The rocky ranges of Iapetus (Discover Magazine)

Carl Engelking writes on Discover‘s D-Brief blog:

It may sound like something out of “Chicken Little,” but at some point in the history of Saturn’s moon Iapetus, the sky was actually falling: Scientists reported this week that an entire 800-mile-long mountain range along the moon’s equator formed after it fell from space.

He continues:

The researchers’ hypothesis hinges on the observation that most peaks in the Iapetus range are steep, triangular peaks near their “angle of repose,” or the maximum angle objects, like rocks, can rest on a slope without falling down. If the mountain range were created through volcanism or tectonic forces, the shapes of the peaks would be more shallow and varied.

Therefore, researchers claim their findings support the hypothesis of an “exogenic” — from outside the moon — origin of the Iapetus range.

Read the rest here.