. What material could produce such a bright feature on an otherwise grey surface? Now, a year since the probe arrived in orbit around the dwarf planet, scientists may be closing in on an answer.

Ian O'Neill news.discovery.com 3-16-16

However, it’s not Dawn that has found the latest clue as to what these bright patches could be; it was a powerful observatory on Earth that noticed very slight changes as Ceres’ surface is gently heated by the sun.

The bright spots in question are mainly clustered inside a large crater called Occator. Now that Dawn is in its lowest mapping orbit around the small world nestled in the Main Asteroid Belt (between the orbits of Mars and Jupiter), zipping across the cratered landscape at an altitude of only 240 miles, it has captured wonderfully detailed observations of the crater’s floor. The bright feature is actually a cluster of bright spots with diffuse, almost powder-like material surrounding the brightest patches.

The leading theory, so far, is that it’s an icy material such as water ice, but some kind of mineral deposit is also a possibility. Now, with the help of the HARPS spectrograph attached to the ESO 3.6-meter telescope at La Silla, Chile, it seems the ice theory has just become a whole lot stronger. [...]
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