Earth’s deep interior may hold water equal to today’s oceans, challenging long-held views of how the planet became habitable.

This superionic state of matter would neatly explain some unusual behavior in the core, such as the way it slows certain waves, and measurements that suggest it's squishy like butter rather than rigid ...

Our Earth is structured sort of like an onion – it’s one layer after another. Starting from the top down, there’s the crust, which includes the surface you walk on; then farther down, the mantle, ...