Chapter 18, Problem 42A

To determine

To explain: The reason behind the redness of the Moon during a lunar eclipse.

Explanation of Solution

Introduction:

A lunar eclipse take place when the Moon goes in to the Earth’s shadow. This can merely happen when the Sun, the Earth, and the Moon are aligned in the same line with the Earth in between the Sun and the Moon.

When the lunar eclipse takes place, Earth blocks the sunlight reaching to the Moon. But, the sunlight which is refracted from the Earth’s atmosphere is focused inward and falls on the moon. Since the dispersion is more for the blue light, only red color light gets reflected off from the Moon in the direction toward the Earth. Hence Moon looks red during a lunar eclipse.