List of retroreflectors on the Moon

Retroreflectors are devices which reflect light back to its source. Seven retroreflectors were left at seven sites on the Moon by three crews of the Apollo program, two by remote landers of the Lunokhod program, one by the Commercial Lunar Payload Services program and one by the Chandrayaan program.

Source: Wikipedia — List of retroreflectors on the Moon (CC BY-SA 4.0)