Astronomy

AFTER A FULL MORNING expe-
riencing Fermilab, we headed north,
back into Wisconsin, winding our way
through country highways. A 90-minute
drive brought us to the town of Williams
Bay on picturesque Lake Geneva, home
of one of the great historic astronomy
research centers in the United States:
Ye r k e s O b s e r v a t o r y.
There, we met with Dan Koehler, the
observatory’s director of tours and special
programs. He gave us an incredible
behind-the-scenes tour. We started with
the famous 40-inch Alvan Clark refractor,
the largest refracting telescope ever built,
and we discussed at length the role of
Yerkes, which commenced in 1897.
The observatory’s founder, George
Ellery Hale, went on to California to create
Mount Wilson Observatory, and he became
the driving force behind the Palomar
200-inch scope. So in a sense, much of the
era of American astrophysics originated at
Yerkes. It was certainly a thrill to stand on
the f loor of the big dome, right where
Albert Einstein famously posed with the
Yerkes staff back in 1921. We also got a
great insider look at the observatory’s
24-inch ref lector.
Treasures awaited us inside the observa-
tory’s hallowed hallways, too. Dan showed
us the office used by the legendary
Subrahmanyan Chandrasekhar, the Nobel
Prize-winning physicist who spent much of
his career at the University of Chicago and
at Yerkes. Additionally, Wayne “Ozzie”
Osborn gave us an extensive tour of Yerkes’
glass photographic plates.
From the collection of 180,000 plates,

Ozzie showed us images from the 40-inch

refractor, cometary plates, tiny spectra

used to measure stellar motions, an eclipse

photograph that proved Einstein’s general

theory of relativity, and records of photo-

graphs taken and kept by Edward Emerson

Barnard and many others. Ozzie also

showed us amazing artifacts. We saw the

lunar sphere used by Gerard Kuiper to

project craters so that astronauts could

train for lunar landings. We saw a rare

blink comparator from 1905, like the one

used to discover Pluto and Barnard’s Star.

And we saw the spectrograph used on the

40-inch scope by William W. Morgan to

classify stars, as well as the filar microm-

eter used in the early history of Yerkes to

make precise double star measurements.

Share our experience

Our trip to Chicago was unlike any we had

taken before. Visiting some of the region’s

brilliant astronomers and seeing hidden

artifacts and some of the great instruments

and displays of astronomy in the Midwest,

we were spellbound.

Michael and I took turns filming this

whole experience, and we captured three

hours of amazing footage that provide a

“backstage pass” to astronomy and space

science in and around Chicago. In fact, we

have created a DVD that contains the

entire experience, showing all that I have

described in this story and much more.

(See “Your own private tour” on p. 49 for

information on how to get your own copy.)

Our hats are off to the accommodating

staffs of Adler Planetarium, the Field

Museum, Fermilab, and Yerkes

Observatory. What a window into the past,

present, and future of our knowledge of the

universe they have given us.

The world’s largest glass

YERKES

OBSERVATORY

Astronomy Editor David J. Eicher is a longtime

fan of everything in Chicago (except the Bears).

Astronomy Senior Editor Michael E. Bakich

stands near the 40-inch refractor at Yerkes

Observatory. As this image was being shot,

he was riding the motorized floor in the

observatory. The floor weighs 38 tons and

is rated for 26 passengers. DAVID J. EICHER

The plate vault at Yerkes contains the

photographs taken on glass plates since the

40-inch telescope began operating in 1897.

The collection is one of the finest on Earth.

MICHAEL E. BAKICH

Yerkes Observatory, founded in 1897 by

American astronomer George Ellery Hale,

stands near Lake Geneva in Williams Bay,

Wisconsin. The University

of Chicago Department

of Astronomy and

Astrophysics operates it.

COURTESY OF YERKES OBSERVATORY