Clouds scoot across the Martian sky in a movie clip consisting of 10 frames taken by the Surface Stereo Imager on NASA's Phoenix Mars Lander. This clip accelerates the motion. The camera took these 10 frames over a 10-minute period. Particles of water-ice make up these clouds, like ice-crystal cirrus clouds on Earth. Credit: NASA/JPL- Caltech/University of Arizona/Texas A&M University
