Gyroscoop: Precessie

Precession can be explained by the gyroscopic motion of the Earth.

The counterclockwise spin of Earth creates an angular momentum. The Sun's gravitational force acting on Earth produces a torque perpendicular to the angular momentum and gravitational force.

Now, torque acting for time interval dt changes the direction of the angular momentum by dL. As the Earth is spinning, the direction of torque changes. Hence, the angular momentum constantly follows the torque, and precession occurs with velocity ω_P.

The precession velocity can be derived considering the torque acting on the system, which causes a change in angular momentum.

For a circular arc, the arc length divided by the radius is the change in precession angle. The rate of change of precession angle gives the precession velocity.

Now, substituting the value of dL, the precession velocity is inversely proportional to the angular momentum.

As angular momentum is the product of moment of inertia and angular velocity, precession velocity is inversely proportional to the angular velocity.