Suppose a comet orbits the Sun on a highly eccentric orbit with an average (semimajor axis) distance of 1 AU. How long does it take to complete each orbit, and how do we know?
A) Each orbit takes about 1 year, which we know from Kepler's third law.
B) It depends on the eccentricity of the orbit, as described by Kepler's second law.
C) It depends on the eccentricity of the orbit, as described by Kepler's first law.
D) Each orbit should take about 2 years, because the eccentricity is so large.

Question

Quizplus · Accepted Answer

Kepler's third law states that the square of the period of an orbit is proportional to the cube of the semimajor axis. Since the average distance of the comet's orbit is 1 AU, the period of the orbit should be about 1 year (365.25 days).

Suppose a Comet Orbits the Sun on a Highly Eccentric