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Dwarf planet Ceres’ bright spots indicate an ancient ocean

A view of the bright spots of the dwaf planet Ceres’ Occator Crater. Cerealia Facula is in the center, while the Vinalia Faculae is to the right.

(NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

NEW ORLEANS — The dwarf planet Ceres’ famous bright spots to suggest that the grey, crater-laden world is surprisingly active, a new study reports.

Ceres’ bright spot can overlie pools of salt water, which are the remnants of an ancient underground ocean, study team members said.

“It is possible that there is still salt come to the surface,” lead author Nathan Stein, a planetary scientist at the California Institute of Technology in Pasadena, told Space.com. “It is certainly intriguing.” [Awesome Ceres Photos by NASA’s Dawn Spacecraft]

Stein and his team classified in the more than 300 bright spots on Ceres’ surface in four groups, while planetary geologist Lynnae Quick, of the Smithsonian Institution in Washington, D. C., examined what would be the control of the places differ. Along with Carol Raymond, the deputy principal investigator for NASA’s Dawn mission, which already has an orbit Ceres in March 2015, the pair presented their results here at the American Geophysical Union meeting on Tuesday (Dec. 12).

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Ceres’ shiny spots

As the Dawn approached Ceres in the spring of 2015, the spacecraft saw a handful of bright flashes of light on the dwarf planet’s surface. Further research brought a wealth of places made of salts stretches across the planet, almost all of which are in or around the craters. Variations in the spots’ appearance have helped scientists better understand how they are formed.

Stein found that the most reflective material on Ceres has a tendency to lie at the bottom of craters. Some of the first identified spots sit on the floor of 57 km wide (92 km) Occator Crater, which hosts two prominent bright areas, Cerealia Facula in the center and the Vinalia Faculae to the east. Cerealia Faculae is a collection of the brightest material on Ceres, spread over a 6-mile-wide (10 km) pit with a small dome in the middle. Vinalia Faculae is weaker and slightly less reflective.

Another type of Ceres bright material perches on the edges of craters, streaks down. More than the material on the floor, this was probably exposed by the objects that crashed into Ceres. The third class of material, spread over the edges of craters, was probably ejected by impactors, the researchers determined.

The “lonely mountain” Ahuna Mountains, with bright spots on the flanks, is in a class of its own. The only major peak on Ceres, it has no clear connection to a crater. Instead, scientists think that Ahuna Mons is the most likely to be a cryovolcano, created by the accumulation of flowing ice.

Freshly exposed material is clear, but in the course of millions of years, the spots slowly mixing with the dark material that covers the surface of Ceres. In the past, thousands of light shiny spots may have spotted the dwarf planet, the researchers said. [What Would It Be like to Live on Ceres?]

The new study appears in the journal Icarus.

Shocked Ceres soda

The source of the bright spots was a question that plagued Quickly. Although the stains could have formed by different means, the team members believe that they are likely to arise out of the pockets of brine under the surface — the remains of a liquid layer in the past.

“We believe that these bright spots are a sign that Ceres once had a global ocean,” Quick said. In fact, they suggested that the activity on the dwarf planet may also be occurring on a larger scale on the icy moons of the outer solar system, Jupiter’s moon Europa and the Saturn satellite Enceladus.

If this interpretation is correct, Ceres’ ocean slowly froze from the course of time, leaving behind what Stein called “discrete pockets of brine.” Scientists suspect that these are isolated pools rather than a full liquid layer, because the light spots themselves are discontinuous, he explained. “Not every new crater expose [brine],” Stein said.

As the salty liquid cooled and began to freeze, the expanding ice pushed the liquid, Quickly said. In many cases, the brine would have been pushed to the surface by means of a network of fractures. Another option is that impactors “squeezed and pinched” these bags, ” she said, creating pressure that pushed material up to the top.

The things become even more interesting when the salty liquid comes out from the ground, on Ceres’ airless surface.

“As brine to the surface, but they are and go to the fountain, or the cook,” Quick said. She compared the process to a shaken soda can after it is opened. Such spit soda is caused by the interaction of gases that cause the liquid to expand or fountain up and out.

“We believe that when brine to the surface on Ceres, that is what happens,” she said.

When the material is thin, it can spit out in an arc, splashing icy particles around the surface. This could explain some of the diffuse groups of spots, Quickly said.

Thicker, icy lava may have used the superbright Cerealia Facula, the researchers said. If the material is seeped in through the cracks to the surface, it probably formed a dome. The outer layers froze into an icy shield that is insulated from the cold lava below. New beautiful spots formed on the surface of cracks or fractures permitted material fountain to the outside.

Ahuna Mons probably took this process to the utmost, the pile up icy lava on top of itself to create its high altitudes. Depressions in the surface are allowed material to cooking, making the icy spots are visible on the mountain’s flanks today.

According to Stein, the majority of Ceres’ bright spots are young, not more than a few tens of millions of years old. (Keep in mind that the solar system itself is a whopping 4.5 billion years old.) That could mean that Ceres is still active today, ” he said.

“Ceres is really not a dead world,” Stein said. “If the Dawn continues her mission, we are going to continue to try to characterize and to understand in more detail how these bright deposits are formed.”

Originally published on Space.com.

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