Today, we look through some really big telescopes.
The University of Houston's College of Engineering
presents this series about the machines that make
our civilization run, and the people whose
ingenuity created them.
The astronomer George Ellery
Hale was born just after the Civil War. In 1892, as
a 24-year-old professor at the University of
Chicago, he organized the Yerkes Observatory.. There he
built the largest telescope ever to use a
conventional refractor lens. It was over three feet
in diameter. But it was also doomed to become a
dinosaur within a few years, because astronomers
gave up conventional lenses in favor of focused
mirrors after 1900.
Hale, however, was no dinosaur. By 1904 he'd
convinced Andrew Carnegie to give him a hundred and
fifty thousand dollars to set up the Mount Wilson
observatory in California. Hale was downright
greedy for high resolution, and straightaway he
developed the largest mirror telescope ever built.
It was five feet in
diameter.
At first he joyfully cried, With this we'll
record ... a billion stars! But 1918 found him
back at Carnegie's doorstep asking for money to
build a new mirror more than eight feet in
diameter. Visit the quiet site along the Mount Wilson rim today and
you'll see that telescope, along with the five-foot
one, still in use.
Hale was now only fifty, but his health had begun
to fail him. He had to retreat from fieldwork in
astronomy. But that didn't stop him from planning,
writing, and organizing. In 1916 he'd founded the
National Research Council, and he was now deeply
involved in the task of setting America's
scientific research agenda.
But one more telescope was on Hale's agenda -- a
really big one this time. Andrew Carnegie was dead
by now, but the Rockefellers gave Hale six million
dollars for a third mirror -- one almost seventeen
feet in diameter. That mirror was to become the
heart of the Mount Palomar Observatory, also in
California.
In 1934, the Corning Glass Company tried to make
the first rough casting of this seventeen-foot
mirror. They cooked a fifty-foot lake of molten
glass for six days at 2700°F. When they poured
it, with the press watching, the inside of the mold
broke up. Nine months later they tried again and
succeeded. It took eight more months to cool it
down. And grinding it by hand to within a millionth
of an inch took years. The story has it that the
man who did that job on the eight-foot mirror ended
in a mental institution.
Hale died in 1938, and the Mount Palomar telescope
was finally finished ten years later. Until the
Russians made a larger one in 1986, it remained the
world's grandest optical telescope. Compare its
five hundred foot effective focal length
(ninety-one inch actual) with the eight-inch focal
length of your long-distance zoom lens. It finally
took the new radio telescope to improve on its
resolution.
We have to be moved by Hale's unmatched vision,
nerve, and determination. Just think: over a
56-year period, from the age of 24 until ten years
after his death, George Ellery Hale gave us the
world's largest telescope not once, but four
times.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
