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Stargazing Question about orbiting

  1. Sep 24, 2016 #1
    hello,
    i can't seem to find answer in my country forum, so I ask here, hope you don't mind

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    (1)
    Is it possible for planet to have 2 moon orbit in crossing pattern?
    like... one orbit around equator another orbit around north and south pole


    (2)
    Can multiple moon orbit in parallel pattern?
    like.... one orbit around equator, one orbit around northern hemisphere, and another orbit around southern hemisphere.

    (3)
    Can 2 moon share same orbit but directly opposite to each other?

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    thank you in advance for the answer.
    oh and... English is not my native language, forgive me if I'm wrong in spelling or grammar.
     
  2. jcsd
  3. Sep 24, 2016 #2

    mathman

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    Science Advisor
    Gold Member

    (1) yes - be careful so they don't collide
    (2) no - orbits are around center of mass of system, usually center of planet (assumed much larger than moon)
    (3) yes
     
  4. Sep 25, 2016 #3
    so, I presume that planet direction of rotation have nothing to do with orbiting?
     
  5. Sep 25, 2016 #4
    That depends. As this Wikipedia entry explains: "If formed in the gravity-field of a planet as the planet is forming, a moon will orbit the planet in the same direction as the planet is rotating and is a regular moon. If an object is formed elsewhere and later captured into orbit by a planet's gravity, it can be captured into a retrograde or prograde orbit depending on whether it first approaches the side of the planet that is rotating towards or away from it. This is an irregular moon."
    https://en.wikipedia.org/wiki/Retrograde_and_prograde_motion
     
  6. Sep 25, 2016 #5

    Bandersnatch

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    Science Advisor

    However, it should be noted that both 1 and 3 are unstable orbits, unless both orbiting bodies have negligibly small masses. That is, you can't have large moons in these configurations.
     
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