Ancient Comets May Have Delivered Xenon To Earth

Comets hurtling through space 3.5–4.5 billion years ago may have deposited heavy isotopes of xenon into Earth’s atmosphere. This clue to the isotopes’ mysterious origins suggests that comets visited Earth in its earliest days, that the moon and atmosphere are younger than we originally thought, and that comets might have delivered the first organic material to our fledgeling planet.

While there are only trace amounts of xenon in the atmosphere, the noble gas doesn’t chemically react with other elements.. Read more.