Spewing water, ammonia and methane rather than molten rock, ice volcanoes are among the strangest geological phenomena in our solar system.
Well, they just took a turn for the even more bizarre.
The discovery of a single ice volcano (cryovolcano) on Ceres, a dwarf planet orbiting between Mars and Jupiter, baffled astronomers.
While icy worlds in the more distant solar system each boast several cryovolcanoes, Ceres’s 2.5 mile high Ahuna Mons stood alone.
“Imagine if there was just one volcano on all of Earth,” said Michael Sori, lead of author of a new paper investigating the phenomenon. “That would be puzzling.”
The explanation? Ice volcanoes can vanish.
“We think we have a very good case that there have been lots of cryovolcanoes on Ceres but they have deformed,” added Sori, who’s an astronomer at the University of Arizona.
The study suggests that over millions of years, other cryovolcanoes have flattened or become indistinguishable from the planet’s surface.
The processes that cause volcanoes on Earth to deteriorate – wind, rain and ice – don’t exist on Ceres because the world doesn’t have an atmosphere.
Instead, Ceres’ ancient volcanoes have flattened as a result of a process known as viscous relaxation – the tendency for every solid to flow if it has enough time.
On Earth, it causes glaciers to move, and on Ceres it’s suspected to have caused older ice volcanoes to flatten out until they vanished.
“Ahuna Mons is at most 200 million years old. It just hasn’t had time to deform,” Sori said.
Kelsi Singer, a researcher of icy worlds at Southwest Research Institute in Colarodo who wasn’t involved with the study, said it would be interesting to see if older domes on Ceres fit the theory.
“Because all of the putative cryovolcanic features on other worlds are different, I think this helps to expand our inventory of what is possible,” Singer added.