There's Nobody Left On Mars

Like all the planets in our solar system, Earth and Mars orbit the sun. But Earth is closer to the sun, and therefore races along its orbit more quickly. Earth makes two trips around the sun in about the same amount of time that Mars takes to make one trip. So sometimes the two planets are on opposite sides of the sun, very far apart, and other times, Earth catches up with its neighbor and passes relatively close to it. (...)
http://mars.nasa.gov/allaboutmars/nightsky/nightsky03/

http://mars.nasa.gov/multimedia/interactives/billionpixel/?image=PIA16918&view=pano
http://mars.nasa.gov/allaboutmars/nightsky/