Journées du Patrimoine Part Two: The Paris Observatory

Me outside of the Paris Observatory

When you think Paris, you don't exactly think stargazing. Yet historically, many important astrological calculations and discoveries were made right here, over in the 14th Arrondissement, at the Paris Observatory, the world's oldest operating observatory. Back when it was commissioned in 1666, it wasn't exactly in city borders. It was actually considered a failure of Louis the XIV and his minister Colbert as it was utilized by very few scientists, most considering the observatory to be too far from the city center. Back in those days, setting up a telescope on your apartment roof could get you some real astrological data and it wasn't considered nearly so sketchy, so many scientists just preferred to stay at home instead of taking the hike all the way to the observatory.

A star chart of the Southern Hemisphere made in 1755. I just love how scientists back in the day had the time to incorporate so much beauty into their instruments and observations. I'm not sure what my professor would say if I started decorating my images of neurons with little illustrations and hanging up the best around the office in ornate gold frames.

A celestial globe from 1759: once again, I can't get enough of how ornate science used to be.

At first, mapping in the Paris Observatory wasn't concerned with what lay in the heavens as much as the world in which these scientists lived. More accurate maps made here shortly after the king's commisioning of the building led to his losing about a fifth of his country when more proper estimates significantly shrunk the estimated area of France. Aiding in its measurements for mapping, the Observatory was placed along the axis of the French meridian, a point of political competition against Britain's Grenwich (and now the prime) meridian. Little is left of France's meridian beyond a series of commemorative medallions.

Giant slabs of wood like this were used for polishing big lenses and mirrors. Traditionally, the Paris Observatory was home to some of the largest, most powerful lenses when it was young. This mirror polisher featured here served to polish a mirror on the telescope that a Swiss team used in 1995 to identify the first planet outside of our solar system, named 51 Peg b.

I loved the giant telescopes on display.

Much more than mapping was happening at the Paris Observatory. In 1676, a Danish astronomer named Rømer working at the observatory became the first man to measure the speed of light, previously assumed to be infinite or immeasurable. In 1851, Foucault first demonstrated the rotation of the earth with a pendulum set up in this observatory. (A replica was soon after placed in the Pantheon for the public.) Delambre and Méchain, who worked within these walls, spent years standardizing the measure of the meter. In more recent times, the first electric camera was invented in the observatory by Lallemand (1951). Since 1960, light pollution has prohibited the use of the observatory of star gazing but it still stands, a testament to the great work of scientists in France over the past several centuries, a place where researchers still toil, and a public place for learning.