Caption: 
This simulation of a giant impact with the Earth shows an off-center, low-velocity collision of two protoplanets. Color scales indicate particle temperature in Kelvin, with blue-to-red indicating temperatures from 2,000 K to in excess of 6,440 K. After the initial impact, part of the impactor re-collides with the Earth, while other material is placed into a vapor-melt disk orbiting the Earth. 