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.

Some of humanity's modern telescopes look nothing like their predecessors, but they share a common purpose and history. Here's how mankind learned to see the stars. Read more: 14 Best Fighter ...

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 mentions that “On the 7th day of January in the present year, 1610, in the first hour of the following night, when I was viewing the constellations of the heavons through a telescope ...

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 ...