The asteroid Vesta could be a huge chunk of planet that was blasted off its parent world and sent spinning into space in the aftermath of a titanic collision four-and-a-half billion years ago.
That's the conclusion of researchers who have carefully mapped Vesta's gravity field and the way that the asteroid moves through space. If they're right, it puts to rest to the idea that Vesta itself is actually a stalled protoplanet. During the birth of the solar system, the planets are thought to have formed and grown through a process known as core accretion, building themselves up by sweeping up rocky debris and adding mass through collisions with other protoplanets.
