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Hypothetical Question about Earth's Distant Future

  1. Oct 19, 2010 #1

    I am not a physicist and I am writing a fictious story about earth's distant future so I would like to base it as possibly close to a plausible scenario. Therefore I ask for your help.

    Assume that the moon is blown up. Would that cause the earth's rotation to slowly fade away? And if yes how long would that take?

    When will the sun be a white dwarf and what would the earth's state be by then? Would earth have been swallowed during the giant phase or not? Would it's rotation change by the sun's transformation?

    If the sun turns to a white dwarf will the habitable zone shrink in diameter and will earth be left outside it?

    If one side is constantly facing the white dwarf how will that affect the climate? Will one side be inflamed or more like a dessert? Would the oceans evaporate?

    In the twilight zone ring between the two sides could vegetation exist without a day/night cycle?

    Thank you in advance and I apologise if hypothetical and uninformed questions are off topic.
    Last edited: Oct 19, 2010
  2. jcsd
  3. Oct 19, 2010 #2
    Well, It is the mark of an educated mind to be able to entertain a thought without accepting it according to Aristotle.

    How would one "blow up" the moon? There will be plenty of gravitational interactions possible, if you scatter it to pieces in all directions, a lot will land on earth, most debris could form a saturnus like ring, but maybe mutual gravity might have it cluster together eventually maybe forming a new moon again. I don't know. Modellers will likely love that kind of exercise.

    However a moonless earth may have a distinct resonance problem between the precession cycle and the obliquity cycle. The gravity of the moon is causing the precession cycle to be much faster (26 Ka) than the obliquity cycle (41 ka). Without that moon the precession would slow down and could get to resonate with the obliquity cycle, leading to a chaotic spin with extreme inclinations of the spin axis, as explained here.

    It is hypothized that this has happened to Venus, ultimately making it lose its spin

    that's it for now :smile:
  4. Oct 19, 2010 #3
    Thank you for the links and the insight.

    Is there a way to estimate roughly how long would a moonless earth's chaotic to finally no spin scenario would take? Or at least make up a timeframe that is believable?
  5. Oct 19, 2010 #4


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    Staff: Mentor

    Last edited by a moderator: May 5, 2017
  6. Oct 19, 2010 #5
    Thank you Evo, very helpful reads both of them!

    The sun has about 4.5 billion years before it starts the giant phase. I wonder how long the moon has til it breaks free from the earth.
  7. Oct 19, 2010 #6


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    Staff: Mentor

    The moon won't break free. Here are two slightly different views on the subject.


    And then NASA.

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