Making the Moon

(Image courtesy NBC News)

The hard science stuff is further down in this NBC News report, but the revised theory on how our Moon was formed is fascinating all on its own:

The formation of the moon has long remained a mystery, but new studies support the theory that the moon was formed from debris left from a collision between the newborn Earth and a Mars-size rock, with a veneer of meteorites coating both afterward.

Earth was born about 4.5 billion years ago, and scientists think the moon arose a short time later. The leading explanation for the moon’s origin, known as the Giant Impact Hypothesis, was first proposed in the 1970s. It suggests the moon resulted from the collision of two protoplanets, or embryonic worlds. One of those was the just-forming Earth, and the other was a Mars-size object called Theia. The moon then coalesced from the debris.

I want to know what happened to Theia, and is there even the slightest chance of it making a return visit?