The two bodies in this portion of an evening-sky view by NASA's Mars rover Curiosity are Earth and Earth's moon. The rover's Mast Camera (Mastcam) imaged them in the twilight sky of Curiosity's 529th Martian day, or sol (Jan. 31, 2014).
This image combines information from three separate exposures taken by Mastcam's right-eye camera, which has a telephoto lens. The body in the upper half of the image is Earth, shining brighter than any star in the Martian night sky. In the lower half of the image is Earth's moon, with its brightness enhanced to aid visibility. To a viewer on Mars, even the moon would appear as bright as a very bright star.
The distance between Earth and Mars when Curiosity took the photo was about 99 million miles (160 million kilometers).
NASA spacecraft that have previously returned images of Earth taken from Mars orbit or from the surface of Mars include Mars Global Surveyor in 2003 (PIA04531), Mars Exploration Rover Spirit in 2004 (PIA05560) and Mars Reconnaissance Orbiter in 2007 (PIA10244).
NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington. JPL designed and built the project's Curiosity rover. Malin Space Science Systems, San Diego, built and operates the rover's Mastcam.
More information about Curiosity is online at http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/.