Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Is moon useful to the earth ?

  1. Jul 12, 2003 #1
    Does moon have anything good to us, other than for ancient people to imagine a lot of myths about it!:wink:
  2. jcsd
  3. Jul 12, 2003 #2
    One of the effects of having a moon near this planet is that it causes an oceanic tidal effect on a regular cycle.

    This regular tide exposed sea creatures to air and they adapted over a lot of time to become land creatures. That's one of the evolutionary rungs in the ladder to where we are today as humans.

    Without the moon things may have taken quite a different turn for humanity... if, in fact, humanity could have existed without it.

    As for the moon being "useful" to the earth... I don't think the earth has any utilitarian needs whatsoever.
  4. Jul 12, 2003 #3
    Mmmm..... It gives us a good supply of moon rocks.:wink:

    And....let's see...it makes a nice target for developing nations to try and hit with missiles & rockets.

    And of course, it gives us hours of fun & pleasure speculating how it was created, if there is life on the moon, did aliens land there....

  5. Jul 13, 2003 #4
    The moon could have many uses for humanity in the future as well; for example
    • as a potential source of natural resources
    • another base from which to launch future interplanetary/interstellar missions
    • a base for astronomers to study the cosmos without atmospheric interference
    Dependent, that is, on when man returns to the moon - are there any plans to do so? :smile:
  6. Jul 13, 2003 #5


    User Avatar
    Staff Emeritus
    Gold Member
    Dearly Missed

    The late John W. Campbell, onetime editor of Analog magazine, once had an editorial on the origin of life on earth. At that time scientists were having trouble with it because biotic molecules could easily form in the oceans but could just as easily dissolve again. So they postulated tide pools where the biotic-saturated water could be trapped and dry and allow the molecules to "set'.

    Campbell, like quantumcarl, pointed out: no moon, no tide, no tide pools.
  7. Jul 14, 2003 #6
    (Like I always say)

    Analog rules!
  8. Jul 14, 2003 #7


    User Avatar
    Science Advisor

    There are some flowers that depend on the moon for there growing process. I don't know any by name, just remember my aunt telling me about a few plants she has that blooms in the middle of the night.

    As far as usefullness, it is nice to have the lil bit of light we get from it.

    And, lets not forget how much fun it can be picking on the people who make up myths about the moon. (who says they have to be ancient?)

    So yes, I'd conclude its quite usefull.
  9. Jul 15, 2003 #8
    Tidal effects came straight to mind. If ever we find another sentient race there is a good chance their home world will have a big satellite like ours. Like the first respondant has already stated, we might not have even reached the evolutionary equivalent of lungfish without the moon.

    We would never have developed a calendar without the lunar cycle to work from.

    Helium 3 could be a useful source of energy when fossil fuel reserves begin drying up. Its extremely rare here on Earth but rather common elsewhere. The closest abundant source of H3 is the moon.

    The moon might influence our geomagnetic field in some way. I'm just guessing. Since it drags on the outer oceans of water I'm assuming it has some effect on the inner oceans of magma too.

    One day it will be the launchpad from which terran life will reach beyond its cradle and out towards the stars. With any luck and dramatic license willing.

    Anything good for us? Well, for us humans it was the first clear indicator that other Worlds exist. Despite being blind to it from familiarity I'm guessing it probably did register on the minds of early thinkers. It gave our first astronomers something poignant to look at. It united much of the world in awe and wonder when the first astronauts climbed down a ladder on to its dusty surface.

    Ok, I'm done.
  10. Jul 15, 2003 #9


    User Avatar
    Science Advisor

    We might not have gotten as far as lung fish- look at Venus. It's atmosphere reflects so much heat back to the surface that it has an enormous temperature (greenhouse effect). One of the effects the moon may have had is to pull some atmosphere off the earth reducing that effect.
  11. Jul 16, 2003 #10
    Also, primordial soup might have needed the occasional stirring to 'brew'. It had the ingredients, it was heated with a bathing of cosmic rays and other background radiation many times higher than today's levels. It certainly had time to develop. Yet I wonder if a still ocean could have produced the complex molecules we call life. Without waves and currents I doubt early life would have developed very far. You have to stir up the pot to really mix up the elements in a soup and make something interesting. Ok, I've run out of allegories.

    Is there a way to change my sig to a hyperlink?
  12. Jul 16, 2003 #11


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    As far as tides go, the sun produces them also, just not as large.

    If you needed larger tides for life to develop, you just need to orbit closer to the Sun. Of course, in order for your planet to remain in the temperate zone, it would then have to orbit a cooler star.

    This could be advantageous to the propensity of life in the galaxy in a number of ways:

    1: It wouldn't require a terrestrial type world to have an over-sized moon. (very likely a very extremely rare occurrence)

    2: Cooler stars tend to be more numerous.

    3: Cooler stars have longer lifetimes, giving more time for life to form and evolve.

    Thus, it may be more common to find life around class K stars than class G ones ( We just might be the rare exception)

    Of course, all this assumes that large tides are needed in the first place.
  13. Jul 16, 2003 #12
    It was found that Mars has a tide going on right now. It is caused by the Sun, as you suggest. The tidal material is the magma at the centre of Mars. There is a slight buldge created as the tide moves around the surface of Mars. The Earth has a similar tidal magma, effected by the Sun. This may be a contributing factor to the oblong shape of our planet.

    The central magma of Mars is not liquid enough to create an electromagnetic field like Earth's. Some condition has cooled Mar's interior core. Probably the fact that it was whacked pretty hard during the last 100,000 years by a space chunk that was over 100 kilometers in size. It actually entered Mar's body and blew a "mons" out the other side of the planet. This, I imagine, would have had something to do with the cooling of Mar's core material.

    I suppose that Phobos and Eros(?), Mar's two moons, at one point did not present enough gravity to cause a tidal effect on Mar's oceanic bodies....... provided there ever were some.
  14. Jul 16, 2003 #13
    Thats an interesting observation regarding cooler stars and the probability of increased solar tides promoting life. A cooler star would give out less radiation which is now thought to be crucial for molecular mutation to occur but being closer to the star this problem is cancelled out. Being close to a small fire or far from a big fire gives equal radiation even at the stellar furnace level. Could such a planet retain an atmosphere though? Wouldn't the solar winds ablate it at such proximity? Maybe not. It's certainly an interesting idea. The sun would be the largest body in the system and therefore draw most of the debris such as dust, asteroids and comets. Gas giants act as vacuum cleaners to draw much of the outer system garbage but a terrestrial planet very close to a star might be bombarded by much of the rubble attracted by the sun. With smaller stars that could be a great deal more rubble. Or possible less. We keep rewriting planetary formation theories to keep up with new Hubble findings and exoplanet discoveries. Anyone know?
    Last edited: Jul 16, 2003
  15. Jul 18, 2003 #14


    User Avatar
    Gold Member

    The moon has numerous craters caused by meteorite collisions, and if there was no moon, many of those meteorites would have simply hit Earth; some of which could cause a castrophobic collision.

    Additionally, the moon has changed little (correct me if I'm wrong) ever since it was born, and has a very similar composition to the primordial Earth. I am uncertain about what I just said though, so please correct me if I'm wrong once again.

    I have watched an episode of the Discovery Channel which focused on why the Moon was so beneficial to the Earth; but I sadly lost my notes and am unable to consult it. :(
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook