On our way south from Michigan we stopped in Twin Lakes, Wisconsin to visit our friends Jeff & Mary Pat. We needed to kill some time one afternoon when we remembered that we had previously tried to visit the Yerkes Observatory in nearby Williams Bay.

We tried to visit the observatory in October 2019 (Blog Post) but discovered that it had been closed and was not permitting visitors. We talked at length with the caretaker, who had been outside mowing the lawn. He explained that the observatory was in the process of being transferred to a private foundation and the goal was to re-open to the public sometime in the coming years.

We were pleased to discover that the observatory in now in the hands of The Yerkes Future Foundation. It remains a working observatory, and the only way to visit is by booking a tour, so that’s what we did.

Yerkes Observatory has a long history of discovery and has been visited by famous scientists and astronomers over the years, including Albert Einstein, Edwin Hubble, Nancy Grace Roman, Gerard Kuiper, Mary Calvert, E.E. Barnard, Richard Kron, Carl Sagan and many more. The Yerkes 40-inch Great Refractor Telescope was the largest refracting-type telescope in the world when it was dedicated in 1897 (40 inches refers to the size of the main lens element). The telescope is 63 feet long, weighs 12,000 pounds and is so delicately balanced that it can be moved by hand.

The library/storage area contains hundreds of books on astronomy and astrophysics, along with an interesting array of old equipment, including cameras and enlargers. We even got to see some old slides that were made before digital imaging became the standard.

The foundation has done a beautiful job restoring the facility and does a nice tour. We even got to see the dome rotated and the floor raised, which is one of the way to access the eyepiece of the telescope!