Two Grand Canyon-size valleys on the far side of the moon formed within 10 minutes, scientists say
Two Grand Canyon-size features on the far side of the moon were likely formed in about 10 minutes after an unknown object ...
NPR11d
The moon's grand canyons were carved in the blink of an eye
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 ten minutes.