The Moon: What is it's purpose?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by John99, Jan 23, 2009.

  1. draqon Banned Banned

    The moon was part of Earth once. If it was never there (no impact to separate it from Earth) than Earth would be much more massive...which would mean that its orbit around the sun might have been different (meaning no life...if it is beyond a habitable zone)
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  3. Nasor Valued Senior Member

    Based on what? Our current sample size of one?
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  5. spidergoat Valued Senior Member

    Based perhaps on how early in the Earth's history it developed. Practically as soon as the world cooled enough...
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  7. John99 Banned Banned

    Some interesting links provided. I was thinking about this whole moon and if it has any measurable effect on Earth wile reading the other moon thread.

    While i am aware of most of what has been stated and my intention is not to start a conspiracy thread or disagree with any of the known theories but the real question is as far as its effect relating to gravitational forces is how do we really know it is true?

    Of course it goes w\out saying that the sun has a definite purpose that we can feel and see but can the moon just be an object that is closest to the Earth so much of it purpose is just assumed? What i am wondering is if a planet cpable of sustaining life would need a sun but really does not need a moon and the proximity of this moon is merely coincidental.

    I read that large objects are also attracted to the moon so they have less of a chance hitting the Earth but there are no known observed large objects that hive hit the moon since we have been able to view it clearly enough. Also, debris does hit the earth on a daily basis but of course it is small and much gets burned up in the atmosphere.

    Bottom line:

    Is it at all possible that it does absolutely nothing and serves no purpose whatsoever?

    We can assume the gravity part but how can we relly know this to be true?
  8. John99 Banned Banned

    An example would be if we fired rockets at the moon and then pulverized the remains down to nothing and at the same time extracted its resources.

    Now you look up and there is no more moon but then nothing changes.

    I am simply stating- what if?
  9. John99 Banned Banned

    or if we fire a rocket at the moon attached to a long cable and try to reel it in closer.

    this post and the one above is simply to provide some insight and perhap add some visualization, so dont get overly excited or take this part literally. the main point is the previous post - #24.
    Last edited: Jan 23, 2009
  10. D H Some other guy Valued Senior Member

    This is an important caveat. Until we see extra-solar planets that have incontrovertible signs of life all of this must be viewed as conjecture. That said,

    You are assuming a lot here, swivel:
    • You are assuming the Earth would still be warm and wet without the moon. Why not awfully hot and bone dry, like Venus? Venus did not benefit from a collision with have a large protoplanet that stripped away most of the primordial atmosphere. Venus is inhospitable to life.
    • You are assuming the Earth would be stable. Think of Venus again. It's high obliquity once again makes it inhospitable to life. The presence of a large moon stabilizes the Earth's rotation axis. Without the Moon, couplings with Jupiter might well have led the Earth down the same path followed by Venus.

    Laskar, J. "Chaos in the Solar System",

    Correia, A.C.M. and Laskar, J., "The four final rotation states of Venus", Nature 411, 767-770

    Lecar, M., Franklin, F.A, Holman, M.J., Murray, N.W., "Chaos in the Solar System", Annual Review of Astronomy and Astrophysics 39, 581-631

    Again, you are assuming the Earth would have cooled, period.


    Whoa. What is all this crap about "purpose"? The Sun and Moon don't have a "purpose". They just exist. If they didn't exist, and if they are necessary for life (the Sun is definitely necessary for life and the Moon is probably necessary for life), we wouldn't exist. That doesn't mean they have a "purpose". It merely means they are a prerequisite for life. Somewhere else in the universe (multiple somewhere elses in the universe) there exists a third generation class G star with an Earth-sized planet orbiting at just the right distance from the star that has a large moon that helped set up and stabilize the conditions for life.
  11. swivel Sci-Fi Author Valued Senior Member

    Based on the precursors to life existing in stellar debris. Based on experiments that show how easily these precursors combine into the building blocks of RNA. Based on very recent experiments that show man-made RNA exhibiting all the features of life.

    DH, I'm not assuming much at all. We have water in liquid form because of our proximity to the Sun. Venus is boiling hot and Mars is frigid. The moon has nothing to do with our liquid oceans other than its effects on the tide.

    I'm not downplaying the power of the moon, just commenting on how easy life forms. Extremophiles and subterranean organisms bear this out. Rebounds post-extinctions also support this claim.
  12. Nasor Valued Senior Member

    I am a chemist, and I am well aware of how easily common elements combine into small biomolecules. But I don't think it's possible to put any sort of reasonable estimate on the odds of life arising. What are the odds of a collection of random amino acids and amphiphiles actually turning into something that is alive? How many cubic meters of small organic molecules, at what concentration, and with howmuch influx of energy would you need before there is a 50% chance of life arising in 1 million years? A million cubic meters? A trillion? 10e30? No one really has any idea.

