Mars From Afar
The Planet
This is Mars as it appeared in May 2002. It's early spring in the
Northern Hemisphere, whose seasonal carbon-dioxide frost cap has
begun its annual retreat. Other white areas in this composite are
clouds, some seen hovering over volcanoes such as Olympus Mons, the
dark round spot in the far left of the image. The huge canyon system
known as Valles Marineris is visible as a thick horizontal line in
the lower right. All told, Mars is about 4,200 miles in diameter, a
little over half as big across as the Earth.