Ceres' bright spots show the dwarf planet is active

Astronomers believe there is still natural activity occurring on the dwarf planet Ceres.
By Joseph Scalise | Dec 17, 2017
Bright spots on the dwarf planet Ceres' suggest the barren world is still active, according to a new study set to be published in the journal Icarus.

This finding comes from researchers at the California Institute of Technology, who discovered that the distant world's bright patches may sit over pools of salty water, which in turn may be the remnants of an ancient, subsurface ocean.

To discover this, the team categorized the more than 300 bright patches on Ceres' surface -- which were first spotted by the Dawn spacecraft in 2015 -- into four groups, and then looked at the factors that could be behind the spots' differences.

All of the spots are in or around craters, and the most reflective material sits at the bottom of such formations. In fact, some of the first spots found sit at the bottom of the 57-mile-wide Occator Crater. The formation has two bright areas, Cerealia Facula in the center and Vinalia Faculae to the east. Cerealia Faculae is a collection of the brightest material on Ceres spread over a 6-mile-wide pit, while Vinalia Faculae is fainter and slightly less reflective.

There are also two other types of bright material on the body. One type sits on the rim of craters and streaks downwards, while the other is spread around crater edges.

Freshly exposed material is commonly bright. However, in the case of Ceres', the spots slowly mixed with dark material over millions of years and dimmed most regions. Though many researchers have debated the source of the bright spots, the team in the study believes they originated from pockets of brine beneath the surface that were left over from a past liquid layer.

If that is true, it would mean that Ceres' ocean slowly froze over time before leaving behind the brine pockets. As the spots are discontinuous, the team suspects such areas are isolated pools rather than a complete liquid layer. They also think the briny liquid came to the surface when expanding ice caused the cooling liquid upwards. However, there is also they were driven to the surface when chance impactors squeezed the pockets. Even so, the new findings suggest the dwarf planet is not as dead as it appears.

 

"The mysterious bright spots on Ceres, which have captivated both the Dawn science team and the public, reveal evidence of Ceres' past subsurface ocean, and indicate that, far from being a dead world, Ceres is surprisingly active," said Carol Raymond, deputy principal investigator of the Dawn mission, based at NASA's Jet Propulsion Laboratory in Pasadena, according to Phys.org. "Geological processes created these bright areas and may still be changing the face of Ceres today."

Most of Ceres' bright spots are no more than a few tens of millions of years old. That is important because it adds to the idea of the dwarf planet's activity. The new findings could shed new light on the distant world and possibly lead to future studies.

"Ceres really isn't a dead world," said lead author Nathan Stein, a planetary scientist at the California Institute of Technology in Pasadena, according to Space.com. "As Dawn continues its mission, we're going to continue to try to characterize and understand in more detail how these bright deposits formed."

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