Mars has been a source of fascination and speculation ever since the ancient Egyptians observed its blood-red hue and named it for their god of war and plague. But it wasn't until the 19th century when "canals" were observed on the surface of the Red Planet—suggesting the presence of water—that scientists, novelists, filmmakers, and entrepreneurs became obsessed with the question of whether there's life on Mars. Illustrated throughout, Marc Hartzman's history includes such figures as Christiian Huygens, Ray Bradbury, Elon Musk, and Marvin the Martian.