Named after the Roman god of war, Mars has fascinated people for thousands of years. Did you know that... A Martian year is 687 Earth days, almost twice as long as a year on Earth. Mars's biggest valley, Valles Marineris, is four times as deep as the Grand Canyon! Scientists think that Mars, now rocky and barren, once had an ocean, rivers, and a thicker atmosphere. Explore the wonders of Mars, the Red Planet, with science writer Seymour Simon in this updated edition filled with full-color photographs and spacecraft images-- Source other than the Library of Congress.

Originally published: Mars. New York : William Morrow, Ã1987 ; and, Destination: Mars Ã2000.