The Grand Canyon in Arizona got carved by water over millions of years of slow but steady erosion. Two similarly-sized canyons on the moon got carved by flying rocks in about 10 minutes. That's because these two canyons formed in the wake of an asteroid or comet smashing into the moon,

The Grand Canyon in Arizona is one of Earth's natural wonders, carved out over millions of years by the gradual erosion power of the Colorado River. Close to the moon's south pole are two canyons each comparable in size to the Grand Canyon that were born in a much different process.

New research shows that when an asteroid slammed into the moon billions of years ago, it carved out a pair of grand canyons on the lunar far side.