ISP 205 Lecture Notes - Lecture 5: Ellipse, Orbital Period
Document Summary
Tycho"s observations: measured positions of the planets for about 20 years, very accurate, very reliable, measured and compensated for instrument flexure, the biggest error. Kepler"s 3 laws, very important: newton"s generalization of kepler"s 3rd law is used to measure mass, kepler"s laws have historically been the keys to deciphering motion. Kepler"s first law: the orbit of each planet around the sun is an ellipse with the sun at one focus: point of closest approach to the sun: perihelion, farthest point: aphelion. Kepler"s second law: as a planet moves around its orbit, it sweeps out equal areas in equal times farther from the sun: planet travels faster when it"s nearer to the sun and slower when it is.