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Expanding universe and solar system

  1. Apr 3, 2009 #1
    I wonder how the expansion affected the solar system.

    Yes, I know that gravitationally bound objects had already "adapted" to the expansion. But it had adapted to the linear expansion - this assumption is valid only when we analyze a limited period of time.

    But the rate of the expansion changes, so there are 2nd degree effects which affect the gravitationally bound systems. Even without the dark energy, but the dark energy makes it even more interesting

    How big are these effects in the solar system during 4 billion years?
  2. jcsd
  3. Apr 3, 2009 #2


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    I don't have the numbers at hand, but the effect is quite accurately decribed by assuming a constant matter density (the critical) everywhere, with DE counting double negative. If the universe were homogeneous at small scales.
    But it isn't, and at our position there should be much dark matter, so orbits are indeed a little bit smaller than predicted by the gravity of baryonic matter (sun and planets and so on) alone.
  4. Apr 15, 2009 #3
    By solar system, I assume your mean our own sun and it's orbiting planets....

    Our solar system is too tiny to be affected by cosmological expansion....gravitational bounds are just too strong......that effect is observed over intergalatic, cosmological distances....far greater than our even own meager galaxy...
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