Why does the moon always have a dark side?

Discussion in 'Digital Cameras' started by Richard Henry, Apr 7, 2004.

  1. Richard Henry

    Alan Moore Guest


    Because there's only one sun, and it's a few million miles away from
    the moon.

    Al Moore
     
    Alan Moore, Apr 8, 2004
    #21
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  2. Dear ZZBunker:

    That's some good sh*t you're smoking there son. Be sure you don't answer
    the doorbell if it rings.

    David A. Smith
     
    N:dlzc D:aol T:com \(dlzc\), Apr 8, 2004
    #22
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  3. No, Mercury does *not* have a permanent dark side. It rotates on its axis in
    a period of 58.646 days, which is about 2/3rds of the time it takes to go
    around the sun (87.987 days). Its orbit is somewhat more elliptical than most
    planets, so the behavior of the sun's apparent motion as seen from the surface
    of Mercury gets a bit wierd at times, but all points on the surface (except
    perhaps in the shadows of some deep craters near the poles) will see the sun
    at some time during the Mercurian year. Clear skies to you.
    --
    David W. Knisely
    Prairie Astronomy Club: http://www.prairieastronomyclub.org
    Hyde Memorial Observatory: http://www.hydeobservatory.info/

    **********************************************
    * Attend the 11th Annual NEBRASKA STAR PARTY *
    * July 18-23, 2004, Merritt Reservoir *
    * http://www.NebraskaStarParty.org *
    **********************************************
     
    David Knisely, Apr 8, 2004
    #23
  4. Richard Henry

    CLT Guest

    CLT, Apr 9, 2004
    #24
  5. Richard Henry

    db Guest

    All planets, moons, astroids etc in our solar system always have a dark side.
    Because there's only one sun in our solar system.

    db
     
    db, Apr 10, 2004
    #25
  6. I asked fifty years ago and since, and have never received an answer,
    WHY the moon rotates exactly once per orbit round the earth? - Is it
    due to a heavy body within the moon that causes it to stay 'facing'
    us? - 'Dunno' is the usual answer, or 'Why not?' Similarly, the
    satellites always orbit in an equatorial plane, and in the same
    direction vis-a-vis rotation of the host - Look at Uranus (dch! the
    planet) - all in a tilted equatorial plane. It is understandable that
    what are now the planets were originally spun off the forming star by
    centrifugal force into an equatorial disk, and planetised from there,
    but do you think it possible that matter naturally is attracted
    gravitationally into such a path and in such a position? Remember
    that the stars, planets and their satellites are constantly hoovering
    up material from the space through which they travel, and it has to go
    somewhere. Is this position gravitationally most favoured for some
    reason, such as an aspect of precession perhaps?

    - Just asking.
     
    Justice international, Apr 11, 2004
    #26
  7. Richard Henry

    Paul H. Guest

    Go to http://www.nineplanets.org/luna.html , read carefully, and you will
    find the answer you seek. Your 50-year quest has come to an end and you may
    now move on to your final reward.
     
    Paul H., Apr 11, 2004
    #27
  8. What a cheek - 'final'! - Well, so long as you don't say 'rest'.

    Thanks anyway for the info. He says 'the bulge' is responsible for
    the 'facing us' factor, but it's more probably the offset core, or a
    combination of the two, as that would tend to put weight this side of
    its axis. And he doesn't mention the factor of same-way orbiting.
    But there are reasons for these things.

    Incidentally, I was also saying back then that there was obvious
    long-distance intergalactic repulsion, and blow me, a couple of years
    ago the chaps using Hubble were kind enough to say that it might
    actually exist. - If you will pardon a cosmological aspect rather than
    simply 'astro'.

    Thanks again. Nice group.
     
    Justice international, Apr 11, 2004
    #28
  9. Richard Henry

    Prometheus Guest

    The bulge is due to the gravitational attraction of the Earth (CF
    tides), the friction of this causes the Moon's axial rotation to slow
    but its orbital rotation increases (CF conservation of angular
    momentum). The tides that the Moon causes in the Earth will slow our
    axial speed until we have one face always towards the Moon. These
    transfers of angular momentum result in the Moon moving further away (CF
    Kepler), but don't worry this will take billions of years and the Sun
    will swell and swallow us first.
     
    Prometheus, Apr 11, 2004
    #29
  10. We live and learn. Thanks for the info. I have the quaint notion
    that the action you mention has 'already' happened, as the universe is
    already complete, but as we and our observation of it are part of the
    process of completion it necessarily seems to be incomplete and in
    'action'. - Just a notion, of course, and probably irrelevant here.
     
    Justice international, Apr 11, 2004
    #30
  11. Richard Henry

    per Guest

    It's an implicit function of yin and yang...
     
    per, Apr 11, 2004
    #31
  12. Richard Henry

    jmfbahciv Guest

    Typo. weeks.

    <snip>

    /BAH

    Subtract a hundred and four for e-mail.
     
    jmfbahciv, Apr 12, 2004
    #32
  13. Richard Henry

    Prometheus Guest

    It will not be complete before the last photon is absorbed by the last
    piece of rock, and even then the protons have to decay (assuming a
    non-collapsing.

    I am not sure what this has to do with photography, but since it might
    be wee you read it I have left that in.
     
    Prometheus, Apr 12, 2004
    #33
  14. Dunno what 'wee' means, other from little, or half of making water,
    but that apart, what the universe decrees as being complete and our
    opinion of what ought to be completed universe are very probably two
    completely different things. But nevertheless, if we see part of even
    an infinite universe, then the rest of it is already 'here'. We just
    can't see it, that's all. And if anyone wants to say that's just
    supposition, then that's alright by me.
     
    Justice international, Apr 12, 2004
    #34
  15. Richard Henry

    Prometheus Guest

    Typo, yes; "weeks", no; I meant "where"; 'weeks' does not fit!
     
    Prometheus, Apr 12, 2004
    #35
  16. Richard Henry

    jmfbahciv Guest

    Yep, my bad. I read it as "weeks since". I've been reading too
    many of that other guy's posts and got into a bad habit of filling
    in the b lanks.

    /BAH


    Subtract a hundred and four for e-mail.
     
    jmfbahciv, Apr 13, 2004
    #36
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