Sunday, June 8, 2008

Observatoire de Paris

The Paris Observatory was completed in 1672 and has associations with several famous astronomers. It was here that Ole Rømer measured the speed of light, and that Christian Hyugens discovered the rings of Saturn. Outside the Observatory is a statue of Le Verrier, the discoverer of the planet Neptune.
Its foundation lay in the ambition of Jean-Baptiste Colbert to extend France's maritime power and international trade in the 17th century. Louis XIV promoted its construction starting in 1667. The architect was Claude Perrault, whose brother Charles was secretary to Colbert and superintendent of public works. Optical instruments were supplied by Giuseppe Campani.

The building, located directly south of the Luxembourg Gardens, was extended in 1730, 1810, 1834, 1850, and 1951. The last extension incorporated the spectacular Meridian Room designed by Jean Prouvé.

The world's first national almanac, the Connaissance des temps was published by the observatory in 1679, using eclipses in Jupiter's satellites to aid sea-farers in establishing longitude. In 1863, the observatory published the first modern weather maps. In 1882, a 33-cm astrographic lens was constructed, an instrument that catalysed the international Carte du Ciel (Map of the Heavens) project begun in 1887, but never completed. It was expected to take 10-15 years, but after many decades of work (which included the discovery of several double stars and publication of a directory in 1958), the project was abandoned when computer capabilities made the equipment at this observatory obsolete.

In November 1913, the Paris Observatory, using the Eiffel Tower as an antenna, exchanged sustained radio signals with the United States Naval Observatory to determine the exact difference of longitude between the two institutions.
It was also the home to the International Time Bureau until its dissolution in 1987. Even so, the Paris Observatory is important in that it is the world’s oldest observatory still in operation. It exists today as a body of the Ministry of Higher Education with a status close to that of a university. It offers four graduate programs in astronomy and astrophysics and is responsible for diffusing knowledge to the public. It is the largest national center for research in astronomy, counting a full 30% of all French astronomers among its staff.

Web site in English:

Two-hour tours by appointment only (Tuesday or Thursday at 2 pm); send an E-mail to:

Observatoire de Paris
61, avenue de l’Observatoire, Paris 14
Telephone 01 40 51 23 97
Métro: Denfert Rochereau (lines 4 or 6), or RER Port Royal (line B)

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