AST101H1 Chapter Notes - Chapter 3: Ellipse, Orbital Period, Semi-Major And Semi-Minor Axes

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Michael Reid

Document Summary

Free-fall: object moving under influence of gravity alone. Vorbital = min. speed to orbit, barely misses earth. Vorbital < velliptical < vcircular < velliptical < vescape. Vescape = leaves orbit [does not depend on mass] Tycho brahe: first-ever accurate and complete charts of the motion of planets. Johanes kepler: 3 laws of planetary motion. Eccentricity: how much an ellipse is stretched out [c/a] Orbit of each planet around the sun is an ellipse with the sun at one focus. Second law: cover equal areas in equal time. Perihelion: closer to focus travels faster. Aphelion: farther from focus travels slower. Third law: p2 = a3 (objects in wider orbits take longer to orbit) Orbital period (p): time it takes a planet to orbit the sun.