Earths atmosphere?

Question

When you leave the Earths atmosphere and enter space, is there a definitive line between the atmosphere and space, or do you pass through them gradually. Sorry if this seems a bit vague but i'm not sure how to word it.

Answer 1

its gradual. when you get further from the earths center, the air in the atmosphere has less gravity from the earth pulling on it. thats why the air is "thinner" as you go up a mountain. the vaccum of space is just where the gravity is weak enough that the air isnt pulled toward earth fast enough to extend the atmosphere.

Answer 2

There is no distinct line between atmosphere and the vacuum of space. The atmosphere is densest closest to the ground, and gets rapidly thinner as you gain altitude.
At an altitude of only 3.5 miles, over half of the atmosphere is already below you. At 7 miles, 75% of the atmosphere is below you. At 10.5 miles, 87.5% is below you. At 14 miles, 94% is below you. The atmosphere continues to get thinner and thinner, but it is still measurable even at the heights that some satellites orbit.
As an example, The International Space Station which orbits about 219 miles above the ground, is generally considered to be above the atmosphere. However, even at this height, there still is a tiny amount of measurable atmosphere which causes enough drag to force the ISS to slowly lose altitude over time. Because of this, NASA must periodically boost the ISS to keep it in orbit. The 'height' of the atmosphere also changes over time due to external events. Solar flares cause the atmosphere to 'puff up' and the amount of air at orbital heights increases, increasing drag on satellites in low orbits.

Answer 3

There is a gradual decrease in pressure and density, and as one gets higher, the molecules get excited by the solar radiation (it is above the ozone layer) and would be ionized -- hence ionosphere. It is not like the surface of water where you are either in or out.
There is still a trace of atmosphere at the altitude the space station is, for instance, hence it requires occasional but regular "pushes" to remain in orbit.

Answer 4

Its worded just fine.

No is the simple answer - there are a variety of words like ionosphere and troposhere you can look up if you want to check out atmosphere on something like howstuffworks.com or wikipedia but the answer is no because gravity falls off gradually so as you get higher up you might get fewer and fewer air molecules but there is no barrier where you wont get any, it will just get more and more diffuse.

Answer 5

It is gradual, I have the impression that it is something like 250 miles thick/deep, whatever.

Answer 6

Very gradually.