Jérôme Lalande
French astronomer (*1732 – †1807)
Joseph Jérôme Lefrançois de Lalande (French: [lalɑ̃d]; 11 July 1732 – 4 April 1807) was a French astronomer, freemason and writer. He is known for having estimated a precise value of the astronomical unit (the distance from the Earth to the Sun) using measurements of the transit of Venus in 1769.
Biography
Lalande was born at Bourg-en-Bresse (département of Ain) to Pierre Lefrançois and Marie‐Anne‐Gabrielle Monchinet. His parents sent him to Paris to study law, but as a result of lodging in the Hôtel Cluny, where Joseph-Nicolas Delisle had his observatory, he was drawn to astronomy, and became the zealous and favoured pupil of both Delisle and Pierre Charles Le Monnier. Having completed his legal studies, he was about to return to Bourg to practise as an advocate, when Le Monnier obtained permission to send him to Berlin, to make observations on the lunar parallax in concert with those of Nicolas Louis de Lacaille at the Cape of Good Hope.
The successful execution of this task obtained for him, before he was twenty-one, admission to the Academy of Berlin, as well as his election as an adjunct astronomer to the French Academy of Sciences. He now devoted himself to the improvement of the planetary theory, publishing in 1759 a corrected edition of Edmond Halley's tables, with a history of Halley's Comet whose return in that year he had helped Alexis Clairaut and Nicole-Reine Lepaute to calculate. In 1762, Delisle resigned the chair of astronomy in the Collège de France in Lalande's favour. The duties were discharged by Lalande for forty-six years. His house became an astronomical seminary, and amongst his pupils were Jean Baptiste Joseph Delambre, Giuseppe Piazzi, Pierre Méchain, and his own nephew Michel Lefrançois de Lalande.
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