Ordering the night sky is a past time enjoyed by humans all over the world and throughout history. People have noticed the shifting lights as they reel over head, and some were even clever enough to note that a few of them moved contrary to the rest.
These “planetes asteres”, (that’s Greek for “wandering stars), were seen as emissaries of the gods or they held portents of the future.
When Galileo Galilei used his telescope to view our solar system’s 5th planet from the sun and neighborhood giant, Jupiter, he found more than a messenger.
What we witnessed was a series of objects orbiting Jupiter, its moons. This flew in the face of conventional wisdom which said that all stellar objects orbited around earth.
From this evidence and more that he would collect in the future, Galileo formed his idea of a heliocentric, or sun-centered solar system we observe today.