Mars

There are three planets other than Earth in the inner solar system. The innermost is Mercury: tiny, barren, and hard to observe as it is located near the Sun. Next comes Venus, the planet nearest in size and mass to Earth, but swathed in clouds; a bland, featureless ball through the small telescope. Mars, half again as far from the Sun as Earth, is different. Features are distinguishable on its surface, and it sometimes shows polar ice caps that look much like Earth's.

Early observations of Mars by Giovanni Schiaparelli showed the existence of what Schiaparelli called canali, meaning channels. The existence of somewhat linear, light and dark channel-like features on Mars is affirmed by many other scientists, but the Italian word canali quickly acquired its popular and inaccurate meaning: canals. Water can cut a channel, but only intelligent life can build a canal.

The excitement of this discovery spurred a man named Percival Lowell in 1894 to leave his Boston home for Flagstaff, Arizona, where he founded the observatory that bears his name. Lowell spent the rest of his life studying Mars through the 24 in (61 cm) refracting telescope on Mars Hill above Flagstaff, and became convinced that intelligent life existed on the red planet. Lowell's drawings became increasingly complex as he observed and reobserved the planet, and he devoted himself to convincing the public that Mars was indeed inhabited.

Although Lowell Observatory soon became the site of fundamental advances in astronomy, such as the 1930 discovery of the solar system's outermost planet, Pluto, Percival Lowell was wrong about Mars. In 1976 two unmanned spacecraft, Viking 1 and Viking 2, landed at different points on Mars's northern hemisphere. They carried experiments designed to test the Martian soil for the presence of microorganisms, and ultimately found nothing. The expedition had initially looked promising as one experiment yielded reactions suggestive of life forms, but further analysis revealed that the reactions were not biological. The Martian terrain bears an eerie resemblance to some of the desert landscapes not so far from the hill where Lowell spent so many nights at his telescope.