Jean Richer
Jean Richer (* 1630 ; † 1696 in Paris) was a French astronomer . He was an employee of the astronomer Cassini I .
On behalf of the French government, he made a trip to Cayenne from 1671 to 1673 to determine Mars during its perigee . A comparison with observations at other locations made it possible to determine the distance between the Sun and Mars using the parallax .
Richer determined exactly the lengths of an arc of a meridian and thereby revealed that the earth is flattened at the poles . He also found that a seconds pendulum in Cayenne near the equator had to be shorter than in Paris because Cayenne was further away from the center of the earth. This confirmed the hypotheses of Isaac Newton and Christiaan Huygens . In 1683 Philippe de La Hire confirmed this fact through another expedition.
Fonts
- Jean Richer: Observations astronomiques et physiques faites en l'isle de Caïenne . In: Académie Royale des Sciences (ed.): Mémoires de l'Académie Royale des Sciences depuis 1666 jusqu'à 1699 . tape 7 . Compagnie des Librairies, Paris 1729, p. 231 ( digitized on Gallica ).
Web links
- John J. O'Connor, Edmund F. Robertson : Jean Richer. In: MacTutor History of Mathematics archive .
- http://galileo.rice.edu/Catalog/NewFiles/richer.html
| personal data | |
|---|---|
| SURNAME | Richer, Jean |
| BRIEF DESCRIPTION | French astronomer |
| DATE OF BIRTH | 1630 |
| DATE OF DEATH | 1696 |
| Place of death | Paris |