history of the Paris Observatory

Beginning with the invention of the refracting telescope by Galileo in 1609, the sky revealed an unsuspected richness: moon craters, Venus phases, sunspots, all that changed the understanding of the universe, and prompted to improve the instrumentation in order to allow new discoveries.

Astronomy is not only contemplative; since the antiquity, it contribues to latitude determinations. However the telescopes were improved allowing precise sights; the invention of the regulating pendulum by Huygens, in 1657, allowed to manufacture good clocks. The astronomer was then able to give latitudes and longitudes with the accuracy needed by sailors, soldiers, travellers: only were missing the way to build good instruments and to educate the necessary staff.

Meanwhile, new ideas implied a changing of the minds: the scholastic science receded in front of what would become the modern science. Everywhere in Europe Societies and Academies are created where collective researchs begin. In France, this scheme miscarries, the discoverers prevail over the experimenters; the latters solicit the State, since they need a considerable financial support.

These circumstances lead some members of the scientific community, in 1665, to elaborate the detailed project of a "Science and Art Company", whereas one of them, the physicist and astronomer Auzout insists on the urgent need for an astronomical observatory in a dedicace to the King "Sire, the glory of your Majesty is concerned..."

Epistle of Auzout to the king Louis XIV

Louis XIV and Colbert fulfil these wishes: the Royal Academy of Sciences opens its introductory seance on december 22, 1666 and a building site is purchased on march 22, 1667. Both creations are linked together since the Observatory was planned to be used as office for the academicians (seance hall and laboratories) as well as where to put the instruments dedicated to the astronomical observations.

Creation of the Paris Observatory (1667), engraving by Thibault, from a painting by Charles Lebrun. Colbert presents the members of the Science Academy to the King.

On june 21, 1667, summer solstice, the mathematicians of the Academy map the meridian and other directions needed for the erection on the ground on the current site of the building. The median plane of the building will henceforth define the meridian line of Paris, the reference meridian for France.

Drawing of the medal which has been put in the foundations of the Observatory.

The Observatory did not become the national research center though out by Colbert. Apart from a "Cabinet des machines" which was used as a depository for the Science Academy up to 1740, the Observatory has been devoted from the beginning to the astronomical activity: the academicians did not give expression to their will to work or to convene in a place so far from the center of Paris at that time.

General Map of All the Buidings of the Observatory and Surroundings, by M. D'Orbay, november 8, 1692. (National Library, cabinet des estampes).

From S. Débarbat, S. Grillot, J. Lévy