Pierre Charles Le Monnier

Pierre Charles Le Monnier (20 November 1715 – 3 April 1799) was a French astronomer. His name is sometimes given as Lemonnier.

Le Monnier was born in Paris, where his father Pierre (1675–1757), also an astronomer, was professor of philosophy at the college d'Harcourt.

His first recorded astronomical observation was made before he was sixteen, and the presentation of an elaborate lunar map resulted in his admission to the French Academy of Sciences, on 21 April 1736, aged only 20. He was chosen in the same year to accompany Pierre Louis Maupertuis and Alexis Clairaut on their geodetical expedition for measuring a meridian arc of approximately one degree's length to Torne Valley in Lapland. In 1738, shortly after his return, he explained, in a memoir read before the Academy, the advantages of John Flamsteed's mode of determining right ascensions.

His persistent recommendation of British methods and instruments contributed effectively to the reform of French practical astronomy, and constituted the most eminent of his services to science. He corresponded with James Bradley, was the first to represent the effects of nutation in the solar tables, and introduced, in 1741, the use of the transit-instrument at the Paris Observatory. He visited England in 1748, and, in company with the Earl of Morton and James Shore the optician, continued his journey to Scotland, where he observed the annular eclipse of 25 July.

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