This movie clip shows dust devils moving across the plain inside Mars' Gusev Crater, as seen with a hazard-identification camera on NASA's Mars Exploration Rover Spirit. The clip consists of consists of frames taken by that camera during a span of 8 minutes, 26 seconds on the rover's 559th martian day, or sol (July 29, 2005). Contrast has been enhanced for anything in the images that changes from frame to frame, that is, for the dust moved by wind.
Spirit began seeing dust devil activity around the beginning of Mars' spring season. Activity increased as spring continued, but fell off again for about two weeks during a dust storm. As the dust storm faded away, dust devil activity came back. In the mid-afternoons as the summer solstice approached, dust devils were a very common occurrence on the floor of Gusev crater. The early-spring dust devils tended to move southwest-to-northeast, across the dust devil streaks in Gusev seen from orbit. Increasingly as the season progresses, the dust devils are seen moving northwest-to-southeast, in the same direction as the streaks. Scientists are watching for the big dust devils that leave those streaks.