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Jeremiah Horrocks, one of the great scientific minds of the 17th century, was the first man to observe the transit of Venus across the sun. Born in 1619 as the son of a poor farmer in Toxteth (near Liverpool), Horrocks lived a generally impoverished life. At the age of thirteen, Horrocks entered Emmanuel College, Cambridge, where he learned astronomy.

Based on Kepler's laws of planetary motion, Horrocks calculated that Venus would transit the sun (that is, pass between the sun and Earth) at 3pm on December 24, 1639. Horrocks used a telescope pointed at the sun, with a sheet of paper in front of the eyepiece (onto which the image of the sun would be projected), in order to take measurements of Venus's transit path, angular size, and orbital velocity.

From these measurements, he derived a value for the solar parallax which was smaller than anyone had found before, thereby showing that the distance between the sun and Earth was (and still is) greater than generally thought in the 17th century. He detailed his discovery in the treatise Venus in Sole Visa (literally translates to "Venus in the Face of the Sun").

Horrocks died tragically just over a year later, on January 3, 1641, but not before Venus in Sole Visa earned him a place in the record books. The cause of death is unknown.

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