A comet is observed to return to the vicinity of the Sun on a long elliptical orbit with a period of 31.7 years. What is the semimajor axis of the orbit?
A) 31.7 au
B) 178.5 au
C) 10 au
D) 1000 au

Question

Quizplus · Accepted Answer

According to Kepler's Third Law, the square of the orbital period (in years) is proportional to the cube of the semimajor axis (in astronomical units, au). For a period of 31.7 years, the semimajor axis is approximately 10 au.

A Comet Is Observed to Return to the Vicinity of the Sun