Telescopic discoveries
- Milky Way not continuous like “smoke”
- Telescope resolved it into millions of stars
- 4 Galilean satellites of Jupiter
- aligned along the Ecliptic
- motion implied orbits around Jupiter
- proof that there was more than one center of motion
- made sense that our Moon could orbit us while we orbit the Sun (i.e.. Copernicus)
- Venus went through full set of phases (like Moon)
- therefore Venus orbited the Sun
- demo -- ball=Venus, teach=Sun, students=Earth
- blackboard -- Greek epicycles vs. Copernican orbit
- 61” (max size, crescent) vs. 10” (min, full) => distance ratio 6.1 to 1(Small Angle Formula).
- Moon sets ~ 2 h after Sun rose today -- what is it’s phase?
- can tell Earth is rotating with Focault pendulum