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Astro*Dictionary by Michael Erlewine





1 article for "Richer, Jean"

Richer, Jean [Astro*Index]


(1630-1696) French astronomer. Died at Paris.

A member of the French Academy of Sciences, he led an expedition into French Guiana (near the equator) to make precise observations of Mars, while Cassini performed the same observations at Paris. Their work yielded the first good value for the parallax of Mars and for the AU (Astronomical Unit). Richter also found that a pendulum swung more slowly near the equator, which led Newton to conclude that the shape of the earth was that of an oblate spheroid, buldging at the equator.

See also:
♦ Cassini, Giovanni Domenico ♦ Geocentric Parallax



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