Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more . CNN  —  About 3.8 billion years ago, two massive canyons likely formed on the moon in a span of less than 10 minutes, according to new research. The extraordinary formations, each comparable in size to Earth’s Grand Canyon, are hidden on the far side of the moon — the side that always faces away from Earth — near the lunar south pole, where NASA’s