Why doesn’t the atmosphere (air we breathe) just float off into space?
Some objects in space have atmospheres like Earth and Jupiter. Others like asteroids and the moon don’t have an atmosphere.
Why doesn’t earth atmosphere just drift away into space?
What am I missing about the concept of atmosphere?
In: Planetary Science
Gravity and a magnetic field. Gravity just literally holds the air down like it holds you or your car to the ground, and it’s why helium floats upwards because all the other air is being pulled down below it by gravity
Also, our magnetic field diverts the solar wind away from the surface of the Earth. Other planets and moons that have lesser or no atmospheres sometimes have or had their atmospheres blown away by the solar wind
Rocks sink down in water and don’t float, because they’re heavier than water.
The ocean stays under the air and doesn’t rise up into it, because it’s heavier than air.
The air stays close to the earth and doesn’t float out into space, because it’s heavier than space.
Thank you for all your responses. I appreciate the education.
About [90,000 kilograms](https://phys.org/news/2016-07-curious-case-earth-leaking-atmosphere.html) escapes every *day*. That sounds like an awful lot, doesn’t it?
It is, but it is a miniscule portion of the Earth’s total atmosphere, which is estimated to weigh [about 5.1 quadrillion kilograms](https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html).
9 * 10^4 kg / 5.1 * 10^(18) kg
So we should be good for a little longer, I guess.
The Earth’s gravity pulls down on the atmosphere and keeps it from floating away. Also the Earth’s magnetic field deflects energetic particles coming from the sun. This stops those particles from stripping the Earth’s atmosphere.
Objects in our Solar system that lack an atmosphere are usually less massive than the Earth, so they don’t have as much gravity, and they lack a strong magnetic field, so they aren’t protected from high energy particles coming from the sun.
gravity.
The moon and many planets do have atmospheres. Earth’s atmosphere has many layers, whereas the moons is just one thin layer called the exosphere (outermost layer) same goes for Mercury which you’d practically say has no atmosphere.
Earth’s atmosphere also has an exosphere.
Since gases have different densities, different size planets with varying degrees of gravity will hold onto certain gases that another can’t.
if you’re very close to a star (like an asteroid might pass) then the heat could burn off those gases, or solar winds could blow them away etc. and you’re left with “no atmosphere” or maybe just a very thin one.
don’t forget magnets, magnets prevent solar radiation from blasting our atmosphere like what happened to mars.
There is nothing special about air, its affected by gravity same as everything else. All the air is accelerated towards the ground at 9.81m/s^2 same as any other object on Earth. It cant just drift off any more than rocks or lakes could.
To escape earth, an object must achieve escape velocity, which is pretty fast, 11 km/s. Some molecules of air are of course accelerated to such speeds by solar storms etc, but it’s just not enough to take away all of Earth’s atmosphere.
A couple of key points:
1. Gravity keeps it from just floating away
2. The Earths magnetic field keeps the solar winds from just ripping away the atmosphere
[This](https://www.google.com/search?q=air+pressure+experiment+spatula+sheet+of+paper&client=safari&sca_esv=48020411f2417def&hl=en-us&sxsrf=ADLYWIIf1ev3QdaFGztYtosaorOxQ4y0YA%3A1726253755269&ei=u4rkZu_-D9yv5NoP4-uIyAw&oq=air+pressure+experiment+spatula+sheet+of+paper&gs_lp=EhNtb2JpbGUtZ3dzLXdpei1zZXJwIi5haXIgcHJlc3N1cmUgZXhwZXJpbWVudCBzcGF0dWxhIHNoZWV0IG9mIHBhcGVyMgUQIRigATIFECEYoAEyBRAhGKABMgUQIRigATIFECEYoAEyBRAhGKsCMgUQIRirAjIFECEYqwJI0TdQ7AlY4jNwAngAkAEBmAHKAaABiBWqAQY0LjE5LjG4AQPIAQD4AQGYAhmgAsgVwgIKEAAYsAMY1gQYR8ICDRAAGIAEGLADGEMYigXCAgoQABiABBhDGIoFwgIKEAAYgAQYFBiHAsICBhAAGBYYHsICBRAhGJ8FmAMAiAYBkAYQkgcGMy4yMS4xoAftjwE&sclient=mobile-gws-wiz-serp#fpstate=ive&vld=cid:e5eafc0f,vid:UvMmfacVA24,st:0) is, to me, one of the coolest experiments to show how much air actually weighs.
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