The key piece of evidence that convinced scientists that some meteorites could have come from the Moon was the identical isotopic composition of these meteorites and lunar samples brought back by Apollo missions.

Here's why this was so significant:

* Isotopes are atoms of the same element with different numbers of neutrons. This means they have the same chemical properties but slightly different atomic masses.

* The isotopic composition of an object is like its unique fingerprint. It reflects the specific conditions under which it formed and evolved.

* Lunar samples brought back by Apollo missions had a unique isotopic signature. Scientists meticulously analyzed these samples and discovered their distinctive isotopic ratios.

* When meteorites were found with the exact same isotopic composition as the lunar samples, it became compelling evidence that these meteorites originated from the Moon.

This discovery was a major breakthrough in our understanding of the Moon and the early Solar System. It provided strong evidence that impacts on the Moon could launch material into space, leading to the possibility of lunar meteorites reaching Earth.