HUT Observatory

Education with the World’s Largest Refractor

Nate and Ike Janssen open the shutters to the 90-foot Yerkes Observatory dome.

Visiting students Nate and Ike Janssen open the shutters of the 90-foot Yerkes Observatory dome during an open house September 20, 2013.

In September, 2013, two events at the University of Chicago’s Yerkes Observatory brought crowds of especially excited visitors to see and use the world’s largest refracting telescope.  The result confirmed that nothing beats actual experience when learning something new and interesting.

With an aperture of 40 inches and a tube 63 feet long, the mammoth Yerkes instrument was constructed over a century ago in a combined effort by lens makers Alvan Clark & Sons and machine builders Warner & Swasey.  Visitors where able to see through the historic instrument and even operate it by hand, its motion being like the great momentum of a bank vault door.

J. W. Briggs from HUT Observatory introduces the Yerkes 40-inch refractor to visiting students.

J. W. Briggs from HUT Observatory introduces the Yerkes 40-inch refractor with the room’s elevating floor in an intermediate position.

On September 16, the Antique Telescope Society returned to Yerkes as part of its 22nd annual convention.  The group enjoyed afternoon lectures by Yerkes staff and an observatory tour.  The highlight, however, was an evening observing session with the 40-inch.  The activities were organized by HUT astronomer J. W. Briggs, who was a staff engineer at Yerkes through the 1990s and is a past president of the Society.  While the largest modern telescopes are robotic machines typically operating in an industrial mode, the Yerkes refractor remains hands-on.  Experiencing it is unforgettable.  Targets included the Moon and globular star cluster Messier 15.

The Janssen family, among visitors to Yerkes Observatory in September, 2013, explore the 40-inch telescope.

The Janssen family, among visitors to Yerkes Observatory in September, 2013, explore the 40-inch telescope.

The following Friday evening, the Observatory organized a special event highlighting its new FabLab, a fabrication laboratory for students featuring 3-dimensional printing technology.  The FabLab is part of the Observatory’s expanding mission as an outreach and education center for science and technology.  Among the visitors to this event was the Janssen family from Peru, Illinois.  Mr. Peter Janssen is presently refurbishing an observatory built by his grandfather, and he supplied the photos reproduced here of his sons exploring the 40-inch.  He wrote, “It is rare that we do something that I wish my Grandfather could have been a part of, but our evening at Yerkes made me think just that.  From Nate and Ike opening the shutter, to the momentum of the scope lifting Nate off the floor; he would have enjoyed it all.”