off topic can someone answer him

From: Cynthia (
Date: Sat Nov 05 2005 - 17:43:40 EST

  • Next message: "Questions about breakups and rocket bodies"

    Three answers to your question, Chris....
    From the Fort Bend Astronomy Club (FBAC)
    Houston, Texas
    -----Original Message-----
    From: []
    On Behalf Of Bill Dillon
    Sent: Saturday, November 05, 2005 3:44 PM
    Subject: Re: [FBAC] FW: can someone answer this question?
    Well, in the real world, there is no such thing as perfect, uniform 
    density, so in a practical sense, I think Hal is correct.
    Even if one could have such a perfect sphere, I can think of two effects 
    that would put a torque (force imbalance) on the sphere and start it 
    The first is the pressure gradient in the earth's atmosphere.  The 
    earth's atmosphere never really stops, it just keeps getting thinner 
    with altitude.  The side of the satellite closest to the earth is 
    experiencing an ever so slightly greater drag force.  This would start 
    the satellite spinning on an axis perpendicular to a line pointing to 
    the center of the earth and it's direction of motion (RxV).
    The second torque comes from "frame dragging", an effect predicted by 
    Einstein's General Theory of Relativity when you're in orbit about a 
    spinning mass.  Gravity Probe B is currently testing for this affect.  See:
    Dave Morrell wrote:
    > If the satellite were a perfect sphere of uniform density I don't think 
    > the orbital motion would have any effect on its rotation.
    > At 10:14 AM 11/5/2005, you wrote:
    >> I would guess that over time eventually one face would be constantly 
    >> pointed toward the Earth, like the Moon, due to tidal forces slowing 
    >> any rotation of the satellite.  The satellite would then be rotating 
    >> once per orbit.
    >> Hal Coward
    >> ----- Original Message -----
    >> From: <>Cynthia
    >> To: <>
    >> Sent: Saturday, November 05, 2005 10:06 AM
    >> Subject: [FBAC] FW: can someone answer this question?
    >> Anyone want to take a stab at this?
    >> Answer to <>
    >> -----Original Message-----
    >> From: Kevin Fetter []
    >> Sent: Friday, November 04, 2005 9:01 PM
    >> To: <>
    >> Subject: off topic can someone answer him
    >> I was asked this question
    >> If a perfectly spherical sattelite orbits the earth in any given 
    >> orbit, will
    >> the satellite rotate as it orbits the earth?
    >> I would think over time, because of various forces acting on it, it would
    >> start to rotate. But I wish to see what people with way more interest in
    >> theory's think.
    >> His email is <>
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