Wired‘s Space Photo of the Day:
This spectacular erosion the surface of the red planet happens when seasonal polar ice caps made from dry ice (CO2) get vaporized by the spring sun, turning it straight from solid to gas. This makes weird spider-like formations across the terrain.
In this picture you can see the bright ice nestled in the eroded channels. In warmer seasons the ice will disappear into the atmosphere and only the spiders will be left.This is a Martian specialty – Earth is just too hot to make it happen. Read more here.