Forget Space Travel: Build This Telescope

The first telescopes were toys, charming amusements. Sure, there were a few practical uses, such as observing distant ships coming into harbor. Doing so allowed merchants to hurry down to the docks ahead of their telescope-free competitors, and snag all the better goods. Military commanders occasionally found telescopes handy as well. And when they weren't being used for commerce or conflict, these simple devices were undoubtedly helpful for checking out the personal parameters of careless neighbors.

In 1609, Galileo turned a telescope skyward -- a move that no one else seems to have considered. His instruments had lenses about the size of a half-dollar coin, and magnifications that were only about 20 times. Their simple optics had more aberrations than Vlad the Impaler.

Today, you wouldn't give a kid a telescope this lousy, unless you're inspiring her to forsake science in favor of a more lucrative occupation, like starching shirts. But these low-grade constructions were good enough to see the bigger moons of Jupiter, the craters of the moon, and stars making up the Milky Way. They were, despite their pitiful specifications, arguably the most important astronomical telescopes of all time.

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