m. c. de marco: To invent new life and new civilizations...

The Search for Theia

Science@NASA reports on the search of L4 and L5 for remnants of the hypothetical proto-planet Theia which may have crashed into Earth to form the Moon:

Debris from the collision, a mixture of material from both bodies, spun out into Earth orbit and coalesced into the Moon. This scenario explains many aspects of lunar geology including the size of the Moon’s core and the density and isotopic composition of moon rocks.

It’s a good theory, but it leaves one awkward question unanswered: Where did the enormous protoplanet come from?

Belbruno and Gott believe it came from a Sun-Earth Lagrange point.