Los Angeles Times
: Not only is the Moon not made of cheese, but it’s actually composed of the exact same material as Earth, say researchers in a new study
published in Science
. Scientists have long thought that the Moon formed from a collision between Earth and a protoplanet called Theia some 4.5 billion years ago. The authors of the Science
paper say they believe the impact was more than a glancing blow, as had been proposed, and was more likely a head-on crash. They base their finding on the ratio of oxygen isotopes in lunar and terrestrial rocks, which they found to be indistinguishable. That indicates extensive mixing between Earth and Theia, probably due to a “high-energy, high-angular-momentum impact” that allowed everything to melt together.