Exploring the Night Sky Tour Dates for Summer 2024

Exploring the Night Sky with the Great Refractor tour tickets for Summer 2024 are available now on our ticketing website! We’re pleased to announce new youth pricing for this experience starting in June. For youth ages 13-18, prices are now $85. Adult tickets are $140.

With only 12 tickets available for each tour, this exclusive evening illuminates the inner-workings of Yerkes Observatory after dark. Curated by our Telescope Team, each tour features a viewing of the cosmos with the largest refracting telescope in the world if skies are clear. If skies are not clear, we’ll delve into Yerkes vaults with 180,000 glass astronomical images, explore the evolution of astrophotography through over a century of equipment, and visit darkrooms in our subterranean chambers.

Regardless of atmospheric conditions, this is a two-hour immersion inside the observatory that changed the way we see the Universe. This is a night event, thus it’s an experience best enjoyed by ages 13 and up. Because of the historic construction of the building and domes, there are several flights of stairs (standard, steep, and tight spirals) that will be climbed and descended during both the clear and cloudy night programs. As such, this experience is not wheelchair accessible.

Exploring the Night Sky tours with the Great Refractor will take place on the following dates:

Saturday, June 15 from 9-11pm
Friday, June 21 from 9-11pm
Saturday, June 22 from 9-11pm
Friday, June 28 from 9-11pm
Saturday, June 29 from 9-11pm
Tuesday, July 2 from 9-11pm
**Note that there may be loud sounds with fireworks being set off nearby, so this tour will likely not be suitable for those with sensory sensitivities.**
Tuesday, July 9 from 9-11pm
**Note that there may be loud sounds with fireworks being set off nearby, so this tour will likely not be suitable for those with sensory sensitivities.**
Saturday, July 13 from 9-11pm
Friday, July 19 from 9-11pm
Saturday, July 27 from 9-11pm
Saturday, August 3 from 9-11pm
Friday, August 16 from 9-11pm
Saturday, August 17 from 9-11pm
Friday, August 23 from 9-11pm
Saturday, August 24 from 9-11pm
Friday, August 30 from 9-11pm
Saturday, August 31 from 9-11pm

Frequently Asked Questions

What weather and conditions are required for use of telescopes?

In order to safeguard the condition of our telescopes, we will observe when it is mostly clear (most stars visible), with humidity levels below 85%, wind speeds below 45 mph, there are no active air quality alerts, and the temperature is above freezing (32 degrees F).

We cannot guarantee clear skies on the night you scheduled, but in the event that the weather does not permit observing with our telescopes (or there are technical issues with the historic equipment), we guarantee a special, exclusive experience where you will explore the night sky from a historical perspective on our indoor evening tour.

What weather and conditions will cause an event cancellation?

If there is lightning or severe thunderstorm risk, we will cancel the event as a safety precaution. You will be fully refunded should we have to cancel because of weather.

Where is the event located?

Our address is 373 W. Geneva Street in Williams Bay, Wisconsin. Turn into our driveway at Geneva St. and Observatory Place by the Yerkes Observatory sign. Our parking lot is on the southeast side of the building. Stay left in the oval driveway and wind around to the lot. Keep veering left keeping the yellow home on your left. Please do not pull in front of the northside doors of the Observatory.

Our ADA spots are in the main parking lot in the southwestern corner of the lot. They adjoin the pathway to the south (lakeside) doors. We also have EV charging stations in our lot.

What should I be prepared for? Do I need to bring anything?

The observatory was built in 1897 and so the Great Refractor and the 24” telescopes is not easily accessible. There are several flights of stairs (standard, steep, and tight spirals) that will be climbed and descended during both the clear and cloudy nights. If you have concerns or would like to request accommodations, please contact us at at least 2 business days prior to your tour. Please note that we are an historic observatory, so while we will do our best to provide accommodations, we cannot guarantee them.

Light refreshments will be provided at the beginning of the tour and you are welcome to bring your own water bottle. There are no alcoholic beverages allowed at observing events.

The telescopes are open to the night air and it can get cold, so please dress accordingly.

What should I do when I arrive?

To enter the Observatory itself, walk the pathway from the lot to the south entrance. We’ll greet you at the doors about 10-15 minutes before your start time. Please arrive 10-15 minutes early to check in. Bring your email confirmation with you on your phone or printed.

What if I’m late and/or want to bring an unticketed friend?

To ensure the quality of the experience for all guests, late arrivals will not be admitted and will not be rescheduled or receive a refund. Space may not be available due to our maximum occupancy per tour. Online reservations are required. Other people with you may not enter the building and browse the exhibits or rooms. Everyone must have a reservation and time slot. Observatory staff members are the only people able to take visitors around the Observatory.

I can’t make it on my scheduled date. Is my ticket good for a future date?

No. An admission ticket purchased in advance shall become invalid upon the expiration of the time or period stated on the ticket. All ticket recipients must be present during purchase. Admission tickets cannot be transferred, refunded or exchanged. If you need to reschedule your night, please email us Monday through Friday during business hours at All sales are final.

What else should I be aware of?

The Gift Shop will be open at the end of your tour and is a card only service (no cash or check).

Because our construction and restoration is ongoing, Yerkes Observatory may restrict access to or close any of its property and cancel ticket reservations without advance notice, reason, cause, or explanation at any time.

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