The journey of astronomical telescopes began in the early 17th century when Galileo Galilei crafted his first refracting ...

The first spectacles, designed to correct farsightedness ... "objective" lens—the convex lens at the far end of the telescope—Galileo ground a lens larger than he needed, for example.

Second, you soon want a bigger telescope. Galileo, who first trained a telescope on the night sky 400 years ago this fall, pioneered this two-step program. First, he marveled at what he could see.

Galileo Galilei's telescopic discovery of Jupiter's four moons in 1610 revolutionized astronomy and supported heliocentric ...

Still, even Galileo recognized the ground-based uses of telescopes. After building his first telescopes, Galileo demonstrated the new instrument to the Venetian Senate, including military leaders.

Galileo made himself one of the world's first telescopes and discovered the moons of Jupiter. He supported Copernicus' theory that the Earth revolved around the Sun. This brought him in conflict ...