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He Charted the Moon Before Galileo, But You’ve Probably Never Heard of Him

Did Thomas Harriot keep his great discovery a secret to avoid decapitation?

by Eliza Strickland

From the April 2009 issue, published online March 31, 2009



On a clear night in July of 1609, English polymath Thomas Harriot pointed his “Dutch perspective glass” toward the crescent moon. The crude lunar map he sketched from his observations dates him as the earliest person known to have used a telescope to study a celestial object, beating Galileo Galilei by nearly four months. Over subsequent years Harriot produced remarkable drawings showing the locations of the moon’s craters and what he believed to be its oceans and coastlines. His cartography was not bettered for decades. So why does Galileo enjoy lasting fame while Harriot has been all but forgotten?

“The unfortunate thing is that Harriot never got around to publishing his maps,” says Stephen Pumfrey, a professor of history at Lancaster University in England, “and it was definitely a publish-or-perish situation.” Since Harriot never publicly claimed to have been the first to observe the moon’s surface in detail, Galileo got the credit.

Historians debate what made Harriot so reticent. In a paper published in February [pdf], Oxford professor Allan Chapman argues that Harriot was well-off and “was not an agenda- or career-driven individual,” whereas Galileo was determined to rise in station through his science. But Pumfrey also notes that both of Harriot’s wealthy patrons ended up imprisoned in the Tower of London, which may have discouraged him from crowing about his controversial discoveries. “Harriot had no one to protect him, because his patrons were worried about having their heads chopped off,” Pumfrey says. An exhibition of Harriot’s maps opens on July 23 at the Science Museum in London.

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