Cosmic Dust Supports a Snowball Earth

摘要

Answering questions about Earth's climate of more than half a billion years ago can be a challenge—even questions as stark as whether land and sea were completely coated by ice from pole to pole. Indeed, the revival of the Snowball Earth hypothesis almost 7 years ago has bogged down of late, as paleoclima-tologists have failed to turn up unequivocal evidence that ice enrobed our planet.