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. Those analyses, reported in the Dec. 11 Science, suggest that those gases, as well as many others now cloaking our planet, arrived via comets or were swept up from nearby gas clouds during the late stages of Earth’s formation.


Earth’s Atmosphere May Have Alien Origin | Wired Science | Wired.com