399 years ago today, Galileo Galilei was looking through his telescope when he took note of two starry objects next to Jupiter. The next night, he noticed that they moved strangely, so he kept his lens trained on the giant planet for several days. He saw that there were actually four of these bodies in motion, and came to the realization that they were orbiting around Jupiter.
This was humanity’s most compelling evidence that Copernicus was right. Jupiter does not revolve around us. The sun does not revolve around us. The universe does not revolve around us. I’m not sure that we’re grounded in these facts yet, nearly 400 years later.
You can’t mark this occasion by looking at Jupiter tonight, unless you live on the other side of the sun. But the moon will be crossing the Pleiades at sunset, which, my son informed me last night, is my “favorite cluster.” Then he had plastic mommy drive plastic him in a plastic car to “the observatory” to look through telescopes.
The Galilean moons of Jupiter (pictured): Io, Europa, Ganymede, Callisto.
P.S. These moons are not finished messing with our overdeveloped sense of importance yet. There is evidence of saltwater on three of them, and of large oceans on Europa. That could mean life off of our planet in our own solar system. Read more.