Chapter 9, Problem 1E

What is the composition of the Moon, and how does it compare to the composition of Earth? Of Mercury?

To determine

The composition of the Moon and to compare it with the composition of Earth and Mercury.

Explanation of Solution

Introduction:

Moon is the only natural satellite revolving around Earth and is considered to be geologically dead. Mercury is similar to the Moon in several ways as both lack atmospheres and lacks geological activity.

The average density of the Moon is about $3.3\text{g}/{\text{cm}}^{\text{3}}$. This shows that it is mainly composed of silicate rocks and lacks iron and other metals which are present on Earth. Also, the Moon does not have a large metal core like Earth. Water and other volatile materials are also absent from the lunar crust whereas, earth has liquid water present on its surface.

Mercury’s density is higher than that of the Moon as Mercury is largely composed of metals. Mercury consists of a metallic iron-nickel core which amounts to $60\%$ of its total mass. Also, Mercury has a weak magnetic field, unlike the Moon which suggests the presence of some liquid core present in it.

Conclusion:

Therefore, the comparison between the composition of the Moon with Earth and Mercury is as mentioned above.