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.

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.