The discovery of superionic ice potentially solves the puzzle of what giant icy planets like Uranus and Neptune are made of. Theyâ€™re now thought to have gaseous, mixed-chemical outer shells, a liquid layer of ionized water below that, a solid layer of superionic ice comprising the bulk of their interiors, and rocky centers.
The findings, published today in Nature, confirm the existence of â€œsuperionic ice,â€ a new phase of water with bizarre properties. Unlike the familiar ice found in your freezer or at the north pole, superionic ice is black and hot. A cube of it would weigh four times as much as a normal one. It was first theoretically predicted more than 30 years ago, and although it has never been seen until now, scientists think it might be among the most abundant forms of water in the universe.
Across the solar system, at least, more water probably exists as superionic ice â€” filling the interiors of Uranus and Neptune â€” than in any other phase, including the liquid form sloshing in oceans on Earth, Europa and Enceladus. The discovery of superionic ice potentially solves decades-old puzzles about the composition of these â€œice giantâ€ worlds.