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Who really made the first telescopic observation?

Date: 14-Jan-09
Author: U.K. Royal Astronomical Society

This year the world celebrates the International Year of Astronomy (IYA2009), marking the 400th anniversary of the first drawings of celestial objects through a telescope. This first has long been attributed to Galileo Galilei, the Italian who went on to play a leading role in the 17th century scientific revolution. But astronomers and historians in the UK are keen to promote a lesser-known figure, English polymath Thomas Harriot, who made the first drawing of the Moon through a telescope several months earlier, in July 1609.

By 1609, Harriot had acquired his first 'Dutch trunke' (telescope). He turned it towards the Moon on 26 July, becoming the first astronomer to draw an astronomical object through a telescope. The crude lunar sketch shows a rough outline of the lunar terminator (the line marking the division between night and day on the Moon, as seen from the Earth) and includes a handful of features like the dark areas Mare Crisium, Mare Tranquilitatis and Mare Foecunditatis.

(Left) Portrait reputed to be of Thomas Harriot (1560-1621), though there are discrepancies in the documentation which casts doubt on the identification. The portrait was painted in 1602, when Harriot would have been 42. Courtesy: East Carolina University
(Right) Original manuscript of the map of the Moon made from telescopic observations by Thomas Harriot (1560-1621), whose lunar observations predated those of Galileo. Courtesy: Lord Egremont / Galaxy
(Click on image for larger version)

Harriot went on to produce further maps from 1610 to 1613. Not all of these are dated, but they show an increasing level of detail. By 1613 he had created two maps of the whole Moon, with many identifiable features such as lunar craters that crucially are depicted in their correct relative positions. The earliest telescopes of the kind used by Harriot (and Galileo) had a narrow field of view, meaning that only a small portion of the Moon could be seen at any one time and making this work all the more impressive. No better maps would be published for several decades.

Despite his innovative work, Harriot remains relatively unknown. Unlike Galileo, he did not publish his drawings.

Full story: Thomas Harriot: A telescopic astronomer before Galileo