As autumn got underway in early May 2003, large dust storms began to form on the northern plains and sweep their way eastward--and sometimes southward--bringing colder air down from the north polar cap, now shrouded in darkness and clouds. This early autumn view, assembled from Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images, shows an eastward-moving dust storm on the plains north of Cydonia and western Arabia Terra. The storm is nearly as big as the continental United States are wide, from west to east. Credit: NASA/JPL/Malin Space Science Systems
