Astronomy magazine visits Yerkes Observatory

Posted by Chris Raymond
on Tuesday, December 07, 2010

Did you know that the world’s largest refracting telescope is located less than an hour from Astronomy magazine’s headquarters? Founded in 1897, Yerkes Observatory sedately sits on the shore of Geneva Lake in Williams Bay, Wisconsin. On December 3, 2010, the staff of Astronomy, its publisher, and its senior graphic designer received a behind-the-scenes tour of this historic facility.

The crew of Astronomy stands beneath the “business end” of the world’s largest refracting telescope at Yerkes Observatory in Williams Bay, Wisconsin, December 3, 2010. Chris Raymond photo

While Yerkes houses several large scopes of varying size, it’s the 40-inch refracting telescope that really put this otherwise sleepy village on the map, establishing the observatory as the birthplace of modern astrophysics. Just picture a refractor on steroids and you can imagine the impression felt by the Astronomy group when they first glimpsed this 63-foot-long instrument. The lens at the top of this scope is more than a yard wide!

Richard Dreiser, director of special programs and good friend of several senior members of the Astronomy staff, explained the history of this observatory during the tour. Starting with the facility’s gorgeous architectural details and the important research still conducted there, the 117-year-old telescope within its massive brick-wall dome undoubtedly proved the highlight. (The refractor was first exhibited during the World’s Columbian Exposition in 1893, four years before its permanent installation.)
Since 1897, this dome has sheltered the 40-inch refractor at Yerkes observatory. The slit in the roof opens to 11 feet wide and is 85 feet long. Chris Raymond photo

Another unforgettable moment occurred when Dreiser activated the 37.5-ton elevating floor on which the Astronomy group stood. To support the weight of this massive telescope, its base sits fastened to solid ground, and the 75-foot-diameter floor surrounding it rises or lowers up to 22 feet, like a donut on a wooden dowel, so observers can reach the eyepiece depending on the scope’s position. Unbelievably, the massive floor actually collapsed once, in May 1897, shortly after the observatory opened.
The floor beneath the world’s largest refractor raises or lowers up to 22 feet so observers can reach the eyepiece as the telescope’s orientation changes. Chris Raymond photo

Fortunately, nobody stood on the floor at the time of the collapse, and the Astronomy group encountered no mishaps. Instead, it proved thrilling to stand on the very spot where Albert Einstein and famous astronomers like Carl Sagan and E.E. Barnard once stood and soak in the rich history this site has contributed to astronomy.

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