The Birthplace of Modern Astrophysics

Yerks Conservatory Dome

Yerkes Observatory on Lake Geneva in Williams Bay

Free Public Tours and Special Viewings

Arial view of Yerks Observatory in Williams Bay, Wisconsin

Arial view of Yerks Observatory in Williams Bay, Wisconsin

Built in 1897, this is the largest refracting telescope in the world. The grounds are original to the landscape plan of 1898.

Free tours on Saturdays at 10:00am, 11:00am, and 12:00 (noon).

New Weekday Tours
If the tour guide is available, visitors may take a 30-minute tour weekdays (excluding Wednesdays) between 9:30 and 11:00 a.m. or 1:30 and 4:30 p.m. If there are five or more in your group, please make arrangements for a private program. Advanced reservations are recommended. The fee is $25.00. Contact Richard Dreiser at 262 245-5555, ext 880, or send email to: or, ring the doorbell and ask for the Tour Guide.

The university offers viewing in small groups (8 people or fewer) at various times of the year through the 24 inch reflecting telescope at night. It is a awesome treat to be one on one with a astronomer and seeing the universe; well worth the $25 admission. For information, see here for a list of dates.

At Yerks during the viewing  through the telescopes one must dress for the outdoors. The temperature is the same inside the dome as the outside.



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