The spherules were created when asteroids crashed into Earth, vaporizing rock that expanded as a giant vapor plume. Small droplets of molten rock in the plume condensed and solidified, falling ...

This article was originally published with the title “ Cosmic Spherules and Meteoritic Dust ” in Scientific American Magazine Vol. 202 No. 2 (February 1960), p. 123 doi:10.1038 ...