The University of Chicago

373 W. Geneva St, Williams Bay WI 53191 (Latitude 42 34.2, Longitude -88 33.4)
Dome structure

The birthplace of modern astrophysics
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.

Yerkes Observatory is open for free public tours  every Saturday throughout the year. We also offer group touorrs special programs.

Upcoming Events

  • Special Observatory programs at Yerkes on Friday, July 3rd!

    The Observatory will be open for tours on July 3, 2015, for a per person fee. Tour times are 10:00 am, 11:00 am, 12:00 pm, 1:00 pm, 2:00 pm and 3:00 pm. Tours will last approximately 45 minutes and cover the history of the Observatory, an explanation of its unusual architectural design and details and an opportunity to see the world’s largest refractor (lens-type) telescope!

    The cost is $8 per person for visitors age 10 and older. Children under the age of 10 are admitted free of charge. Our unique gift shop will also be open all day.

    Our very knowledgable tour guides invite you to join us on July 3rd to avoid the expected large crowds on Saturday, July 4th and enjoy the Observatory at a leisurely pace.

    Yerkes will be open Saturday, July 4, 2015 for our usual free public programs at 10:15 am, 11:15 am, and 12:15 am. Donations are suggested.

    Questions should be emailed to , (the mailbox is monitored regularly every day) or you may call our office at 262-245-5555 before 2:00 pm on July 2nd. Our office will not be staffed on July 2nd after 2:00 pm, or any hours July 3rd through 5th.

  • Regular Saturday Tours
    Yerkes Observatory is open for free public tours every Saturday throughout the year. Programs begin at 10:00 a.m., 11:00 a.m., and Noon.

    For more information, click here
  • New Weekday Tours
    On most weekdays, between 9:30 a.m. and Noon, and between 1:30 and 4:30 p.m., you may schedule a thirty-minute tour, similar to the free Saturday tours. We charge $25 per group for a half-hour program, and $100 for a one-hour tour. If there are more than five, we charge an additional $5 per person.
    To schedule a tour, email: or call 262-245-5555, Extension 880. Be certain to include your cell/telephone number and email address.
  • Observe through a Big Telescope
    Throughout the year, weather permitting, Yerkes Observatory offers evening observing sessions for adults and kids aged twelve and up. Participants look at a variety of fascinating celestial objects through a large, modern 24-inch diameter telescope....

    For more inormation, more...
  • Yerkes Asteroid Day Event
    How interested are you in the giant pieces of rock floating through space? Believe it or not, there's a whole day dedicated to these rock chunks! This is a particularly fascinating and important area of research: tracking and tracing the paths of these asteroids and knowing whether they will ever collide (or have collided) with Earth. Yerkes Observatory will be holding an asteroid educational event from 6:30-8:30 pm on June 30th. There will be a presentation on this topic, and various asteroid models and activities.

    To register for the event, click here
  • 2015 Yerkes Astrophysics Academy for Young Scientists (YAAYS) Camps
    Every year, Yerkes Observatory scientists and educators offer a variety of summer camps revolving around STEM topics (Science, Technology, Engineering, and Math). The aim of Yerkes Observatory summer camps is to involve students in STEM based exploration to build a sense of confidence solving problems using the practices of science and engineering in an atmosphere that is active, engaging, and fun.

    For more info and applications, click here

The education programs are made possible in part through SOFIA Outreach at Yerkes Observatory.

University of Chicago Press release: Middle schoolers to explore sky with robotic telescopes

Yerkes Study Group (YSG)
The Yerkes Study Group was formed to explore the best use of Yerkes Observatory as a future site for a regional center for science education. To download the final report (pdf file) of the YSG click here
Yerkes Obs