Moon material on Earth

Material blasted off the moon’s surface by the impact of giant meteorites has dropped upon the earth on at least three separate occasions in the geological past. Strange glassy objects — called “tektites” and “impactites” — are found by the thousands in sites scattered across the earth. One theory is that tektites are solidified droplets of lunar material melted and splashed into space when large meteorites crashed into the moon. Impactites are thought to be products of the impact of large extraterrestrial objects against the earth. Evidence linking the formation of tektites and impactites was provided by a new technique for dating geological specimens.

UPDATE

Moon rocks collected by the Apollo missions put holes in the theory that tektites were of lunar origin; the two were just too different. Scientists now think that tektites are a type of impactite, formed during the rapid heating and cooling of material ejected when a meteorite strikes Earth.