Clouds appear in the martian sky above "Endurance Crater" in this mosaic of frames taken by the navigation camera on NASA's Mars Exploration Rover Opportunity during the morning of the rover's 291st sol (Nov. 17, 2004). The view spans an arc from the east on the left to the southwest on the right.

Opportunity has observed differences in cloudiness from one sol to the next, a reminder that Mars, like Earth, has daily weather as well as longer-term seasonal changes.

The images that are combined to produce this view have been processed to remove geometrical distortion associated with the camera's 45-degree field of view. In addition, special image processing has been applied to the original images to enhance the clouds and make them visible across the entire mosaic. Glare from the Sun washed out the clouds on the left in the original images; this glare was removed. The left-most image in this mosaic contains some artifacts from pointing the camera toward the Sun. The rim of Endurance has been processed separately and merged back with the sky to better show the context.