The eminence from the Royal Observatory in Greenwich wanted to reassure his audience with light humor. "You may sleep quietly in your beds," said Edward Walter Maunder at a meeting of the British Astronomical Association in 1909, "without any fear of invasion from Mars."
Most of Maunder's listeners knew of "The War of the Worlds," the 1898 science-fiction novel by H.G. Wells, but few would have lost sleep due to anxiety over a Martian attack. Yet for years people had taken seriously the claims of Percival Lowell, an American astronomer who insisted on the existence of an extraterrestrial civilization.
Lowell was a member of the Boston elite whose name today is attached to the Lowell Observatory in Flagstaff, Ariz., and who is forever associated with the solar system's fourth planet. He is perhaps more responsible than anyone for what David Baron, a science journalist, calls "the Mars craze." In "The Martians," Mr. Baron gives a briskly written account of planetary intrigue and obsession around the turn of the 20th century.
At the time of Lowell's birth in 1855, scientists already knew much about Mars. Ancient stargazers around the world had noticed its peculiar color and retrograde motion. In the 16th and 17th centuries, Europeans began to record observations and offer new ideas. Nicolaus Copernicus (1473-1543) proposed that Mars and the rest of the planets revolve around the sun. Soon after, Johannes Kepler (1571-1630) used data recorded by Tycho Brahe (1546-1601) to plot their orbits. Others began to chart the Martian surface. In 1666 Giovanni Cassini (1625-1712) reported that the length of a Martian day -- the time it takes to complete one rotation -- was 24 hours and 40 minutes. His estimate was too long by about 3 minutes. Astronomers corrected it in the 1830s.