A comet in a highly elliptical orbit is found to have a semimajor axis equal to one astronomical unit (AU). According to Kepler's 3rd law, what would be the sidereal period of this comet
A)more than one year
B)one year
C)less than one year
D)76 years; the same for every comet
E)Not enough information is given to determine this.

Question

Quizplus · Accepted Answer

Kepler's 3rd law states that the square of the orbital period of a planet (or comet) is directly proportional to the cube of the semi-major axis of its orbit. Since the semi-major axis of the comet is given as one astronomical unit (AU), which is the average distance from the Earth to the Sun, its orbital period would be the same as Earth's, which is one year.

A Comet in a Highly Elliptical Orbit Is Found to Have