But once Gondwana took up its polar position in the late Ordovician, massive glaciers formed over Africa at the supercontinent's center. This heralded a 20-million-year ice age during which ...

A new study, based on a census of stars in the Milky Way, indicates that these ice ages might have been triggered by nearby ...

Two of Earth’s five confirmed mass extinction events could have been caused by nearby supernova explosions stripping the ...