AST101H1 Lecture 5: Heliocentric Universe

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Bryan Gaensler

Document Summary

Before copernicus: stars, sun, and moon rise and set every day. It does(cid:374)"t feel like the earth is (cid:373)o(cid:448)i(cid:374)g: the stars do(cid:374)"t see(cid:373) to e(cid:448)er (cid:272)ha(cid:374)ge, things fall to earth, the heavens are perfect and incorruptible, circles are perfect. Therefore: the earth is the center of the universe, everything revolves in circles around it, planets move in circles within circles. Tycho brahe: makes extremely precise measurements of the motion of mars, used parallax to constrain distances. Johannes kepler: worked fro(cid:373) ty(cid:272)ho brahe"s data, was concerned with the inaccuracy of the models of his time for theological reasons. Kepler"s (cid:1005)st law planets orbit the sun in an elliptical pattern, with the sun at one focus. Kepler"s (cid:1006)nd law planets trace out equal area in equal time. Kepler"s (cid:1007)rd law more distant planets orbit slower. Galileo galilei: used a telescope to look at the sky, showed that jupiter has moons. Therefore, not everything orbits the earth: showed that the moon has craters.