Jupiter quite obviously had its own moons; this was devastating to the Catholic church's long-held views, but did not, per se, prove Copernicus' theory.
It was the phases of Venus that confirmed the Copernicus model. The only explanation for Venus' phases is that it was orbiting the sun, and its orbit is INSIDE the earth's. This was the real nail-in-the-coffin for Aristotle's and the Church's geocentric explanation.
