Jean Picard

From Wikipedia, the free encyclopedia

This article is about the 17th century French astronomer. For the fictional Star Trek: The Next Generation captain, see Jean-Luc Picard.

Jean-Felix Picard (1620-1682)

Jean-Felix Picard (July 21, 1620 – July 12, 1682) was a French astronomer and priest born in La Flèche, where he studied at the Jesuit Collège Royal Henry-Le-Grand. He was the first person to measure the size of the Earth to a reasonable degree of accuracy in a survey conducted 1669-70, for which he is honored with a pyramid at Juvisy-sur-Orge. Guided by Maurolycus' and methodology and Snell's equipment design for doing so, Picard achieved this by measuring one degree of latitude along the Paris Meridian using triangulation along thirteen triangles stretching from Paris to the clocktower of Sourdon, near Amiens. His measurements produced a result of 110.46 km for one degree of latitude, which gives a corresponding terrestrial radius of 6328.9 km. The polar radius has now been measured at just over 6357 km. This was an error only 0.44% less than the modern value. This was another example of advances in astronomy and its tools making possible advances in cartography.