Ceres’ lonely ice volcano is only one of many

The dwarf planet Ceres has had as many as 22 ice volcanoes, new research suggests.

Images from NASA’s Dawn mission has revealed there is currently a single volcano, an icy peak known as Ahuna Mons.

But research based on data from the mission suggests that new volcanoes have appeared around every 50 million years over the past billion. They erupt, build up and then sink back into the surface.

The research, published in Nature Astronomy, suggests that Ahuna Mons is relatively young.

“Ahuna Mons has an upper age limit of 240 million years derived from crater size,” the researchers, led by University of Arizona planetary scientists Michael Sori, write. “But it may be much younger because the mountain itself is too small and has too few craters to be reliably dated.”

Ice volcanoes, or cryovolcanoes, leave less impact on the surface than volcanoes on planets such as Earth. 

Instead of molten rock, they erupt liquid or gaseous ammonia, water or methane. 

Traces of cryovolcanism have been found on several bodies in the outer Solar System. “Cryovolcanism may be an important planetary phenomenon in shaping the surfaces of many worlds in the outer Solar System and revealing their thermal histories,” the researchers say.

“However, the physics, chemistry and ubiquity of this geologic process remain poorly understood, especially in comparison to the better-studied silicate volcanism on the terrestrial planets.”

NASA’s Dawn spacecraft discovered Ahuna Mons while orbiting Ceres in 2015. 

Sori and colleagues used models of relaxing dome shapes to identify 22 former cryovolcanoes on Ceres in images taken by the Dawn mission. 

The authors also estimate that the total amount of icy material that has been erupted onto the surface of Ceres is one hundred to one hundred-thousand times less than the volumes of molten rock erupted on the Earth, Moon, Venus or Mars.

Ceres was the first object discovered in the main asteroid belt when Italian astronomer Father Giuseppe Piazzi spotted the object in 1801. It was initially classified as a planet but later classified as an asteroid as more objects were found in the same region.

In recognition of its planet-like qualities, Ceres was designated a dwarf planet in 2006 along with Pluto and Eris.