YERKES OBSERVATORY

The Yerkes Observatory is located in Williams Bay, Wisconsin. It is operated by the Astronomy and Astrophysics Department of the University of Chicago. When he was created in 1897 by the astronomer George Ellery Hale, he was quickly baptized "the cradle of modern astrophysics". He was funded by businessman Charles T. Yerkes. It is the very symbol of the nineteenth-century professional observatory, the fruit of an era that is now over where quality observations can still be made near the major urban centers! Like other places in the world that had made the same geographical choice (the large telescope of the Center of Meudon in particular, so close to Paris), its builders ignored the proximity of Chicago or Milwaukee, favoring access to the observatory rather than a star sky worthy of the name. The beautiful park surrounding the cupolas and the buildings also plants the décor: One wonders why we wanted to make astronomy in this place! However, it should be put back into the context of the time, in 1897, when light pollution was not so catastrophic and the need for a high-level site was not so high. We cannot change the past, and at least this is where we can admire the world's largest bezel, impressive with its 101 cm diameter target manufactured by Alvan Clark, a great American optician who used glasses from France to design its objectives of such large diameter. Everything in this instrument breathes the image of Epinal of astronomy from the late nineteenth century: a huge dome, a bezel to the interminable tube resting on a particularly high statif… and it is easy to imagine some astronomy astronomers who are wearing the eye to the eye of this gear, to examine surprising details of the Martian surface or in the tormented atmosphere of Jupiter! For the rest, this observatory will not draw any tears from the eyes of the enthusiast, even if it is possible to observe behind the large telescope (provided the price is placed there). His visit will be done in a more general context, when we are passing through and his planning schedule allows.