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Watching the stars with the eye of Galileo
PHILADELPHIA: It looked like the kind of toy telescope a child might have made with scissors and tape — a lumpy, mottled tube about as long as a golf club and barely wider in girth, the color of 400-year-old cardboard.
But near one knobby end was a bit of writing that sent Derrick Pitts, chief astronomer of the Franklin Institute here, into rapture.
The tube's focal length is "piedi 3," the inscription said, or 3 feet. It was in the hand of Galileo, one of history's great troublemakers. "Absolutely amazing," Mr. Pitts said.
Thus did Galileo Galilei, the astronomer and mathematician, come to America.
By turning spyglasses like this to the sky 400 years ago and seeing mountains on the moon and satellites whirling around Jupiter in contravention of the Earth-centered cosmology of Aristotle and Ptolemy that had reigned for a thousand years, Galileo overturned the world.
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Only two of the dozens of telescopes Galileo built in his lifetime survive. Neither of them have ever been out of Florence since Galileo's time, until this week, when Giorgio Strano, curator at the Instituto e Museo Nazionale di Storia della Scienza, escorted this humble tube to the Franklin Institute.
Scholars do not know when Galileo built this particular telescope, or what he saw with it, but it still has its original optics.
A brief handling of the instrument — with gloved hands and under the stern gaze of Mr. Strano — gives you an idea of how hard it must have been for Galileo to be Galileo. Squinting through the eyepiece, the field of view is so narrow that it explains why even he failed to discover the Orion Nebula.
Galileo began to build telescopes, gradually increasing in magnification, in the autumn of 1609 after hearing that a Dutch spectacles maker, Hans Lipperhey, had built a spyglass.
He made his first observations, of the moon perhaps, in October, said Owen Gingerich, a historian of astronomy at Harvard.
But what Galileo did with his homemade spyglasses cast long shadows. His discoveries propelled astronomers on a course toward discovering signs of the Big Bang and a strange modern cosmos suffused with dark energy and dark matter. The Galileo affair, as historians call it, was the template for the war between science and religion that persists to this day.
The telescope will be the centerpiece of "Galileo, the Medici and the Age of Astronomy," which opens April 4 at the Franklin Institute. The show runs until September.
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