Nothing is normal on Ceres — least of all its mud volcanoes.In new research published in Nature Astronomy , a large team of astronomers has laid out a new view of the weirdest world in our solar system. It seems that Ceres has had a busy last few billion years — including random smatterings of volcanism, but of a type seen nowhere else in the solar system.Ceres is the largest world in the asteroid belt, and is believed to be a remnant proto-planet, or the kind of small worlds that served as the building blocks of the planets we see today. There’s abundant evidence that Ceres may have once had an ocean that’s since frozen over, and the tantalizing clues to a geologically active history.Ceres even appears to have a form of volcanism. There are two types of volcanism in the solar system, typically: the kinds of magma eruptions seen on Earth and Jupiter’s moon Io, where heated rock wells up from the core to the surface. And then there’s the kind of volcanism seen on Europa and Enceladus, where large plumes of frozen water erupt. Scientists call this cryovolcanism.Hanna Sizemore, a Planetary Science Institute research scientist and author on the paper, says Ceres’ volcanoes are a weird mix of the two. “The big difference on Ceres is that you’re in this hybrid between the inner rocky solar system and the icy outer solar system,” she says. That means that while water may be a driving mechanism for the volcanoes, the actual material could include rock, salt, and heated material from the interior of Ceres, which is both a rocky and an icy world at once. When those volcanoes explode, “It would probably look superficially like lava extrusion on the earth, but it would be mud oozing out of cracks or fissures on the surface,” Sizemore says.Sizemore says a new cryovolcano appears on Ceres roughly once every 50 million years, as indicated by data from the Dawn spacecraft, which has orbited Ceres for around three years. The craft has seen a series of “domes” dotting the world that have similar proportions to mountains, but are made of ices that have since settled after their volcanically active period ended, leveling them out a little.