Oppurtunity and Spirit are two semi-autonomous rovers that are currently surveying the Martian landscape. Built by NASA, Opportunity is the second of the two rovers of NASA's Mars Exploration Rover Mission. She landed successfully on Mars on January 24, 2004.
In addition to enormously valuable scientific work, both the rovers have also wowed us with lovely pictures (Spirit here, Oppurtunity here) from the red planet:). The latest image from Oppurtunity is a particularly poignant one, as the rover looks up in the sky, and finds its home planet, the planet it will never again be able to visit.

Hello Earth! (Courtesy: Mars Exploration Rover Mission)On its 449th martian day, or sol (April 29, 2005), NASA's Mars rover Opportunity woke up approximately an hour after sunset and took this picture of the fading twilight as the stars began to come out. Set against the fading red glow of the sky, the pale dot near the center of the picture is not a star, but a planet - Earth:):).
Earth appears elongated because it moved slightly during the 15-second exposures. The faintly blue light from the Earth combines with the reddish sky glow to give the pale white appearance.
I wonder when it will be us humans who will be able to take such pictures of Earth, from the surface of Mars.