These images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter show how the appearance of dark markings on Martian slope changes with the seasons. The marks, called recurrent slope linea, extend down slopes during warmer months and fade away during cooler months. This animation shows the same location at several times of year. The location is in a crater on the floor of Valles Marineris, near the Martian equator.
Photo credit: NASA/JPL-Caltech/University of Arizona
Note: For more information, see PIA17605: Long, Recurring Linear Marking on Martian Slope, PIA17606: Seasonal Changes in Dark Marks on an Equatorial Martian Slope, PIA17607: Maps of Recurrent Slope Linea Markings on Mars, and NASA Mars Spacecraft Reveals a More Dynamic Red Planet.