Wisconsin’s Yerkes Observatory—stargazing through the world’s largest refracting telescope

Jun 29, 2018

Dan Koehler operates the world's largest Refracting telescope, built in 1897 at Yerkes Observatory
Credit Thomas Wilmer

Join Dan Koehler, Director of Tours and Programs at Yerkes Observatory. The 40” refracting telescope is the largest ever built in the world. Amazingly Yerkes Observatory’s stunning Gothic Romanesque architecturally significant structure and telescope first opened in 1897.  

Originally funded and operated by the university of Chicago, the 40” refracting telescope is open for public viewing, along with continuing scientific research. 

The Yerkes refracting telescope tube is 63 feet long and weighs 6 tons; all the gears (etc) to move it weigh 20 tons. It was the biggest telescope in the world in 1897, and remains still world's biggest refract
Credit Thomas Wilmer

Yerkes Observatory, situated in Williams Bay is just a 15-minute drive from downtown Lake Geneva, Wisconsin.

Stunning Gothic Romanesque architectural accents abound at Yerkes Observatory in Williams Bay, Wisconsin
Credit Thomas Wilmer
The Yerkes Observatory Dome is 90 feet in diameter and weighs 120 tons. The dome slit is 11 feet wide by 85 feet long.
Credit Thomas Wilmer
Yerkes Observatory entryway
Credit Thomas Wilmer

From the University of Chicago’s Yerkes Observatory website:

Throughout the year, weather permitting, Yerkes Observatory offers evening observing sessions for visitors age 10 and up.

Participants have a unique opportunity to view at a variety of fascinating celestial objects through either 40-inch refractor or 24-inch reflector telescopes..

Held several times throughout the year, star parties are your chance to see amazing celestial objects through telescopes on the lawn, enjoy the constellations, and try out cool astronomy activities for the whole family. 

Yerkes Observatory is a facility of the Department of Astronomy and Astrophysics of the University of Chicago. It was established in 1897 on Geneva Lake in Williams Bay, Wisconsin.

Until the mid-1960's, Yerkes Observatory housed all of the Department's activities. Today the 77-acre, park-like site in southeast Wisconsin provides laboratory space and access to telescopes for research and instruction.

Yerkes Observatory occupies a unique niche for the educational and the scientific community.

It bridges several important perspectives in formal and informal education. The history of astronomy and astrophysics of the observatory is a solid foundation for introducing all the important topics in current research as well as the practice of observational astronomy.

There is a huge range of opportunities for learning. Because of Yerkes' historical context, the world of professional and student astronomers and astronomy educators is drawn to the observatory.

These communities learn from one another, build relationships, and create programs, which result in enriched experiences and learning opportunities for young and diverse members of our society.

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