AST 307 · Introductory Astronomy

Fall 2003

Topics
Chapter 2 Sep. 510
 Describe the motions of the planets on the celestial sphere,
and use the Copernican (heliocentric) model to explain their
prograde and retrograde motions.
 State Kepler's three laws of planetary motion.
 Define: aphelion, perihelion, semimajor axis.
 Be able to use Kepler's 2nd law to compare the speed of a planet
at perihelion to its speed at aphelion.
 State Newton's three laws of motion and his law of gravity.
 If a planet orbits the Sun on a circular orbit:
does its speed change?
is it accelerating?
what force or forces are acting on it and in what direction?
how does the force it exerts on the Sun compare to the force the
Sun exerts on it?
 Explain how Newton's laws can be used to derive Kepler's 3rd law
and how the result differs from Kepler's law.
 Describe the concepts of kinetic and potential energy and describe
how they can be used to calcuate the escape speed from a planet.
