If Mercury is at 0.4 au, the Moon is at 1.0 au, and the inverse-square law holds, how much more light falls on a unit area of Mercury's surface than on an equivalent area of the Moon?

Question

Quizplus · Accepted Answer

The inverse-square law states that the intensity of light (or other forms of energy) is inversely proportional to the square of the distance from the source. Therefore, if Mercury is at 0.4 au and the Moon is at 1.0 au, the light intensity on Mercury would be (1/0.4)^2 = 2.5^2 = 6.25 times greater than that on the Moon.

If Mercury Is at 0