Water has played a big role in shaping dwarf planet Ceres

Ahuna Mons on Ceres

The 4-kilometer-high mountain Ahuna Mons on the dwarf planet Ceres is probably a cryovolcano, new findings suggest. This photo was assembled from images taken by the Dawn spacecraft.

JPL-Caltech/NASA, UCLA, MPS, DLR, IDA

Ice volcanoes, patches of water ice and a slew of hydrated minerals on Ceres paint a picture of the dwarf planet as a geologically active world — one where water has played a starring role. That’s the theme of recent findings by the Dawn spacecraft, described in six papers in the September 2 Science.

A 4-kilometer-high mountain dubbed Ahuna Mons, with its bowl-shaped summit and ridged flanks, has the appearance of a cryovolcano — one that erupts water instead of magma. The relatively young Oxo crater also appears to be home to splotches of frozen water. Given that ice should last only tens of years on the surface of Ceres, the patches must be very recent additions, possibly exposed by a landslide or impact with a meteorite. And the surface of Ceres is slathered with a class of minerals known as phyllosilicates — silicon-bearing substances that form in the presence of water — which further support the idea that water has been present throughout Ceres’ history.

Ceres is the largest body between Mars and Jupiter. Dawn has been orbiting Ceres since March 6, 2015, studying its geology and composition to better understand the formation of rocky worlds. The spacecraft will become a permanent satellite of Ceres after its mission ends in early 2017.

Christopher Crockett is a freelance science writer and editor based in Arlington, Va. He has a Ph.D. in astronomy from the University of California, Los Angeles.

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