Crystals Brought Back By Astronauts Show That Moon Is 40 Million Years Older Than Scientists Thought

More than 4 billion years ago, when the Solar System was still young and the Earth was still growing, a giant object the size of Mars crashed into the Earth. The biggest piece that broke off of the early Earth formed our Moon. But precisely when this happened has remained a mystery.

In a new study in the journal Geochemical...