Of the 12 astronauts who have ever walked on the moon, all did so wearing the same exact watch, a NASA-issued Omega Speedmaster.
But on the Apollo 15 mission in 1971, Commander David Scott's watch broke during his second day of traversing the lunar surface. So on his third and final day on the moon, Scott wore his own watch that he brought along as a backup.
Since then, there has been speculation about what kind of watch Scott wore, and what happened to it. Now, some 40 years later, the mystery is solved, and collectors can bid on this one-of-a-kind space artifact at an upcoming auction.