Galileo Galilei

Chronicled events

1. 1610​·​Venus Shows Phases Like the Moon
   #5809

   Venus shows phases like the Moon’s, from nearly full to a thin crescent, and looks largest when it’s a crescent. In Ptolemy’s system, Venus always stays between the Earth and the Sun, so it could only ever show us a crescent.

   #5810

   Jupiter carries four moons around with it as it moves. So a moving Earth can keep its Moon, too.

2. 1632​·​Why We Don’t Feel the Earth Move
   #5811

   Everything on the Earth shares its motion, just as everything on a smoothly sailing ship shares the ship’s. A stone dropped from the top of the mast lands at its foot, and a cannonball keeps the Earth’s motion too, so it flies as far to the east as to the west. Equal distances show nothing about whether the Earth spins.