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B What would happen if the Moon wasn't there?

  1. Jan 11, 2017 #1
    So 2 scenarios..

    1. There never was a moon, could we expect life in any form?

    2. If it was removed now what might the effect on earth be?

  2. jcsd
  3. Jan 11, 2017 #2
    1. Probably not. This answer also ties in with your second question. Without the moon (assuming it just vanished or never existed) our planet would be very different. First off, the moon has a tidal force on our planet, which causes the sea levels to rise and fall periodically. Those tides are actually responsible for the movement of very crucial nutrients, which without would not result in the diverse lifeforms which first began in our oceans. Consequently to answer your question, (2), without the moon we would not have tides, (very little, as the sun does have some affect, but not much). Also our planet would rotate faster, as a consequence of tidal force, is tidal "friction", which acts like a drag on our rotation. However if the moon was destroyed, blown up for example, most likely all life on our planet would be destroyed. Overall... without the moon earth is not same.

  4. Jan 11, 2017 #3
    The primary effect of the Moon on Earth is that it causes tides.(The Sun does too though to lesser amount)
    Tides in the early seas may have played a significant role in life developing, but there isn't a strong argument that tides are essential for life.
    If the Moon now disappeared this could disrupt ecosystems of coastal margins, which have adapted to the tide cycles.
    It probably wouldn't upset land based and deep sea life very much.
  5. Jan 11, 2017 #4


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    Solar tides are half as large as lunar. That's hardly insignificant. The difference would have been larger in the past, but what is the argument that makes any specific tidal height necessary for life?
  6. Jan 11, 2017 #5

    This is mostly what I'm basing my argument off (as well as basic knowledge). I was actually unaware of the solar tidal affect on the earth (I think my misconception was thinking it was 1/36 or 1/64 as powerful). Though the main premise of the argument is in the fact that tidal forces are responsible for the movement of nutrients. Specifically (stated in the journal I linked as well as other sources), Phytoplankton are key in biological development. And their movement is very much the result of tidal action. They are actually responsible for within 50% to 80% of the oxygen creation on our planet. More specifically to your argument, I'm pretty sure that weaker tidal action would result in the stagnation (relative to the force) of nutrients in the oceans.
  7. Jan 11, 2017 #6
    All life? I find that difficult to believe that the Moon vanishing would lead to the death of all bacteria and organisms living on the bottom of the oceans.
  8. Jan 11, 2017 #7
    Probably should have specified what I meant. If the moon suddenly exploded the planet would suffer from the debris of the explosion. The entire structure of the earth would change (literally from kinetic impact) Not only this but the actual core structure of the earth is affected by the force of gravitational attraction. So the instability could cause huge eruptions. Probably shouldn't have generalized it, but let's be honest... it would be pretty bad

  9. Jan 11, 2017 #8
    I figured that's what you probably meant. I wonder what it would really take to wipe out all life including every last bacterium.
  10. Jan 11, 2017 #9


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    Temperature like Venus might do it.
  11. Jan 11, 2017 #10
    Venus is an extreme example, but some bacteria might survive there underground. Mercury too www.lifeonmercury.com
  12. Jan 13, 2017 #11
    This is originally from the History Channel's "Universe" series, not from National Geographic as the name of the video states.

  13. Jan 14, 2017 #12


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    Removing the moon would be an issue, but, I doubt it would seriously impact life on earth that originated in deep sea vents - albeit might significantly delay its evolution into multicellular organisms. I question whether our current level of knowledge can decide this issue.
  14. Jan 15, 2017 #13
    I once read a material saying that moon has reduced the rotation speed of the earth in the past 4 billion years. So indeed moon has shaped the rhythm of life on the earth. If we remove the moon now, I reckon the tides will be gone (as people said) and also the rotation speed of the earth will change.
  15. Jan 15, 2017 #14
    Don't worry ... it is slowly "removing itself", moving away from earth by 4cm/year (1m in 25 years). It's out now (away from earth) at ave 375,000km, in the past (e.g. dinosaur time[?]~ ...) was even at 60,000km, further back min 20,000km I think, and in 2.5 billion years it will go further out by another 100,000km (at the said rate).
    So it's all happening. We'll see it all! Just stick around! ...
    But yeah, we got time!
  16. Jan 15, 2017 #15
    But if it weren't for the moon, ...we wouldn't exist! ...
    Also we're just lucky now to have total solar eclipses (equal phenomenal diameter to the sun). Hasn't been always the case! But no coincidence, nothing magic either! ... just passing through (just like us all ...!) ...
  17. Jan 15, 2017 #16
    Something else might though.
  18. Jan 15, 2017 #17
    Could ... some kind of life. Earth seems to like it ...
  19. Jan 16, 2017 #18


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    Our planet would not rotate faster. It would stop getting slower over time, i. e. a day would stay 24 hours long and we wouldn't need more and more many leap seconds.

    As Bandersnatch mentioned already, we would still have tides. It is not even clear if the tides were necessary for the evolution of life, so half the tides could have been fine as well.

    If the moon would vanish now, the long-term stability of the rotation axis of Earth would suffer - the seasons could get more or less extreme over time.
  20. Jan 16, 2017 #19

    Fervent Freyja

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    Really, all this isn't known for sure, yet. It's unclear whether life began in tidal waters, that would make a difference. We also recently found that the moon is older than previously believed.

    I would be curious to know the importance of the moon concerning the thermodynamics of the early earth- why should the moon not be a major reference to its evolution?
  21. Jan 18, 2017 #20
    Solar tide is less than half of lunar tide, but still considerable. However, without a moon the seas would be a lot quiter. This would probably lessen the mixing of cold and warm water and therefor of nutritients.
    If the moon would explode, its center of gravity would be unaltered. Debris would have effect, but the movement of earth would not be affected. The question was, where would we be if the moon hadn't been there? I gather that a large part of the initial momentum at the time earth took form was absorbed by the moon. Without the moon, earth would rotate considerably faster, so days would be shorter and differences between polar areas and equatorial areas would be larger, especially in climate and weather conditions.
  22. Jan 24, 2017 #21


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    But, would the Earth still have a magnetic field if there was no Moon. The Moon adds to the tidal flexing of the crust and mantle, heating it.
    The last I heard, no-one knows exactly how the magnetic field is formed, but it's something to do with flows of molten iron (and huge iron crystals I think)
    Without a magnetic field, the Earth's atmosphere would have been denuded by the Solar Wind over billions of years. Particularly the hydrogen in the atmosphere, from H2O. Lose the H2O, and it's going the way of Venus.
  23. Jan 24, 2017 #22
    Actually water vapour is itself a greenhouse gas, but unlike CO2 we are not concerned that the amount of it increasing rapidly.
    As for the Earths magnetic field, while it is not fully understood the basic mechanisms are roughly as you say, to do with flow of molten iron in the core.
    There is no reason to suppose that the Moon has anything to do with it.
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