This is another anniversary that I did not know about in advance. A day late is better than two days late, right? Unfortunately, I cannot write later today as I have a date with my dentist. Not a fun date, either. So the verbatim posting from Slashdot will have to do:
OK, the moons themselves are much older, 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.
Four hundred years. Where does the time go?!