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posted by janrinok on Saturday September 03 2016, @11:04PM   Printer-friendly
from the not-so-hot dept.

A liquid ocean under the crust of Ceres, the largest object in the asteroid belt, may have led to the formation of its cryovolcano, Ahuna Mons:

Ahuna Mons is a giant mountain with a[n] icy volcanic dome, a so-called cryovolcano. All volcanic activity for cryovolcanoes happens at low temperatures; they spew icy magma which can consist of freezing water, ammonia or methane instead of hot bubbling lava. The lack of craters on the volcano's surface meant it was probably formed quite recently – a couple of hundred million years at most. Ottaviano Ruesch, lead author of the paper and a NASA scientist working on the Dawn mission, said: "This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and which formed in the geologically recent past."

The possibility of cryovolcanism on Ceres has important implications. Not only does this confirm the dwarf planet's surface temperature of minus 40°C, but it also suggests that its interior has kept warm enough for a sea of salty liquid water to exist below the planet's surface for a relatively long time. "Ceres appears differentiated internally, with a core and a complex crust made of 30 to 40 per cent water ice mixed with silicate rock and salts," said Williams.

The geomorphology of Ceres (DOI: 10.1126/science.aaf4332) (DX)


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  • (Score: 1) by khallow on Sunday September 04 2016, @04:59AM

    by khallow (3766) Subscriber Badge on Sunday September 04 2016, @04:59AM (#397280) Journal

    How can Ceres be -40? Is sunlight at Ceres orbit strong enough to warm Ceres that much?

    Starting with the rough estimate that the Moon has a mean temperature of 0C, Ceres is slightly darker (absorbs 5% more sunlight), heat radiates as the mean temperature to the fourth power, and closest approach (perihelion) to the Sun of 2.5577 AU, I get an estimate of the mean surface temperature of -100 C roughly. But -40C refers to the hottest areas [sciencedirect.com] rather than the mean temperature. On the Moon, the temperature has been measured up to 123C. The same calculation would yield a peak surface temperature of around -32C on Ceres.

    So IMHO yes, that can be done with sunlight alone.