New look at how Earth and moon were created in cosmic explosion
A new model of how the Earth's moon formed is challenging the idea that the early Earth was struck by a Mars-sized body, ejecting material that would become the moon. The new research, by Dr. Robin M. Canup of the Southwest Research Institute, indicates that both bodies in the collision were four to five times the mass of Mars, roughly half the mass of today's Earth.
After colliding once, the two similar-sized bodies re-collided and then merged briefly before separating into an early Earth surrounded by a disk of material that would coalesce into the Moon. The re-collision and merging left the two bodies with the similar chemical compositions seen today. One of the challenges to longstanding theory of the collision is that it likely would have left the Earth and Moon with different chemical compositions.
Watch an animated model of Earth's creation:
The research, funded by NASA’s Lunar Science Institute, Moffett Field, Calif., was published today in the journal Science online.