Galileo did not invent the telescope, but on hearing, in 1609, that such an optical instrument had been made, he quickly built his own device from an organ pipe and spectacle lenses.

Early telescopes developed by Galileo and Newton are featured, along with modern space telescopes.

Galileo's greatest glory was that in 1609 he was the first person to turn the newly-invented telescope on the heavens to prove that the planets revolve around the sun rather than around the earth.