A comet orbits the Sun with a semimajor axis of 90 AU.Using Kepler's third law, the comet's orbital period is approximately
A) 850 years.
B) 630 years.
C) 410 years.
D) 180 years.
E) 90 years.

Question

Quizplus · Accepted Answer

According to Kepler's third law, the square of the orbital period (T) is proportional to the cube of the semimajor axis (a) of its orbit. For a semimajor axis of 90 AU, T^2 = 90^3. Solving for T gives approximately 850 years.

A Comet Orbits the Sun with a Semimajor Axis of 90