Suppose we are viewing the rings of Saturn from Earth and they are seen edge-on.How long must we wait until the rings are again edge-on? Take the period of Saturn's motion to be 30 years.
A) 6 months
B) one year
C) 15 years
D) 30 years

Question

Quizplus · Accepted Answer

When the rings of Saturn are seen edge-on from Earth, we call it the "ring plane crossing." Since Saturn takes 30 years to orbit the Sun, we can think of the rings as slowly tilting back and forth over this period. This means that the time between ring plane crossings is half of Saturn's orbital period, or 15 years. Therefore, the answer is C) 15 years.

Suppose We Are Viewing the Rings of Saturn from Earth