Breakdown: Why does Earth’s atmosphere not drift off into space?

MEMPHIS, Tenn. (WMC) - After all, it is only air. What keeps it here?

An explation from NOAA (The National Oceanic and Atmospheric Administration) :

The answer in a word is... Gravity!

Fortunately for us, Earth’s gravity is strong enough to hold onto its atmosphere. Mars, for example, is less than half Earth’s size and around one-tenth Earth’s mass. Less mass means less gravitational pull. Mars’ atmosphere is only about 1/100th as dense as Earth’s. And, by the way, it is mostly carbon dioxide (CO2).

Click here for more Mars facts!

The air at the bottom of the atmosphere is under a lot more weight than the air nearer the top.

Like the acrobat at the bottom of a stack of acrobats, the air at the bottom of the atmosphere is under a lot more weight than the air nearer the top. That means, the air nearer Earth’s surface is squished by the air above it, and is thus denser.

The higher you go in the atmosphere, the thinner the air becomes. Ninety-nine percent of the air is in the lowest 19 miles of the atmosphere.

So to sum up, Earth’s gravity is strong enough to hold onto its atmosphere and keep it from drifting into space.

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