By Studying the Orbit of a Moon Around Its Parent

Multiple Choice

By studying the orbit of a moon around its parent planet, astronomers can use ________ to find the parent planet's ________.

A) escape velocity; rotation rate
B) the moon's eccentricity; Roche limit
C) small perturbations; magnetic field strength
D) the moon's velocity; radius
E) Newton's version of Kepler's third law; mass