As commemorated by the International Year of Astronomy and observed elsewhere on this site, 2009 marks the 400th anniversary of the year that astronomer Galileo Galilei began fashioning his own telescopes and turning them to the heavens. Before long, he started to characterize the surface of the moon, discovered a quartet of Jupiter's moons, and began to revolutionize our view of Earth's place in the universe.

Four hundred years ago this week, Galileo reached a milestone along this journey, presenting his telescope to the Senate in Venice on August 25, 1609. The senators were duly impressed, according to historical accounts, doubling the astronomer's salary and making his university appointment a lifelong one.

Prior to August 1609, as noted by contributor Saswato R. Das in a New York Times op-ed, others had already tried to patent the telescope and others still had, arguably, beat Galileo to the punch in using such a device to study the moon in detail. But it was the Italian professor of physics and mathematics who brought it to the mainstream, publishing a suite of landmark observations in 1610.

For a look at Galileo's telescope and nine others that changed astronomy forever, see our recent slide show undertaken in honor of historic anniversary.

Portrait of Galileo: Wikimedia Commons