ASTR 380 Study Guide - Quiz Guide: Star Formation, Edwin Hubble, Millisecond Pulsar

• School: University of Maryland
• Department: Astronomy
• Course: ASTR 380
• Professor: Husdon

Document Summary

*geocentric model: earth is at the orbital center. In the ptolemaic system, deferents were large circles centered on the earth, and epicycles were small circles whose centers moved around the circumferences of the deferents. The sun, moon, and planets moved around the circumference of their own epicycles. In the movable eccentric, there was one circle; this was centered on a point displaced from the earth, with the planet moving around the circumference. Retrograde motion: the apparent motion of a planet to move in a direction opposite to that of other bodies within its system (stars) (mars) Prograde motion: motion of a planet to move in a the same direction as the other bodies. *heliocentric model: sun is the center of the universe. Incorrect assumption that heavenly motion must occur in perfect circles. If earth moved, birds clouds would be left behind. 1: non-circular contradicts perfect unchanging view, no one detected stellar parallax that should occur if earth orbits sun.