The International Year of Astronomy (IYA), now under way, marks the 400th anniversary of the year that famed Italian astronomer Galileo began observing and documenting the heavens with increasingly powerful telescopes.

But in a paper in the current Astronomy & Geophysics, University of Oxford historian Allan Chapman argues that a less renowned astronomical pioneer deserves recognition as well. Thomas Harriot, an English mathematician, apparently turned a telescope to the sky even before Galileo did, producing a moon sketch that Chapman says is "the oldest known drawing of a telescopic body, made nearly four months before Galileo's first drawing."

Harriot's sketch, pictured above at left and dated July 26, 1609, is fairly rudimentary, but his moon maps became increasingly detailed as the years passed, as shown by the undated sketch at right. He remains relatively unknown for his contributions to astronomy, compared to Galileo at least, because he did not publish his work and, according to Chapman, never made a public claim for his milestone achievement.

Chapman notes that Harriot seems to have kept pace with his more famous contemporary, independently discovering sunspots in 1610 before Galileo had published or publicly presented his discovery of the phenomenon.

Even if Harriot remains overshadowed by Galileo and other famous names of astronomy, he will at least get his day this summer, when the IYA honors the anniversary of Harriot's first moon drawing at a July 26 event, Telescope400.

Photo credits: © Lord Egremont