Oceans of the Solar System - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 216

ice. Arrhenius knew, too, of the debate surrounding the canals of
Mars. The publication of Giovanni Schiaparelli's map of Mars in 1877
had depicted a complex network of natural channels or canali on the
surface of the planet. This was a catalyst for some visionaries, princi-
pally the New England industrialist Percival Lowell, to see evidence of
civilization on Mars.
Lowell was possessed of an eclectic range of interests, and after
spending ten years in the Far East, where his cultural observations
were recorded in a series of topics, he returned to the United States
to pursue his great love of astronomy. Lowell built a state-of-the-
art observatory near Flagstaff in Arizona: the observatory is still
operational today, although the original 24-inch refracting telescope
he used is now something of a museum piece. Lowell dedicated the
latter part of his life to observing the surface of Mars. He saw Schia-
parelli's natural channels as canals, which he interpreted as a vast
network of irrigation for a drying planet. He even thought that he
saw cities connected by the channels, and patterns of colour change
on the surface through the year that he interpreted to be changes
in vegetation. The possibility of water and life on Mars fired the
imaginations of nineteenth- and twentieth-century novelists who
dreamed of fantastical, intelligent Martians, perhaps most famously
depicted as the callous and deadly invaders of H. G. Wells's The War
of the Worlds , armed with heat rays and tripod-shaped fighting
machines.
Arrhenius dismantled Lowell's claims with forensic skill. For a start,
the planet was simply too cold. The temperature at the surface could
be calculated ('easily', he said—but then he was a prodigious math-
ematician) from a consideration of the solar heat reaching the sur-
face of that distant and small planet, a little over half the diameter
of Earth. He obtained a value of −37 degrees Celsius, which was far
lower than Lowell's figure of +10 degrees Celsius. Lowell, though, had