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Is water 'discovered' on another planet hogwash?

  1. Nov 5, 2003 #1
    There had been announcements over the past few years about the 'discovery' of water on planets or moons which were allegedly frozen (including reports of frozen lakes) on which the planet had no atmosphere. Have I been missing some force, they mythical force, which keeps said bodies of water from evaporaring?
     
  2. jcsd
  3. Nov 5, 2003 #2

    chroot

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    Evaporating? You mean, leaving the planet altogether?

    There are few bodies in the solar system which truly have 'no' atmosphere at all.

    - Warren
     
  4. Nov 5, 2003 #3
    The intense cold usually helps too. Water under the surface of a planet, such as Mars, will be deep frozen - like the permafrost in Siberia - and so evaporation will not be an issue.

    Jupiters moon Europa is believed to completely covered in water with a thick ice surface layer. Large cold moons such as Titan can have quite thick atmospheres as although there is not much gravity to stop the particles from escaping, the extreme cold keeps the molecules RMS speed at a sufficiently low level as to keep the atmoshere intact.

    Space is a strange place....
     
  5. Nov 5, 2003 #4

    Njorl

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    Since most of the water on other bodies in our solar system is in solid form, it would be very difficult to wash hogs with it. I suppose, if it were crushed into granules, you could rasp the filth off a hog with it, like you can do with pumice.

    Njorl
     
  6. Nov 5, 2003 #5

    chroot

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    LOLOLOLOL!

    Don't forget that ice sublimates, guys... you'll get an atmospheric vapor pressure just like you would with liquid water.

    - Warren
     
  7. Nov 5, 2003 #6
    Is this Hog made out of Brass? Have you discovered a Brass Hog planet? Idunno. It might be cold enough to freeze the balls off of a Brass Hog. I suppose that Brass Hogs do not mate the same way as an earth Hog. How do Brass Hogs mate?
     
  8. Nov 5, 2003 #7

    chroot

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    Very carefully.

    - Warren
     
  9. Nov 5, 2003 #8
    Serously, now. It is indeed true that ice sublimates. What will prevent the gaseous form of water from filling the vacume of space?
    If you were to put an ice cube in space, wouldn't it (violently) boil off in to space? If you were to create an atmospheric pressure of water vapor, wouldn't it (the water vapor) 'gas off' in the vacume unless it had achieved a large mass? Would the water be depleted in the process?
     
  10. Nov 5, 2003 #9

    chroot

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    Yup. Some of the molecules with enough energy will escape the planet's surface, cooling the planet. Those with too little energy will remain gravitationally bound, just like the oxygen molecules you're breathing right now.

    - Warren
     
  11. Nov 5, 2003 #10
    What is the ratio between planet/body, the mass of water, and the energy on the/at the planet for there to be water in any aggregate mass on/near/in the planet?
     
  12. Nov 5, 2003 #11

    chroot

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    Just use statistical mechanics to solve for the temperature when nearly all (99.9%?) of gas particles have velocities less than the planet's escape velocity (which depends upon its mass and radius).

    - Warren
     
  13. Nov 8, 2003 #12
    What do you define as 'escape'? Escape how far from the planet's ionosphere?
     
  14. Nov 8, 2003 #13

    chroot

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    Escape velocity is the velocity at which kinetic energy equals potential energy. When kinetic > potential energy, the particle can escape to infinite distance.

    - Warren
     
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