Evolution and Differentiation of Large Icy Moons
In the early 17th century when Galileo Galilei first decided to point a telescope at Jupiter, he noticed four faint objects placed around it on the same line. As he spent more and more nights viewing them he realised that instead of moving in the same direction as Jupiter these four objects in fact orbited the planet itself. This proved that it is possible for another body to be the centre of grav
