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 Jupiter and its Moons, Galaxies, 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 are now accepting reservations for these April dates:

April 23rd, 26th, 27th:
The programs begin at 8:45 pm. The building opens at 8:30 pm.

Please specify "early program" or "late program" with your request when inquiring about the April 17th or 18th sessions.

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 90 minutes. Scheduled sessions can be canceled due to adverse weather conditions (clouds, rain, high winds) and in rare circumstances, Observatory event conflicts that arise after public observing dates have been announced.

The cost to participate is $30 per person, payable the evening of the event by cash, VISA or Mastercard. Reservations are required and can be made by email only at

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.

Public observing dates for May 2015 will be posted here about April 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. Standing for about one hour on the telescope's elevating floor is required. Sensible shoes must be worn -- we do not allow high heels, flip flops, or open-toed sandals for safety reasons. Plan to dress appropriately for possible cool spring evenings. The Observatory dome is not heated.

During spring evenings from the dark sky environment at Yerkes you may see superb views of the moon, planets, constellations, hundreds of stars, star clusters, nebulae, galaxies, an occasional meteor and artificial satellites. Binoculars can enhance your viewing experience, but are not necessary.

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