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)It depends on the eccentricity of the orbit, as described by Kepler's first law.
B)Each orbit takes about 1 year, which we know from Kepler's third law.
C)Each orbit should take about 2 years, because the eccentricity is so large.
D)It depends on the eccentricity of the orbit, as described by Kepler's second law.

Question

Quizplus · Accepted Answer

Kepler's third law states that the square of a planet's orbital period is proportional to the cube of its average distance from the Sun. Since the comet has an average distance of 1 AU, which is the same as Earth's distance from the Sun, it takes about 1 year (or 365.25 days) to complete one orbit around the Sun. The eccentricity of the orbit does not affect the orbital period, only the shape of the orbit.

Suppose a Comet Orbits the Sun on a Highly Eccentric