Iapetus

Source: NASA

Two-toned, ying-yang, oreo, whatever helps you remember: this is IAPETUS.  The moon with two personalities.

Reigning in as Saturn’s 3rd largest moon, its average radius is 457 miles.  Its composition is 1/3 rock, 2/3 ice.  Now onto its surface…holy crap.  Mostly, Iapetus’ surface composition is a mysterious reddish material (commonly linked to the same mysterious red-stuff on Europa).  There are some theories out there explaining why this satellite has the face it does, and I’m gonna go over a few of ‘em.  Distance?  Iapetus is roughly 2.2 million miles away from Saturn, meaning two things: the gravitational tug of the giant planet doesn’t really rock Iapetus’ world enough to resurface it + this satellite has a KILLER view of Saturn’s trademark rings.  So whatever went down in the past, the moon never got the chance (like some other moons) to recover it- so we see all of its battle scars, etc.  Another theory is that Iapetus is a dust pan.  Catch that?  A dark nearby moon, Phoebe, could possibly be feeding the dark side of Iapetus, as it sweeps up the particles.  Theory number three is that there could be ice volcanoes depositing dark material onto the exterior.  Lastly, what is more favored in the science community (+ rooted on by Cassini), is that Iapetus suffers from *thermal segregation*, which is basically exactly what it sounds like.  This moon in ominous looking, and the half-n-half-ness of it is so distracting yet still beautiful.  But buckle up, there’s still more!!  Iapetus has an “equatorial ridge” which is a 6-mile chain of mountains running along the equator.  Just like the mysterious material shrouding ½ of the surface, there are theories surrounding the equatorial ridge, as well.  My favorite? An ancient collapsed ring.  It astonishes my socks off to know that this moon has existed for so long and been through so much.  It astonishes me that it even exists.  I wander through the solar system, just like how I am taking you through it, and am shocked to find moons like this one.  Products of their environment, the opportunities are endless.