Credit: NASA/JPL/Malin Space Science Systems

Autumn on the martian northern plains means clouds and dust storms. 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. In this image, north is toward the top, east to the right, and sunlight illuminates the scene from the lower left.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, California. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, California and Denver, Colorado.