The center of mass of the Earth-moon system
A) lies beneath Earth's surface on a line that joins the centers of Earth and the moon.
B) describes the true orbit of the Earth-moon system about the sun.
C) is between Earth and the moon on the line through their centers.
D) lies beneath Earth's surface on a line that joins the centers of Earth and the moon and describes the true orbit of the Earth-moon system about the sun.
E) lies beneath Earth's surface on a line that joins the centers of Earth and the moon, describes the true orbit of the Earth-moon system about the sun, and is between Earth and the moon on the line through their centers.

Question

Quizplus · Accepted Answer

The center of mass of the Earth-moon system indeed lies beneath Earth's surface on a line that joins the centers of Earth and the moon, and it also describes the true orbit of the Earth-moon system around the sun. This point, known as the barycenter, is the point around which both Earth and the moon orbit as they together orbit the sun.

The Center of Mass of the Earth-Moon System