Horrocks, Jeremiah

Horrocks or Horrox, Jeremiah

(both: hŏr`əks), 1618?–1641, English astronomer. He made the first observation of the transit of Venus. His Venus in sole visa, which narrates this experience, was printed by Hevelius in 1662. The transit occurred on Nov. 24, 1639; Horrocks watched the small shadow of the planet move part way across the disk of light on a white screen, where the sun's image was focused through a telescope. Other fragments of his works besides the Venus were edited by John Wallis (1672). Horrocks estimated more correctly than anyone else had yet done the distance of the sun from the earth.

Horrocks, Jeremiah


(also Horrox). Born circa 1617; died 1641. English astronomer.

Horrocks introduced improvements in the theory of lunar motion. Even before I. Newton’s discovery of the law of universal gravitation, he had conjectured that the disparities in the lunar motion were the result of the perturbing influence of the sun, and he noted several irregularities in the motions of the Saturn and Jupiter. Horrocks calculated in advance the transit of Venus across the sun’s disk (1639) and was the first to observe the phenomenon.

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