Moon's Origin Remains a Puzzle as Scientists Revisit Theia Scenario

Scientists still don’t fully know how the Moon formed after a giant impact with Theia about 4.51 billion years ago; estimates of Theia’s size range from Mercury-sized to roughly half Earth’s mass, and while newer hydrodynamic models that favor a larger impact can explain why Moon rocks resemble Earth's chemically, Apollo samples like the Genesis Rock complicate the picture. Researchers also study lunar magma ocean conditions in the lab to probe mineral formation, but the exact origin remains unresolved.