Ceres' bright spots suggest the dwarf planet is geologically active

"Previous research has shown that the bright material is made of salts, and we think subsurface fluid activity transported it to the surface to form some of the bright spots," said Caltech researcher Nathan Stein.

By Brooks Hays

Dec. 13 (UPI) -- New observations and analysis of the hundreds of bright pots on Ceres surface suggest the dwarf planet is a dynamic, geologically active place.

Scientists have struggled to account for the highly reflective spots on Ceres' surface, but thanks to images captured by NASA's Dawn spacecraft, revealing the bright spots in unparalleled detail, researchers are beginning to understand how the features formed and changed over time.


"Geological processes created these bright areas and may still be changing the face of Ceres today," NASA researcher Carol Raymond said in a news release.

Along with her colleagues at NASA's Jet Propulsion Laboratory, Raymond, deputy principal investigator on the Dawn mission, relayed the newest insights into the nature of Ceres' bright spots at the American Geophysical Union meeting in New Orleans this week.

With the help of Dawn's cameras, scientists have identified more than 300 bright spots. One group of bright spots features reflective material in the center of craters, on the crater floor. The brightest examples, Vinalia Faculae and Cerealia Facula, are both found in the Occator Crater.

The Cerealia Facula bright spot, the brightest on Ceres, features reflective material covering a six-mile-wide expanse. A salt-rich material is responsible for the reflectivity.


Another type of bright spot, the most common, features reflective material along the rims of craters. Scientists believe these bright streaks were created when impacts exposed reflective materials beneath the surface.

Another bright spot is caused by Ahuna Mons. Researchers believe the mountain is cryovolcano formed by accumulating flows of icy materials. The volcano features bright streaks along its slopes.

"Previous research has shown that the bright material is made of salts, and we think subsurface fluid activity transported it to the surface to form some of the bright spots," said Nathan Stein, a doctoral researcher at Caltech.

Back inside the Occator Crater, scientists believe different geologic processes account for the two bright spots. The reflectivity of Vinalia Faculae is diffused. Researchers believe a salty fluid from an underlying reservoir was expelled through fissures by a volatile gas. As the briny discharge boiled away, salt particles were left behind, staining the surface with a reflective sheen.

Cerealia Facula, which is brighter and higher in elevation, formed different, scientists hypothesize. Here scientists believe an icy lava created a dome-like shape while also delivering similarly salty fluids to the surface. As the fluids evaporated, reflective salt particles were left behind, forming the bright spot.


While the impact that created Occator is directly responsible for these geologic mechanisms, the collision may have enhanced the fissures that allowed for the briny reservoir to access the surface.

"We also see fractures on other solar system bodies, such as Jupiter's icy moon Europa," said Lynnae Quick, a planetary geologist at the Smithsonian Institution. "The fractures on Europa are more widespread than the fractures we see at Occator. However, processes related to liquid reservoirs that might exist beneath Europa's cracks today could be used as a comparison for what may have happened at Occator in the past."

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