Those bright spots on micro planet Ceres most likely salt pans

After analyzing recent imagery provided by Dawn spacecraft, German scientists concluded that the two bright spots are shrouded in afternoon haze on a regular basis. Following the discovery of the second bright spot, Max Planck scientist Andreas Nathues said: “The brightest spot continues to be too small to resolve with our camera, but despite its size it is brighter than anything else on Ceres”. “The simplest scenario is that the sublimation process of water ice starts after a mixture of ice and salt minerals is exposed by an impact, which penetrates the insulating dark upper crust”, the researchers write in their Nature paper.

We’ve been wondering about those bright, white spots on the dwarf planet Ceres ever since the Dawn spacecraft arrived there in March. Two of the spots are far brighter than the rest, the most dazzling of which is located at the bottom of a 2-mile-deep crater called Occator.

Dwarf planet Ceres is shown in these false-color renderings, which highlight differences in surface materials. The spots are mostly linked to impact craters and are much brighter compared to the surface of Ceres as a whole. Surprisingly, they found evidence of ammonia-rich clays, or ammoniated phyllosilicates, on the surface, indicating that Ceres might have formed somewhere near the orbit of Neptune where nitrogen ices are thermally stable.

A NASA report states that the team reviewed images taken with Dawn’s framing camera and suggested that the salt deposits were likely left behind when water-ice sublimated sometime in the past. Although another study released today hints that Ceres has little if any water on its exterior, together the findings suggest that the small world may harbor significant amounts of water ice just below its surface.

“What we’re seeing are salts in a solid state”. Predominantly dark, the bright spots offer a diverse feature to Ceres, being spread all around the planet. “Consequently, we think that this material originated in the outer cold solar system”, lead author Maria Cristina De Sanctis, a scientist at the National Institute of Astrophysics in Rome, said, in a statement.

In a pair of studies in the respected science journal Nature, researchers used data from Ceres and suggested the weird glow was caused by light reflecting off salty ice. The instrument’s data can shed light on Ceres’ surface composition, based on reflectance characteristics, NASA officials have said.

That could mean that instead of forming in its current orbit in the asteroid belt, Ceres could have been born in the outer solar system; or, alternatively, collisions with stuff drifting in from the outer solar system could have brought the ammonia.

The phenomenon is quite common in comets, but was never witnessed over a dwarf planet like Ceres. Specifically, they focused on the spectra, or chemical fingerprints, of carbonaceous chondrites, a type of carbon-rich meteorite thought to be relevant analogues for the dwarf planet. The most likely explanation is that ice is sublimating from the surface of Ceres under the Sun’s piercing, daytime glare, and settling back down in the evening.

As of this week, Dawn has reached its final orbital altitude at Ceres, about 240 miles (385 kilometers) from the surface of the dwarf planet.