ST. LOUIS (KMOX) - Where in the world did the moon come from? Washington University researchers say they have strong evidence it was the result of celestial fender-bender.

The moon was born out of a giant collision between a body the size of Mars and the Earth. That’s the conclusion drawn by Washington University researchers, led by Frederick Moynier, who says he has the first physical evidence supporting the so-called giant impact theory, thanks to the chemical analysis of 20 moon rocks brought back to Earth by the Apollo missions.

“We got the moon rocks and we’ve been able to do that kind of study which is the kind of think you cannot do just using telescopes.”

Moynier says that when a large vaporized rock condensed after colliding with Earth, it became the moon.