Earth’s atmosphere may be extraterrestrial in origin

Isotopic analyses of the gases krypton and xenon suggest that much of Earth’s atmosphere came from outer space, not inner space.

Krypton and xenon appear in Earth’s atmosphere — and in the universe as a whole — only in trace amounts. Detailed analyses of the gases provide clues about where those atmospheric components originated, says Greg Holland, an isotope geochemist at the University of Manchester in England.