In recognition of the importance of preservation efforts, this periodic series features historic buildings on the UI campus.
A little more than a decade after it was built 100 years ago, the UI
Observatory became the site of a scientific development considered revolutionary
in its day.
Joel Stebbins, a professor at the UI, helped to develop a system to measure the brightness of stars at the UI Observatory. He worked with an instructor, F.C. Brown, to create a selenium cell to use in a photometer. While it took time to perfect the selenium photometer, they used their innovation to discover three double stars, construct a light curve for the moon, determine the time of mid-eclipse during the July 24, 1907, lunar eclipse and measure the magnitude of Halley's Comet in May 1910.
It was Stebbins who convinced the UI Board of Trustees to establish an astronomy department in 1905, just nine years after the observatory was built.
In the spring of 1895, the UI was given $15,000 by the legislature - at the request of the trustees - to build the Astronomical Observatory and equip it. It took another two years to complete that task.
The equipment cost $8,340 - which included 12-inch and 4-inch equatorial telescopes, 3-inch and 2-inch combined transit and zenith telescopes, a good chronograph and a cheap chronograph. The building and dome cost $6,680.
Historically, the observatory is considered an unusual structure. It was built of repressed brick; its entrance faces north. The interior rotation system is historically significant. When it was built, the dome was described as revolving on trucks that rolled on a circular rail and was turned by hand using a rope and sheave.
But it was the work done by Stebbins and Brown that played a key role in the observatory being named a National Historic Landmark by the U.S. Department of the Interior in 1990.