This was first really tested when Galileo got his hands on one of the first telescopes, and as he gazed into the night sky, what he found there was a planet, Jupiter, with four moons circling around it.
Isto foi testado pela primeira vez quando Galileu arranjou um dos seus primeiros telescópios e observou o céu noturno. Encontrou um planeta, Júpiter, com quatro luas, que giravam à volta dele.