Archaeologica.org

OK, the moons themselves are much older of course, but on January 7, 1610 Galileo first observed '4 fixed stars' surrounding Jupiter. Observations of their changing positions led Galileo to postulate they were really moons orbiting Jupiter, which became further evidence against Aristotelian Cosmology, which led to problems with the Roman Catholic Church, etc...

Jupiter will be low in the southwest (in the Northern Hemisphere) after sunset this evening — nothing else around it is as bright, so you can't miss it. Celebrate by pointing binoculars or a telescope at Jupiter and checking out the moons for yourself.

http://en.wikipedia.org/wiki/Galilean_moons

And for that they wanted to burn him at the stake!

But instead, humanely, they 'only' effectively excommunicated, ostracized and confined him for 20 years...

Leniency.

Too many bleeding heart judges.