Study Traces Moon-Forming Impact to an Inner Solar System Neighbour Named Theia
A new isotopic study reveals that Theia—the Mars-sized body that struck Earth 4.5 billion years ago to form the Moon—likely originated in the inner Solar System, close to Earth’s birthplace. By comparing heavy-element isotope ratios in lunar rocks, Earth samples, and meteorites, researchers found identical signatures, showing both worlds formed from the same inner-disk material. Mass-balance models confirm Theia and Earth grew as near neighbors before their catastrophic collision.
