A giant nineteenth-century orrery that mechanically reproduces the motions of the inner solar system can be found at the Center for Kentucky History in Frankfort, Kentucky. The orrery—also known as a planetarium—was created to be a teaching tool by Thomas Barlow (1791-1865) of Lexington, Kentucky, with his son Milton. However, it is also a work of astronomical art!

I actually learned about the Barlow from Jamie Day, a professor of physics at Transylvania University in Lexington. He gave a talk on it at a conference at the University of Notre Dame in July of 2017.* This is the second grand-scale piece of astronomical art in Frankfort, Kentucky that I have featured in the Astronomy in Art and Architecture series (click here for the whole series)—the other being the Kentucky Vietnam Veterans Memorial. Thus Frankfort, Kentucky’s Capital, is definitely worth a visit if you are interested in astronomy.

*The title and abstract of Prof. Day's talk at the University of Notre Dame:

“The History and Conservation of the Barlow Planetarium”

Abstract: In the mid-1800s, Thomas Harris Barlow—an agricultural industrialist and mechanical savant—designed an intricate and expansive mechanical model of the inner solar system. Barlow collaborated with James Dodd—mathematician and president of Transylvania University—to calculate the gearing, and labored for over a decade before arriving at his final design: a thirteen-foot diameter mechanism of wood, glass, filigreed cast iron, and precision gears. For nearly fifty years Barlow and his son, Milton, manufactured and marketed the planetarium, which was met with great acclaim. Unfortunately, the enormous stresses inherent in such a large instrument frequently led to mechanical failure. Recently, two examples have been beautiful conserved and returned to exhibit, and restoration of a third planetarium is underway. This talk will review the history of Barlow’s planetarium and the current state of the models that survive.