A view from the top of the world
Located at an altitude of 2,877 meters (9,439 feet) in the French Pyrenees, the Pic du Midi Observatory has been a premier site for astronomical observation for over a century. Construction began in 1878, a monumental task that required materials to be hauled up the mountain by men and mules. The site's primary advantage is the exceptional stability and clarity of the air. This high altitude places the observatory above much of the atmospheric turbulence and water vapor that can blur images taken at lower elevations, providing astronomers with extraordinarily sharp views of the cosmos.
The observatory is not a single instrument but a collection of domes and telescopes. The first major dome, the Baillaud Dome, was completed in 1908 and initially housed a powerful reflector telescope used to discredit the theory of Martian canals in 1909. Over the decades, more instruments were added. In the 1930s, astronomer Bernard Lyot took advantage of the pure skies to invent and perfect the coronagraph, a device that creates an artificial eclipse, allowing for the study of the Sun's faint corona without a natural eclipse. This invention changed solar science. While the Arago name is historically associated with the Paris Observatory, the important instrument for lunar mapping at Pic du Midi was the 1.06-meter (42-inch) telescope installed in the Gentilli Dome in 1963.