Why is the atmosphere much rarer on the moon than on the earth?

The atmosphere on the moon is much rarer and the temperatures on the moon are extreme ranging from boiling hot to freezing cold depending on the area of moon’s surface exposed to sunlight. The atmospheric gases on the moon are very much rarer on the moon.

As moon rotates on its axis in about 27 days, lunar day-time is about 13.5 earth days and lunar night-time is about 13.5 earth nights. The lunar atmosphere varies depending upon these lunar day and night times also.

The gases on the earth remain in the earth’s atmosphere because of the gravitational pull acting on. These form a thick blanket around the Earth’s surface. Moon has very low gravity compared to earth, because of which the atmosphere on the moon is very thin.

This rarer atmosphere is called as an Exosphere, which doesn’t hold many gases, while the ones present there are widely spread out and hence they rarely collide with each other. If we compare, there are only 100 molecules per cubic meter on the moon’s atmosphere, while there are 100 billion molecules on the Earth’s atmosphere.

Because of the thin atmosphere on the moon, the dust layers or footprints are not easily erased. Because of this scarce atmosphere, the moon doesn’t maintain its temperatures for long. They vary so widely that the sunny side of the moon would be 273°F (134°C) while the temperatures of the dark side would plummet to 243°F (-153°C).