Percival Lowell did much to stimulate our speculations about the possibility of life on Mars with his reported observations of canals on Mars. How did it all get started?
Mars has long captured the imagination. Ancients saw its blood red color and named it for the god of war. Modern probes reveal that its reddish color is caused by rusty iron in its soil. Probes to Mars also search for water and evidence of present or past life on Mars.
Schiaparelli's Canali
In 1877 Mars approached Earth very closely. During this opposition, Giovanni Schiaparelli, an Italian astronomer, observed dark markings on the surface of Mars. To Schiaparelli these dark lines resembled channels that were not in any way artificial. He called them canali, which is the Italian word for channels.
Think about the English Channel versus the Panama Canal. Schiaparelli was thinking about natural features more like the English Channel. However to English speakers the word Italian word canali suggests manmade features such as the Panama Canal. Popular English accounts of Schiaparelli's observations suggested canals rather than channels.
Percival Lowell
Percival Lowell was not a professional astronomer. He was a wealthy businessman without formal training in astronomy. When Lowell read popular accounts of Schiaparelli's canali, he became fascinated by the possibility of canals and life on Mars.
Having the needed financial resources, Lowell moved from Boston to Flagstaff, Arizona and in 1894 built an observatory on a nearby mountain. The Observatory still exists as Lowell Observatory. Lowell devoted the rest of his life to studying these canals on Mars.
Lowell drew very detailed maps of Martian canals. He postulated that Mars was a dying desert world whose inhabitants built a planet wide system of canals. These canals transported precious water from the polar icecaps to the warmer equatorial regions where the purported Martians lived. Lowell was also a talented popularizer. He wrote books and gave lectures to popularize the idea of Martian canals and a planet wide civilization on Mars. Lowell's ideas captured the public imagination.
The Controversy
There was a problem however. Other astronomers, even those using larger telescopes, such as the 100 inch Hooker telescope on Mt. Wilson, then the world's largest, did not see Martian canals. Most professional astronomers therefore did not take Lowell's speculations seriously.
The space program finally settled the controversy. Probes to Mars show no sign of canals or a Martian civilization.
Pathological Science
Was Lowell a liar or con man? Probably not. Historical evidence suggests that Lowell really did believe he saw canals on Mars. Perhaps his lack of formal scientific training made him more likely to speculate on limited data.
When we look at things near the limit of our ability to see or resolve, our brains tend to interpret what we can barely see as what we want to see. For example, people who haven't eaten in several days might see their favorite meals. Lowell really wanted to see and believe in canals and Martians. So his brain may have interpreted faint barely visible markings on Mars as a planet wide system of canals. Lowell was not a liar, but it is likely that his brain lied to him subconsciously.
Lowell's canals on Mars are a good example of what is often called pathological science. When data are at the limit of what we can discern, fallible humans often interpret the data incorrectly.
Further Reading
Morrison, D., Wolff, S., and Fraknoi, A. Abell's Exploration of the Universe 7th ed., Saunders, 1995.
Chaisson, E. and McMillan, S. Astronomy Today, 4th ed., Prentice Hall, 2002.
 |
