Synestias give new insights into how planets and moons form. This figure shows to scale a rocky planet, a molten disk/ring structure, and a synestia all with the same mass (about one Earth mass). | Simon Lock, Harvard University

Earth May Once Have Been a Donut-Shaped Mass of Vaporized Rock Called a Synestia

Research posits that Earth emerged from a completely new structure after a planetary collision, with outer layers of vaporized rock rotating in orbit around the rest of the body.