The red planet
The fourth planet from the sun, Mars is one of our closest neighbors yet it remains a mystery. There is strong evidence that water once flowed on the planet, but what happened to make it disappear? Is there life there? So many questions, and our quest to learn more about the red planet is just beginning. As NASA's Mars rovers continues to feed our curiosity about the red planet, we can admire it from afar.
This gallery has been updated with new information since it was originally published October 2010.