Duke observatory offers open houses, hands-on access to the stars

A semi-circle rises out of a field in Duke Forest of Cornwallis Road. What looks like a bit like a small Stonehenge from the air is actually an observatory. The term “observatory” might bring to mind a rotating dome atop a building with a long, protruding telescope, but this one was designed with a different purpose in mind.

The observatory consists of nine piers equipped with outlets to power electronics as well as the heaters that keep telescope optics free from the dew that develops as temperatures change through the evening. Each pier was cast in a concrete cylinder extending underground to provide a steady base to mount the university’s five research-grade Schmidt-Cassegrain telescopes. This equipment helps fulfill the primary mission of the site by enabling multiple students to observe at once.

The Schmidt-Cassegrain telescope design combines the benefits of refracting (gathering light by passing it through lenses) and reflecting (gathering light by reflecting it with mirrors) telescopes into a compact package. Like refracting telescopes, light enters through a lens (Duke’s telescopes have a generous 10” wide aperture). Like reflecting telescopes, light is then gathered by mirrors and reflected to an eyepiece. Schmidt-Cassegrain telescopes are popular with researchers and astrophotographers because they fold that light path inside the tube, reducing the length of the tube and making the telescopes more portable.

The Duke Observatory hosts open house events every other Friday throughout the fall, weather permitting, from Sept. 11 through early December. Clouds are expected to decrease starting early Friday morning leading to partly cloudy skies and a slight chance of showers for the first open house of the season at 9 p.m.

Print out the directions on the website before going, the observatory can be a challenge to find. Also try entering the latitude and longitude of 36.015, -79.003 into your GPS.