Mars is weird. It's small, and cold, and has a thin atmosphere that's almost entirely carbon dioxide, and what isn't CO2 is nitrogen and, bizarrely, argon. So you expect to see weird landscapes. But even so, Mars has the potential to be really, really weird. Check this out:
That slightly disturbing image (click to embiggen) is not a microscopic picture of a scientist's colon (at least, not as far as you know). It's actually a region near the Martian south pole. It was taken with the HiRISE camera on the Mars Reconnaissance Orbiter, and the area shown is roughly 700 meters across (about 0.4 miles). What you're seeing are layers of the polar ice cap. The ice is mostly CO2. Mars is so cold that a lot of the cap persists throughout the year, and is called the residual cap. Some of it does sublimate, though, which means it goes ...
