About 466 million years ago, long before the age of the dinosaurs, the Earth froze. The seas began to ice over at the Earth’s poles, and the new range of temperatures around the planet set the stage for a boom of new species. The cause of this ice age was a mystery, until now: a new study by a group of scientists including a University of Chicago professor argues that the ice age was caused by global cooling, triggered by extra dust in the atmosphere from a giant asteroid collision in outer space.
There’s always a lot of dust from outer space floating down to Earth, little bits of asteroids and comets, but this dust is normally only a tiny fraction of the other dust in our atmosphere, such as volcanic ash, dust from deserts and sea salt. But when a 93-mile-wide asteroid between Mars and Jupiter broke apart 466 million years ago, it created way more dust than usual.
“Normally, Earth gains about 40,000 tons of extraterrestrial material every year,” said Philipp Heck, associate professor of geophysical sciences at the University of Chicago, a curator at the Field Museum and one of the paper’s authors. “Imagine multiplying that by a factor of a thousand or ten thousand.”
To contextualize that, in a typical year, one thousand semi trucks’ worth of interplanetary dust fall to Earth. In the couple million years following the collision, it’d be more like ten million semis.