The semi-major axis, a, of an elliptical planetary orbit is equal to the
A) width of the ellipse
B) distance between the planet and the Sun at perihelion
C) average distance between the planet and the Sun
D) distance between the planets and the Sun at aphelion

Question

Quizplus · Accepted Answer

The semi-major axis (a) is defined as half of the longest diameter of an ellipse. In the case of an elliptical planetary orbit, the semi-major axis represents the average distance between the planet and the Sun. Therefore, the correct choice is C.

The Semi-Major Axis, A, of an Elliptical Planetary Orbit Is