Bright Spots on Ceres

Dwarf planet Ceres has more than 130 bright areas, and most of them are associated with impact craters. Ceres has revealed some of its well-kept secrets in two studies. Two studies have been looking into the mystery behind these bright areas. One study identifies this bright material as a kind of salt, while the other study suggests the detection of ammonia-rich clays. The bright material is consistent with a type of magnesium sulfate called hexahydrite. A different type of magnesium sulfate is familiar on Earth as Epsom salt.

Researchers, using images from Dawn’s framing camera, suggest that these salt-rich areas were left behind when water-ice sublimated in the past. Impacts from asteroids would have unearthed the mixture of ice and salt. 

An image of Occator Crater (below) shows the brightest material on Ceres. Occator itself is 60 miles in diameter, and its central pit, covered by this bright material, measures about 6 miles wide. With its sharp rim and walls, it appears to be among the youngest features on the dwarf planet.

In the second nature study, members of the Dawn science team examined the composition of Ceres and found evidence for ammonia-rich clays. The ammonia ice by itself would evaporate on Ceres today because it is too warm. However, ammonia molecules could be stable if present in combination with other minerals. This 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. 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.

The data from our Dawn spacecraft was used for research.