What is the ratio of the light energy that falls on a unit area of Mercury's surface compared to that falling on a unit area of Earth's Moon if Mercury is at 0.4 au and the Moon is at 1.0 au from the Sun?
A) 1
B) 6.25
C) 2.5
D) 16

Question

Quizplus · Accepted Answer

The amount of light energy falling on a unit area from a point source (like the Sun) follows the inverse square law, which states that the intensity of light is inversely proportional to the square of the distance from the source. Therefore, if Mercury is at 0.4 astronomical units (au) from the Sun and the Moon is at 1.0 au, the ratio of their light intensities is (1/0.4)^2 = (1/0.16) = 6.25.

What Is the Ratio of the Light Energy That Falls