Why Is It So Much Easier to Determine the Length

Multiple Choice

Why is it so much easier to determine the length of the day on Mars than on Venus?

A) Mars' atmosphere is generally pretty clear (so the surface is visible) while Venus is always cloudy
B) Mars rotates really slowly, so it's easy to follow; Venus rotates so fast, it's hard to track
C) Mars is much larger in diameter than Venus is, so it's easier to see
D) Mars is always much closer to the Earth than Venus
E) Mars is always visible in our nighttime sky, while Venus is only visible in the daytime sky
Section 10.2: The Geology of Venus