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Thread: Moon Worship

  1. #1 Moon Worship 
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    I was thining about life else where through out the universe and i just cant get over our moon.

    How vital is it to the development of inteleigent life like us?

    ive heard that with out the moon our poles would not stay at a constant tilt and throw off the climate and the seasons.

    Even if a planet is the right size, in the safe zone, and has a preferable atmostsphere would it be inhabitable if it didnt have a moon somewhat like ours to hold it steady?


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  3. #2  
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    Any answer of course would be little more than a guess based on what happened to our rock.

    The obliquity of Earth isn't constant, but shifts in a small margin of a few degrees.

    Who can guess the effects on evolution.

    Would more profound seasons from larger shifts of obliquity hamper or enhance the rate of evolution?

    Or were other effect far more pronounced such as:
    Did higher tides, and shorter days, associated with the closer moon of the past enhance and speed up evolution or act to delay evolution --particularly as life evolved from marine to land environment?

    I know, you asked first :-)


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    Forum Masters Degree Numsgil's Avatar
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    Has the moon's tidal effects on the crust and mantle helped keep the Earth's interior liquid? Venus and Mars could potentially have life, but they (probably) don't. They also don't have active geological processes like volcanoes and earthquakes. If there's a fundamental role for the Moon in life formation and development ,I'd say it's been keeping the mantle liquid. Assuming the math works out properly for that
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    so the moon doesnt keep the earth on its constant till?

    so there could be life on a planet with no moon
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    the moon has active volcanoes, don't you know that? Scientist only focus the exploration of the other planet because it is surrounded by sun and exposed to sunlight but the Moon is darkened. Event the moon is near of Earth unlike Mars so why they focus on other planets than Moon. We can also live in Moon but less of gravity than Earth, no Sunlight Exposure. No sunlight no energy. ehehe
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    Forum Masters Degree Numsgil's Avatar
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    Wow. So wrong.

    The moon is not geologically active. There are no moon volcanoes. And aside from lunar eclipses half of the moon is always in direct sunlight, just like all other astronomical bodies.
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  8. #7  
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by Numsgil
    Venus and Mars could potentially have life, but they (probably) don't. They also don't have active geological processes like volcanoes and earthquakes.
    The surface of Venus is largely a volcanic surface. While there is no clear evidence of current volcanic activity, the consensus view appears to be that such activity is ongoing. There is clear evidence on Mars of volcanic activity within the last couple of million years. That is pretty much 'now' in geological terms.
    Quote Originally Posted by Numsgil
    If there's a fundamental role for the Moon in life formation and development ,I'd say it's been keeping the mantle liquid.
    The mantle is not liquid. (I am at a loss as to why this view is so widespread amongst otherwise well informed people.) I cannot readily do the math, but I understand the contribution of tidally generated heat in the interior of the Earth is at least an order of magnitude less than that contributed by radioactive decay.
    Quote Originally Posted by Jon not Ron
    so the moon doesnt keep the earth on its constant tilt?
    Yes it does. The small variation, over a few degrees of axial tilt, would be over tens of degrees were it not for the stabilising effects of the moon.
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    Moderator Moderator Dishmaster's Avatar
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    Quote Originally Posted by John Galt
    Quote Originally Posted by Jon not Ron
    so the moon doesnt keep the earth on its constant tilt?
    Yes it does. The small variation, over a few degrees of axial tilt, would be over tens of degrees were it not for the stabilising effects of the moon.
    I have seen this claim very often, but never actually found a real proof for it. I always thought, a force free environment produces more stable conditions than one without. Do you have a reference to back that up?
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  10. #9  
    Forum Masters Degree Numsgil's Avatar
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    Quote Originally Posted by John Galt
    Quote Originally Posted by Numsgil
    Venus and Mars could potentially have life, but they (probably) don't. They also don't have active geological processes like volcanoes and earthquakes.
    The surface of Venus is largely a volcanic surface. While there is no clear evidence of current volcanic activity, the consensus view appears to be that such activity is ongoing. There is clear evidence on Mars of volcanic activity within the last couple of million years. That is pretty much 'now' in geological terms.
    My knowledge must be dated then. I was under the impression that all other celestial bodies in the solar system, with a few exceptions (Io, for instance) are geologically dead. Do you have an article or something I can use to refresh what I know?

    but I understand the contribution of tidally generated heat in the interior of the Earth is at least an order of magnitude less than that contributed by radioactive decay.
    So it's unlikely that the Moon is the reason Earth is still geologically active? Actually, why is Earth so geologically active? Is it because we're the largest terrestrial planet? Did we just luck out?
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  11. #10  
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by Numsgil
    My knowledge must be dated then. I was under the impression that all other celestial bodies in the solar system, with a few exceptions (Io, for instance) are geologically dead. Do you have an article or something I can use to refresh what I know?
    In geological terms, for a planet thought to have been 'dead' for a billion years or so, there is interesting material from Global Surveyor of flows within the last 100 million years.
    http://physics.ship.edu/~mrc/astro/N.../ob990203.html

    100 million years may seem quite old, but then there is the work of Vaucher et al, that indicate flows as recently as 10 million years. (That's only twice as old as Lucy, I think!)
    http://www.cosis.net/abstracts/RSTGV...GV-A-00583.pdf

    And we can continue with these more recent observations "Here we show that calderas on five major volcanoes on Mars have undergone repeated activation and resurfacing during the last 20 per cent of martian history, with phases of activity as young as two million years, suggesting that the volcanoes are potentially still active today."
    That comes from Neukum et al, "Recent and episodic volcanic and glacial activity on Mars revealed by the High Resolution Stereo Camera" Nature 432, 2004.

    So, all in all, there's quite a lot of evidence for recent volcanic activity. I understand studies of the probable amount of thorium and potassium in the mantle (based upon the observed amount at surface) show sufficient heat could be present to account for a small amount of volcanic activity.

    Quote Originally Posted by Numsgil
    So it's unlikely that the Moon is the reason Earth is still geologically active? Actually, why is Earth so geologically active? Is it because we're the largest terrestrial planet? Did we just luck out?
    I am not sure if there is a full consensus on this, but my personal take on it is water. On a dry planet it is more difficult for plate tectonics to operate. Such seems to be the case on Venus. On Earth, heat transfer from the interior occurs mostly from plate tectonics. (Specifically the eruption of mid-ocean ridge basalts.) On Venus, in the absence of plate tectonics heat builds up in the interior leading to a major resurfacing event around 600 my ago.

    Quote Originally Posted by Dishmaster
    Do you have a reference to back that up?
    Ward and Brownlee discuss this in their popular work Rare earth : why complex life is uncommon in the universe. I wouldn't normally offer a popular science work as a reference for something like this, but Ward has done work in the area of Earth's rotational stability and I find his summary acceptable. He and Brownlee note that in the absence of the moon the effect of the Sun and Jupiter would produce long-term, severe, changes in obliquity. The moon overides these effects, maintaining the current few degree variation that we currently experience.
    If I can find something more precise, with the math, I shall post it.
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