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  • Our planet is surrounded by a wispy-thin layer of gas that keeps us warm and allows weather

  • to happen and basically makes all of life on Earth possible. Except... that precious

  • atmosphere of ours is actually leaking, every second, into outer space.

  • Luckily, it's a really slow leak, since for any object--be it a molecule of gas, a rocket,

  • or a cat -- to break the tether of Earth's gravity and escape, it has to hightail it

  • out of here at 34 times the speed of sound.

  • It takes the energy of a metric tonne of TNT to boost a person to that speed, and less

  • energy for lighter objects: 1/10th of that for a cat, for example. Barring a large asteroid

  • impact that can eject large swaths of atmosphere into space, the only gases that regularly

  • escape Earth's atmosphere today are Hydrogen and Helium - the lightest elements in the

  • universe.

  • There are a few ways hydrogen and helium molecules can wind up on a one-way mission to space.

  • Some, near the top of the atmosphere simply get enough energy from the sun's heat to escape.

  • Others are high-energy charged particles that would usually be stopped from escaping by

  • the Earth's magnetic field. Occasionally, though, these speedy electron-lacking particles

  • crash into a neutral molecule with enough force to knock loose--and steal--one of its

  • electrons. Now neutral itself, the speeding particle is free of the earth's magnetic field,

  • and if the collision happens to set it on a course for the stars, that's where it goes.

  • Finally, some of Earth's magnetic field lines are weakened and pushed away from the earth

  • by the solar wind, a violent stream of plasma emanating from our sun. Charged particles

  • guided by these magnetic fields can simply fly off the weak ends like sparks off a live

  • wire.

  • But if our planet didn't have a magnetic field at all, things could be a lot worse. Mars,

  • for example, has no protective magnetic field, and so what little atmosphere it has is constantly

  • buffeted and ripped away by the solar wind. Even with its protective bubble, Earth is

  • losing enough hydrogen to fill a meter-wide balloon every second. No need to worry - it'll

  • take a few billion years before we lose all of our hydrogen this way, but maybe sometime

  • in the distant future, someone will look at Earth and ask, just as we do of Mars now:

  • Was there ever life on this chunk of rock?

Our planet is surrounded by a wispy-thin layer of gas that keeps us warm and allows weather

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B2 magnetic magnetic field earth atmosphere earth magnetic hydrogen

Our Atmosphere is Escaping!

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    VoiceTube posted on 2013/05/18
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