Vesta is the second-largest asteroid in the Solar System, and recent measurements by the Dawn mission showed that it’s actually a protoplanet: a piece of planet-like material left over from the early days of our Solar System. However, Dawn is significantly non-spherical and very battered. Most notably, it has two huge overlapping craters near its south pole, marking impacts that nearly shattered the asteroid, and which raised a mountain higher than any other in the Solar System. Now, a computer simulation may have showed how Vesta came to be the fascinating, scarred, wonderful object we see today.

As with other Solar System bodies, Vesta bears the scars of its history. The most substantial of these scars are the two large impact basins, Veneneia and Rheasilvia. (Both craters were named for virgins who served the goddess Vesta in Roman mythology—the vestals.) Rheasilvia formed about 1 billion years ago and is larger. Veneneia is smaller and formed at least 2 billion years ago; its presence was partly obscured by the later impact. Meteorites from Vesta, possibly ejected by the impacts forming Rheasilvia and Veneneia, have been found on Earth. [Read more….]