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The `revolution' described in this week's lecture is a revolution of ideas. Copernicus started the revolution by recognizing the Earth as one of several similar planets, but he still used laws of planetary motion different from the laws applicable to motion on Earth. Newton completed the revolution by showing that planetary motion and terrestrial motion obey exactly the same laws. Between these two are Kepler, who wrote down the first correct laws of planetary motion, and Galileo, who found observational evidence for the Copernican system and clarified the nature of motion on Earth.
Topics:
Reading:
| Ch. 3-1 | Copernicus devised the first comprehensive heliocentric cosmology |
| Ch. 3-2 | Tycho Brahe made astronomical observations that disproved ancient ideas about the heavens |
| Ch. 3 | KEPLER'S AND NEWTON'S LAWS (p. 60) |
| Ch. 3-3 | Kepler's laws describe orbital shapes, changing speeds, and the lengths of planetary years |
| Ch. 3-4 | Galileo's discoveries strongly supported a heliocentric cosmology |
| Ch. 3-5 | Newton formulated three laws that describe fundamental properties of physical reality |
| Ch. 3-6 | Newton's description of gravity accounts for Kepler's laws |
| Ch. 4-8 | Gravitational forces produce the tides and keep the same side of the Moon always facing the Earth |
Web Resources:
Interactive model of the Solar System, created by John Walker.
Shows the retrograde motion of Mars between 01/01/99 and 08/29/99.
Interactive simulation of retrograde motion, created by Rob Scharein at UBC.
Home experiments with gravity, by John Walker. See a version of the Cavendish experiment (as Archimedes might have done it, if he'd had the idea) in action or slower-motion.
Further Reading: Not part of this course, but highly recommended summer reading:
Homework 4: Planetary Positions, due 9/25.
Quiz 4: Kepler's Laws, given 9/20.
Last modified: September 21, 2001
http://www.ifa.hawaii.edu/~barnes/ast110/rots.html
