A Martian Sunset . ... Credit Copyright: IMP Team , JPL , NASA Explanation: You've had a hard day rolling past Martian rocks , so now just relax your APXS and enjoy the Martian sunset. The above pictures taken by Mars Pathfinder highlight how clouds vary during the end of a Martian day. ... Clouds on Mars can be water or carbon dioxide based, depending on conditions , whereas Earth's clouds are all water based. ... NASA Official: Jay Norris. ... U. Based on Astronomy Picture Of the Day ...