NPR
Around 20,000 years ago, Earth was very, very cold. Global temperatures were 10 degrees Fahrenheit colder than they are today and most of North America was covered in ice. That ice was almost half a mile high in some areas. But how did Earth get out of this ice age?
It's a question scientists got a lot closer to answering recently. A study published in the journal Science found clues about this ancient ice thanks to a brand new method: analyzing the amounts of cosmic dust in ancient arctic ocean soil. The dust is microscopic asteroid and comet debris that constantly rains in space, eventually making its way to Earth.
Before the study began, University of Washington geochemist Frankie Pavia wasn't sure it would work. So, he says he ran the idea by his main collaborator, Jesse Fa