The Brightest Spot on Ceres . ... Exploring Ceres from orbit since March, the Dawn spacecraft's camera has revealed about 130 or so mysterious bright spots, mostly associated with impact craters scattered around the small world's otherwise dark surface. ... A study now finds the bright spot's reflected light properties are probably most consistent with a type of magnesium sulfate called hexahydrite. ... In mid-December, Dawn will begin taking observations from its closest Ceres mapping orbit. ...