I know that precession appears when the axis of rotation of the planet is not perpendicular to the plane of the satellite's orbit and tidal forces applied to the equatorial belt tend to rotate the planet's axis of rotation. However I can't really understand why is it that Earth spins to the east and it's axis to the west:

enter image description here

For example, top's precession goes to the same direction to which it spins:

enter image description here

Could somebody please provide an explanation?

  • $\begingroup$ This would be explained if the direction of the torques were opposite, unlike in the diagram (Where did you get it?). The Wikipedia article explains how the torque on the Earth is generated, although it does not explicitly discuss the direction. My impression is that tidal forces are "trying" to make the spin axis perpendicular to the orbital plane, which would mean the opposite sign of torque to the top. $\endgroup$ Sep 5, 2021 at 17:45
  • $\begingroup$ Did you get the image from spark.iop.org/precession $\endgroup$
    – James K
    Sep 5, 2021 at 19:39
  • $\begingroup$ Analytically I don't know but for the spinning top the perturbation is weight. For the Earth we have a different scenario. $\endgroup$
    – Alchimista
    Sep 8, 2021 at 10:02
  • $\begingroup$ Could you describe it in more details? $\endgroup$
    – ALiCe P.
    Sep 10, 2021 at 9:34

1 Answer 1


I think I figured that out. At point 1 the torque vector is directed to the observer and at point 2 - from observed perpendicular to the plane of the drawing according to the right hand rule. All this makes the axis rotate clockwise while the Earth rotates counterclockwise.

enter image description here


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