GALILEO'S TELESCOPE AT 400: Facts, Myths, More

James Owen in London
for National Geographic News
August 25, 2009

Galileo's telescope is today remembered as a revolutionary stargazing tool that changed Earth's standing in the heavens.

But when Italian mathematician Galileo Galilei presented his version of the telescope to officials in the Italian city-state of Venice, he was simply seeking a career boost, historians say.

Galileo needed a pay raise, in part to support several illegitimate children, said science historian Allan Chapman of the University of Oxford in the U.K.

"[He] was a rather obscure professor on the make showing a novelty invented by somebody else to his bosses," Chapman said.

Enemy Spotters

A math professor at the University of Padua, Galileo based his optical instrument on spyglasses developed the previous year by Dutch spectacle makers.

The Venetian Senate was about to purchase one of the popular gadgets when Galileo stepped in with his own version.

Made of wood and leather, Galileo's telescope had a convex main lens with a concave eyepiece like the original, Dutch-made telescopes, but his version boosted the viewing power to eight-times magnification.

(See a telescope time line.)

Venice's interest in the telescope was commercial rather than scientific, according to science historian Alan Chapman of the University of Oxford in the U.K.

The maritime city's wealth and power was based on overseas trade, and at the time its vessels were being attacked by the Turks, Chapman said.

To demonstrate the enemy-spotting potential of his telescope, "Galileo [took] a number of senators up to one of the bell towers in Venice where you can see ships out in the lagoon," he said.

Galileo Not the First Stargazer

In fact, Galileo's telescope was not even the first to gaze into the heavens.

That accolade goes to Englishman Thomas Harriot, who drew Earth's moon in July 1609, Chapman said.

But in 1609 most Europeans accepted the Roman Catholic Church's account of creation, which placed our planet at the center of the universe.

Galileo's telescope overturned this idea by allowing the scientist to observe moon-like phases in the planet Venus, which could only be explained by a sun-centered solar system.

Galileo likewise discovered that Jupiter was orbited by its own moons. (See telescopes' views of the universe.)

"This established beyond a doubt that the Earth was not the only center of motion in the universe," said Robert Massey of the Royal Astronomical Society in London.

Galileo's telescope and astronomical observations also showed the surface of the moon wasn't smooth, as was believed, and he was the first person to reveal that the Milky Way was composed of stars, Massey added.

According to Oxford's Chapman, the 400th anniversary of Galileo's telescope demonstration is only really relevant "in the context of what Galileo achieved later."

More Galileo's Telescope 400th Anniversary Coverage

TELESCOPE TIME LINE: From Galileo to Hubble
TELESCOPE HISTORY in National Geographic Magazine
GALILEO'S "DAUGHTERS": Today's Telescopes in Pictures
BLOG: Galileo's Telescope Helps Kick Off 100 Hours of Astronomy
PHOTOS: Telescope's-Eye Views of the Universe




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