Up until 1963, both the U.S. and Soviet governments conducted over 500 atmospheric nuclear weapons tests. They blew up these weapons anywhere from 16 miles above Earth to 250, well into space. The resulting fallout is estimated to have raised levels of thyroid cancer across the country, and could one day even serve as a marker for the Anthropocene—the age of humans.

But the effects of these tests spread far beyond the surface of the Earth. A nuclear explosion creates a storm of charged pa