The University of Chicago

373 W. Geneva St, Williams Bay WI 53191 (Latitude 42 34.2, Longitude -88 33.4)
Look Through a Large Telescope at the Moon, Saturn, Nebulae, Star Clusters and More at Yerkes Observatory!

From season to season the evening sky changes slowly and reveals many different celestial wonders visible with, and without, optical aid. Every month during the year, on select weekday and weekend evenings, Yerkes Observatory offers observing sessions with our 24-inch diameter reflecting telescope, weather permitting, for participants who are age 10 and up.

We currently have availability for additional registrants on these dates in August:

August 25th, 26th, 27th and 28th

Plan to arrive at the Observatory by 8:30 pm. Programs begin promptly at 8:45 pm.

Summer public observing events at Yerkes are very popular and sell out quickly. Space on each tour is limited and subject to availability. Sessions last approximately two hours.

The cost to participate is $30 per person, payable the evening of the event for groups of one to three people. Reservations are required and can be made only by email at No phone calls please. Please email questions also.

Groups of four or more will be asked for a 50% deposit by credit or debit card ($15 for each person), refundable only if the event is cancelled due to weather conditions. The balance will be due for the participants who come to the Observatory the evening of the event. Reservations for groups of four or more are not fully confirmed until the deposit is received.

When requesting reservations include an email address that can be accessed the day of the event, a cell phone number of the group organizer, and the number of people in the party. An Observatory representative will send a reply that includes additional information and instructions pertinent to your visit.

Scheduled event dates are removed from the above listings as quickly as possible after each sells out. We do not schedule public viewing for about four evenings before and four evenings after full moon due to excessive sky brightness. Full moon in August occurs on the 10th.

Public observing dates for September will be posted here about August 25th.

Participants must be physically fit and able to climb 40 steep, winding stairs from the ground floor of the building to the observing dome of the 24-inch reflector. Sensible shoes are required (no high heels, flip flops, open-toed sandals, etc.).

Programs begin with a brief introduction to the night sky with the unaided eye. Binoculars can help to enhance your stargazing experience at Yerkes, but are not necessary. During summer evenings from the dark sky environment at Yerkes you may see superb views of planets, constellations, hundreds of stars, an occasional meteor, the Milky Way and artificial satellites.

For information about regularly scheduled Saturday tours, weekday tours, and other events, please click here.