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If the moon was vapourised, would it recondense or get blown away by solar wind?

  1. Jul 22, 2012 #1
    If the moon was vapourised, would it first recondense or get blown away by solar wind?
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  3. Jul 22, 2012 #2


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    I suspect that to get a meaningful answer to this, you'll have to be a LOT more specific about the exact characteristics of what you mean by "vaporized"
  4. Jul 22, 2012 #3
    Correct. (Well, the OP said "vapourized" instead of "vaporized." =P ) I'll assume they mean that just the particles are blown apart. It depends on how they're blown apart, but I imagine there's a low probability of it recondensing. Note that this is a complete guess.
  5. Jul 22, 2012 #4
    By vapourised, I mean turned into vapour. As in, a gas.
  6. Jul 22, 2012 #5


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    And by what mechanism do you imagine this might happen? If you are talking about magic, whereby the entire mass of the moon suddenly becomes vapor, what diameter do you imagine it will take?

    If by a large explosion, by what amount of force do you see as creating the event.

    I say again, your question as posed is vague to the point of being useless.
  7. Jul 23, 2012 #6


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    To dismantle the Moon would take at minimum as much energy as its gravitational binding energy. The manner in which this arrives is important as it's not just going to be evenly spread.
  8. Jul 23, 2012 #7


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    If it's just magically "turned into gas" while nothing else happens, then that gas will be highly compressed and the pressure will be enormous. Some of it will condense into a solid, some of it to a liquid, and almost all of it will be accelerated away from the center. The question of whether all of it will fall down again will depend on the speeds that the particles will reach. The required speed for a given particle will depend on its initial distance from the center. I haven't done any calculations to see what speeds will be necessary. I also don't know if particles that are moving fast enough to escape the Moon will be fast enough to escape the Earth.
    Last edited: Jul 23, 2012
  9. Jul 23, 2012 #8


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    For some perspective: TNT (trinitrotoluene) is normally a solid. Its molecule is very unstable (it wobbles like a Jenga tower). If you shake it vigorously, the tower comes tumbling down, and the molecule is able to rearrange itself in a much more stable configuration. The thing is, this more stable configuration, it doesn't bond well anymore with its neighbours. So it's not a solid, but a gas. (I'm getting to my point.)

    As a gas, its molecules (mostly CO, CO2 and H2O) take up a LOT more room than they did as a solid. So the volume of the gas expands. It does so very rapidly and releases a lot of heat in the process. This is experienced as an explosion. And that's TNT.

    So, if the Moon were vaporized, it would not do so as a well-behaved solid turning to dust. As a gas, it would want to expand rapidly. i.e. explode.

    The moral of the story is: It's pretty hard to separate the outcome of vaporization from the mechanism of vaporization.
  10. Jul 23, 2012 #9


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    Well said. That's exactly what I've been trying to get him to see, but he doesn't seem to buy it.
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