Hello Gnees Army,
Earth’s atmosphere is only 1/1,200,000 the mass of Earth itself. So it is a very thin surface surrounding our planet.
So, the question is how does the Earth hold this thin surface of the atmosphere?
The answer is earth’s gravity – the same force that keeps us attached to Earth.
Though you might not realize it or think about it, Earth does continually lose some of its atmospheres to space by the times.
This loss happens in the upper atmosphere of earth, over billion-year time scales.
Molecules in our atmosphere are constantly moving, pushed each other by the sunlight. Some move quickly enough to escape the grip of Earth’s gravity. To move away from the earth, the speed of an object must be a little more than 11 Kmph (kilometers per second).
Suppose, If the Earth were much less massive than Mars – earth’s gravity would be weaker. That’s one reason why Mars lost most of its original atmosphere.
That’s why, in the environment of our heavier Earth, not all particles are equally likely to escape.
For instance, Light materials like Hydrogen and Helium, typically move faster than heavier ones, like Oxygen and Nitrogen. These types of light particles are more likely to reach escape velocity and escape to space.
That’s why light molecules are rare in our atmosphere, in contrast to their abundance in the large universe.
This Earth’s atmosphere protects life on Earth in many ways. It absorbs harmful UV radiation from the sun, helps keep Earth’s surface warm via the greenhouse effect, and reduces temperature extremes between day and night. Keeps Earth livable!
Why doesn’t empty space pull the Earth’s atmosphere?
So, The answer is – Earth’s Gravity!
Thanks for reading.