Beautiful pictures of Mars from Nasa 4

On Mars the seasonal polar caps are composed principally of frozen carbon dioxide. In the springtime as the sun shines on the ice, it turns from solid directly to gas. From Earth, the expansion and contraction of the Martian polar caps are readily visible.

Read more: http://science.time.com/2012/08/06/martian-vistas-a-look-at-curiosity-rovers-new-home/#ixzz2HGvZsYjY