Last Tuesday, August 25, was the 400th anniversary of Galileo's telescope, and [as is their custom] Google celebrated with a custom logo, shown at left, one of their best.

Galileo didn't invent the telescope - that would be Hans Lippershy - but he made it famous by doing something literally heretical: pointing it at the stars.  Prior "spyglasses" had been used primarily for spying on girls enemy warships, but Galileo looked our moon and discovered it had features (gasp!), it was not a perfect unmarked sphere.  That was pretty bad...  but later he found four moons orbiting Jupiter (gasp!) instead of Earth, and then Saturn's rings...  the totality of his observations convinced him the Copernican theory that planets orbited the Sun instead of Earth was correct.