400th Anniversary of Galileo's Telescope

Aug. 25, 2009 — -- Who invented the telescope? Not Galileo. Who first pointed it at the heavens? Again, it wasn't Galileo. So then why do we honor him today?

A number of the leading searches today on Google Trends include "galileo s inventions" (sic) and "who invented the telescope."

A fair amount of the interest, doubtless, was prompted by Google itself, which celebrated the "400th Anniversary of Galileo's Telescope" with a graphic on its homepage.

But there's some mythology at work here.

The first documented "spyglass" is generally credited to a Dutch lens grinder named Hans Lipperhey, who found that two lenses, properly placed, could magnify distant objects. He applied for a patent in 1608.

Likewise, an adventurous Englishman named Thomas Harriot (sometimes spelled Harriott) is generally given credit for reporting the first telescope observations of the moon. His first drawings, complete with craters and renditions of the Sea of Tranquility where Neil Armstrong would later walk, date to July 1609.

So what did Galileo do that is worth noting today? Nothing much. He just changed the world as western civilization knew it.

Sidereus Nuncius

In the summer of 1609 he showed off his first telescope (he did take credit for it), and began to look around the night sky with it. He mapped the moon, observed that the Milky Way must be made of individual stars, and saw "four planets never before seen" in orbit around Jupiter. He was looking at Jupiter's four largest moons -- Io, Europa, Ganymede and Callisto.

"Great indeed are the things which in this brief treatise I propose for observation and consideration by all students of nature," he wrote in "Sidereus Nuncius" ("The Starry Messenger"), his 1610 report on his findings.