A northern portion of the rim of Endeavour Crater is visible on the horizon of this image taken by the panoramic camera (Pancam) on NASA's Mars Exploration Rover Opportunity on March 7, 2009, during the 1,820st Martian day, or sol, of the rover's mission on Mars.
That portion of Endeavour's rim is about 20 kilometers (12 miles) away from Opportunity's position west of the crater when the image was taken. The width of the image covers approximately one degree of the horizon.