Astronomy

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Dan Koehler (left), director of tours and special programs at Yerkes, chats
with the author about the history of the facility. In the background looms
the famous 40-inch refractor — the world’s largest lens-type telescope.
The telescope weighs 82 tons with a tube 64 feet long (19.5 meters).
The entire assembly rises above the basement level by 65 feet (19.8 m).
MICHAEL E. BAKICH

Astronomer Wayne Osborn explains some of the records of observations
made by American astronomer Edward Emerson Barnard during the time
he spent at Yerkes Observatory. MICHAEL E. BAKICH

Another of the telescopes at Yerkes with a high usage curve is the 24-inch

reflector. Groups use it, as well as the 40-inch refractor, most clear nights

of the year. COURTESY OF YERKES OBSERVATORY

Among the many historical settings at Yerkes is the office of Subrahmanyan

Chandrasekhar, who began working at the University of Chicago in 1937. It

is currently occupied by Jim Gee, the observatory’s director of operations.

DAVID J. EICHER

This blink comparator dates to 1905. Astronomers at Yerkes used it to
discover high proper motion stars, variable stars, and other changing
celestial phenomena. DAVID J. EICHER