    As I said, our current sample size is one. A person who wins the lottery might think it's easy to win the lottery, especially if he sees lots of other lottery tickets floating around. But he can't actually know whether or not its easy to win unless he's able to find out how many other people have won the lottery.
  13. Lord Vasago bcd Registered Senior Member

    the moon keeps our planet stable. without the moon our planet would be shaking so hard that it would heat up from the fricksion of the tektonic plates. the weather would be ultra violent. basicly our planet would become unhabbitable for human life.

    and don't forget that the moon is moving away from earth. someday in a far futher the moon will loose his effect on our planet.

    als for life on mars or venus. check out some extrofiles living on our planet at -100c and +500c. In pure acid; in total darkness, even without oxcigen. I've seen several programs on this topic and that of the moon on Natgeo and Discovery.
  14. swivel Sci-Fi Author Valued Senior Member

    Take your laboratory. Make it the size of the planet. Remove all predators and all competition in every single niche. Run experiments in this Earth-sized laboratory 24/7/365 in every gradient of heat, wetness, acidity and toxicity. Do it for 1,000 years. The precursors for life (RNA/DNA) are guaranteed.
  15. Saquist Banned Banned

    Only speculation on the available facts.
    The lack of plates tectonic on other rocky worlds.

    Now that could also be for three reasons,

    1. The magma layer's constant circulation and liquid form
    2. The preasure exerted by the weight of water on the Earth's thin crust.
    3. Lunar gravitational force.

    Looking at the options and thus observing the other planets in the inner circle the option narrow.
    Earth has a sizable moon with considerable gravitational influence.

    Venus is a similar size as the Earth.
    Venus has no volcanic activity
    Venus surface is far thinner than Earth's lithosphere
    Venus' surface has one general age.
    Venus has no plates tectonic
    Venus has no water
    Venus has no moon

    Mars is smaller
    Mars has no volcanic activity
    Mars has no plates tectonic
    Mars has very small moons
    Mars has no free flowing water.
    The lack of a considerable Mag field implies no core dynamo

    Where these planets lack, Earth has in abundance.
    Gravity even of the moon's size has a clear effect on the atmosphere, hydrosphere and lithosphere. The Earth's oceans experience tides, the atmosphere swells during full moons. The magma layer too is quite manipulable to the same gravitational forces.

    It seems a likely the Moon at least continues to assist this process or perhaps even began the process some time previously.
    Speculation, Yes.
  16. Nasor Valued Senior Member

    As I already said, small bio-molecules seem pretty much guaranteed under the right conditions. But no one has any idea what the real numbers are for how likely life is. Perhaps there was a 90% chance that life would emerge in just 10 million years, and it was very bad luck that it took as long as it did on earth. Perhaps there was only a 10% chance that it would emerge in the first billion years, and it was very good luck that it happened so quickly. No one has a clue - drawing any kind of statistical information from a sample size of 1 is impossible.

    Advanced aliens who had been watching earth since its beginning and who knew about how likely life is might be amazed that it happened so quickly here, or they might be amazed that it took so long. Or perhaps they wouldn't be surprised at all, and because we were exactly average.
  17. swivel Sci-Fi Author Valued Senior Member

    Looking around I would put the figure at 100%.
  18. draqon Banned Banned


    Venus is a Volcano all around planet.

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  19. D H Some other guy Valued Senior Member

    I gave three reasons, with references, and there you go assuming away.

    1. Your are assuming that the Earth would have still been hospitable to life (Drake's n[sub]e[/sub]) had Theia not collided with the Earth. This collision may well have removed a significant fraction of the Earth's primordial atmosphere. A thicker atmosphere would have made it more likely that the Earth would have entered a runaway greenhouse effect.

    Melosh, H.J., "Planetary science: The history of air", Nature 424, 22-23
    Ahrens, T. J., Shen, A.H., Ni, S. "Giant Impact Induced Atmospheric Blow-Off", Shock Compression of Condensed Matter -- 2003: Proceedings of the 13th Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter. 1419-1422.

    2. You are assuming that the Earth would have remained hospitable for complex life (Drake's f[sub]i[/sub]; Drake's equation doesn't cover this explicitly. It makes a miracle leap from life to intelligent life.) Life, if it existed at all, would look drastically different if our day was more than a year long (e.g. Venus). I posted references in post #27. You ignored them.
  20. Nasor Valued Senior Member

    Right. And in other news, since I won the lottery the third time I played it, it is clearly safe to assume that there is a 100% chance of winning the lotter if you play it three times. Can't argue with that logic

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  21. Saquist Banned Banned

    Negative: All of the planet is dormant.
    Venus' surface age is far too young. There are formations but none of them are conducive to plates tectonics. Please do not confuse "no volcanic activity" to mean never had volcanic activity.
  22. Trippy ALEA IACTA EST Staff Member

    This isn't quite accurate, and as a chemist you should know this. As a chemist you should know that we can make measurements of various steps of the reactions, and use these to infer things about the over all reaction sequence.
  23. Trippy ALEA IACTA EST Staff Member

    This doesn't neccessary exclude the possibility of a series of smaller impacts that are sufficiently large to strip away the atmosphere, but not so large as to result in the formation of the moon though.

    Having said that I agree with you and Nasor, for the most part.

    With only a sample of 1 it is very difficult (but not impossible) to infer anything sensible about what might have happened had the earth evolved a little differently.

    I also agree that had there been no impact to create the moon (assuming that theory is correct) then the earth would probably be a very different place, although, I don't know if I'd go as far as suggesting Venusian extremes (remembering that Venus recieves significantly more insolation than the earth does).

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