New research has revealed that the surface of Uranus’ moon Ariel is coated with a significant amount of carbon dioxide ice, particularly on its trailing hemisphere, which always faces away from the moon’s direction of orbital motion.
The icy dwarf planets Eris and Makemake have surfaces bearing methane ice of unknown origin. The two planets may have warm oceans.
Saturn's small, crater-covered moon Mimas may have a vast ocean under its thick icy surface, according to a new paper.
Scientists now believe Miranda and Ariel, the smallest and second-smallest of Uranus’s five major moons, could be expelling vapour plumes - which on other moons in the solar system are thought to come from subsurface oceans.