<p dir="ltr">Summer and winter leave their marks on <a href="http://science.nationalgeographic.com/science/space/solar-system/mars-article/">Mars</a>, too, as seen in a crater slope that is lined with markings that advance and retreat with the seasons. (See also: "<a href="http://video.nationalgeographic.com/video/science/space-sci/exploration/mission-mars-sci/">Mission To Mars</a>".)</p><p dir="ltr">Called "recurrent slope linea," the markings on the slope of the crater near <a href="http://mars.jpl.nasa.gov/gallery/atlas/valles-marineris.html">Valles Marineris</a> on Mars grow longer in warm months, and then retreat as the weather cools over the course of the Martian year. Scientists suspect that briny water or liquid carbon dioxide under the surface warms and colors the lines during warmer months on Mars.</p><p dir="ltr"><a href="http://www.jpl.nasa.gov/news/news.php?release=2013-361">Captured by NASA's Mars Reconnaissance Orbiter</a>, the changes were seen in the spacecraft's regular overflight of the crater near the Martian equator.</p><p dir="ltr"><em>—Dan Vergano </em></p>