This event is sold out. Join us for our final open house of 2025 on Saturday, October 4 from 6pm – 8pm! We are celebrating International Observe the Moon Night, which is an annual world-wide program that encourages observation, appreciation, and understanding of our Moon and its connection to NASA planetary science and exploration. We’re thrilled to be joined again by the Northwest Suburban Astronomers, who are volunteering their time to provide observing outside on our South Lawn if skies are clear. We’ll also have a special guest for you to meet, including Miss Kenosha Nellyka Dennis, plus engaging science demonstrations and activities, a scavenger hunt with prizes, and more for your family to enjoy. 

The open house will take place rain or shine. This does not include use of telescopes within the building. Reservations are required. Tickets for this event cost $5 per child and $10 for adults and are available online only. There will not be parking onsite at the Observatory. Ticket holders must park at Williams Bay School and board an accessible trolley that will run a continuous shuttle between the school and observatory during the Open House. See the official schedule of events below!