Astronomy 1021 Lecture Notes - Lecture 5: Nicolaus Copernicus, Celestial Pole, Universal Law

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Robert Cockcroft

Document Summary

Aristotle: geocentrism (stuck with this until the scientific revolution. Pu(cid:271)lished (cid:862)o(cid:374) the re(cid:448)olutio(cid:374) of the hea(cid:448)e(cid:374)ly phe(cid:396)es(cid:863) Mercury and venus close to sun. Tycho brahe: 30 years of naked-eye accuracy, parallax, no(cid:448)a (cid:894)(cid:862)(cid:374)e(cid:449) sta(cid:396)(cid:863)(cid:895) i(cid:374) (cid:1005)57(cid:1006, comet, both much further than moon, against core aristotelian/ptolemaic system. Nearby objects have a larger parallax than more distant objects. Sun is at one focus of the eclipse. Sun-planet line sweeps out equal areas during equal intervals of time (planets move faster in thei(cid:396) o(cid:396)(cid:271)its (cid:449)he(cid:374) they"(cid:396)e (cid:272)lose(cid:396) to the u(cid:374)(cid:895) Planet moves faster when closer, and slower when f=urther. More distant planets orbit the sun at slower average speeds. Planets obey the precise mathematical relationship: p^2 = a^3. P is the planet"s o(cid:396)(cid:271)ital pe(cid:396)iod i(cid:374) years. A is the average distance from the sun in au. Proto-planet is unlikely to have exact position and exact velocity to land in a perfectly circular orbit.