Galileo's telescope In 1609, Galileo Galilei heard about the "Dutch perspective glasses" and within days had designed one of his own — without ever seeing one. He made some improvements — his creation could magnify objects 20 times — and presented his device to the Venetian Senate.

Galileo's Telescopes The basic tool that Galileo used was a crude refracting telescope. His initial version only magnified 8x but was soon refined to the 20x magnification he used for his observations for Sidereus nuncius. It had a convex objective lens and a concave eyepiece in a long tube.

While there is evidence that the principles of telescopes were known in the late 16th century, the first telescopes were created in the Netherlands in 1608. Spectacle makers Hans Lippershey & Zacharias Janssen and Jacob Metius independently created telescopes.

The Dutch telescopes magnified images by 3 times; Galileo's telescopes magnified them by 8 to 30 times. At the time, astronomy, like much of science, remained under the spell of Aristotle.