Theia in context with moon

Theia is the name of a Mars-size protoplanet which is said to have impacted earth giving rise to moon. The name is derived from the mythical Greek titan Theia, who gave birth to the Moon goddess Selene. This designation was first proposed by the English geochemist Alex N. Halliday in 2000 and has since become accepted in the scientific community.

According to modern theories of planet formation, Theia was part of a population of Mars-sized bodies that existed in the Solar System 4.5 billion years ago. Indeed, one of the attractive features of the giant impact hypothesis is that the formation of the Moon fits into the context of the formation of the Earth itself: during the course of its formation, the Earth is thought to have experienced dozens of collisions with such planet-sized bodies. The Moon-forming collision was only one such "giant impact" and perhaps the last.

Why Theia was in news recently?

Theia was recently in news because now the researchers have cast doubts over Moon’s origin, challenging the widely held theory that a giant collision between Earth and a Mars-sized object — that scientists call Theia — gave birth to the moon 4.5 billion years ago. There was an analysis study of titanium from the Moon, Earth and meteorites, published by Junjun Zhang at the University of Chicago, and four co-authors. This analysis indicates the Moon’s material came from Earth alone and not mars.