Principe 3

sky tonight

why would people be interested in the night sky? what would they look for?

What were the predominant theories of astronomy before the scientific revolution?

Aristotle (ancient Greece, 4th century BCE) saw the earth (everything below the moon) and the superlunar world as completely different

ptolemaic system
Copernicus (1473-1543) thought the system was too messy
retrograde motion

Tycho Brahe (1546 – 1601) was shocked to see a new star (the heavens were supposed to be unchanging, comets were understood to be below the moon)

Brahe hired Johannes Kepler (1571-1630) to work with his data

Galileo Galilei (1564-1642)

phases of venus
But no one had yet worked out a physics to explain the Copernican theory