The Observatory of Saint Michel and its history






At the beginning

Towards the end of the 19th century, observatories situated in large towns were adversely affected by two major factors:
(a)  industrial pollution which made the atmosphere too dense
(b)  city lights which created a disturbing halo effect in the skies.

As a result of these two problems, came the idea to build a brand new observatory in a “clean” site. The war put a temporary stop to the project; it wasn’t until 1924 that things began to move again.

The first stage was to identify the ideal site. Many regions were selected for various economic or political reasons: Sardinia, Corsica and the Alps. It was only when a certain Professor Danjon established an exhaustive list of scientific “musts” that the region of the Alps of High Provence and more closely, the area around the town of Forcalquier, was selected. This was in 1929. Around 1933, the specific site of the Aurifeuille Plateau was finally chosen, due to easy access and solid ground able to withstand the weight of all the necessary equipment.

Interestingly, as far back as 1603, the Dutchman Godefroi Wendelin built the first observatory on French soil not far from here, at Lardiers.

Unfortunately, finding the money to finance the project proved difficult, and for many years astronomers had to make do with a small telescope of 80 cm temporarily installed in a neighbouring site. The CNRS (National Scientific Research Centre) which was created in 1936 by the Popular Front, acquired the necessary land and building finally started in 1938.

In 1943, the very first telescope with 120 cm diameter became operational, after a long and troubled history. This telescope was originally conceived by the great physicist Léon Foucault towards the middle of the 19th century for the Paris Observatory (at that time 120 cm was the largest telescope possible). The mirror was built at Saint-Gobain in 1863 and when it was delivered to the Paris site, resources were unavailable and so Foucault had to start polishing it himself!

The Universal Exposition of 1878 found the project challenging and provided further funding to mount the telescope. However, many technical faults were discovered and the project was abandoned for almost half a century.

Work restarted between 1929 and 1936; then at the grand old age of 80, the 120 cm telescope gave its very first clear image on the 7th August 1943 in Provence.

The Observatory continued to develop after the war, focussing on the grand project of the 193 cm telescope. Initially conceived in 1924, its mirror was built in 1937, then refined around 1946. Financing the project was still difficult; however on the 7th July 1957, the telescope 50 tonnes of metal and a mirror weighing 1.200 kg, the first images were finally produced.

Over the years, constant improvements to the large telescope mean that, today, similar images can be achieved as with a 500 cm telescope of the 1950s!

The Observatory as it is today

Today, the Observatory can be visited. The visit is centred around the large Dome. Astronomers from all over the world carry out their specific projects in collaboration with around 60 people who work there on a daily basis. Not only does the Observatory have its own established astronomers, but it also offers its services, technicians and facilities to researchers the world over.