Why is Iapetus walnut-shaped?

Read on to find out why Saturn’s moon has such an odd shape

Iapetus' mighty ridge is continually stirring up debate

Iapetus’ mighty ridge is continually stirring up debate

Take a look at Saturn’s third-largest moon Iapetus. The first thing that you’ll probably notice is that the ringed-planet looks like an oversized walnut.

What’s causing it to have this appearance is the mountainous range that wraps around its equator. This ridge is like no other in the Solar System; it rises from the icy surface, reaching up to 12.4 miles high and pans out to be 124 miles wide and it’s thought that this enormous ridge could take up about one-thousandth of Iapetus’ mass. We know a bit about the physical features of this mountainous range but something that experts don’t know, and that’s ever since NASA’s Cassini spacecraft grabbed sight of it in late 2004, is that they are having a difficult time trying to explain how it got there and with that appearance.

Featuring some of the tallest mountains in the entirety of the Solar System, this long equatorial blemish isn’t just complex in its origin, it’s also unusually and heavily cratered, beginning and ending as broken off pieces at random points in its structure. However, despite being quite isolated in places, it also seems to follow Iapetus’ equator almost perfectly.  It’s a puzzle, especially since it prefers to rest only in the moon’s Cassini Regio region.

However, scientists behind Cassini have made some suggestions; did Saturn’s minion become squashed down thanks to rapid rotation in its younger days? Did it once have a ring system during its formation that collapsed onto the moon’s surface, creating the ridge? The theories keep coming, but they have so far been unsuccessful in explaining this confusing moon.

Image Credit: NASA

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