From what I have read and understood so far, the nodal precession of a satellite in low Earth orbit is caused by the bulge equatorial of the Earth (caused by its rotation on itself) which moves the force of attraction on a satellite towards the equator.

What I wonder is firstly, if the Earth is deformed by its rotation and therefore its diameter at the equator is greater than at the poles, is there more mass between a point on the surface at the equator and the center of the Earth or between a point on the surface of a pole (North or South) and the center of the earth?

And if there is more mass under the surface at the equator than at the poles, a satellite in low orbit will be subject to an attraction gravitational slightly stronger when it passes over the equator than at the poles which will participate in the nodal precession in addition from the explanation I gave above? Am I wrong?


1 Answer 1


I think you're talking about a radial effect? Nodal precession implies a torque, which a radial force cannot theoretically provide.

  • $\begingroup$ I wonder if there is more mass between the center and the surface at the Earth's equator and therefore if an orbiting satellite would experience a higher gravitational pull when passing over the equator than when passing above one of the two poles during its orbit? If so this would imply a radial force when the satellite is above the equator but when it is above a higher latitude during its orbit there would be a couple it seems to me? $\endgroup$ Commented Mar 5, 2023 at 19:21
  • $\begingroup$ @SebastyenLaroche en.wikipedia.org/wiki/Geopotential_model $\endgroup$
    – John Doty
    Commented Mar 5, 2023 at 20:22

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