Dendrochronology is the science of calculating a tree's age by its rings.
Tree rings provide precise information about environmental events, including volcanic eruptions.
A mature birch tree can produce up to 1 million seeds per year.
Moon trees were grown from seeds taken to the moon by Stuart Roosa, Command Module pilot of the Apollo 14 mission of January 31, 1971. The effort included 400-500 seeds, which orbited the moon on the first few days of February 1971. NASA and the USFS wanted to see if being in space and in the moon's orbit would cause the seeds to grow differently than other seeds.