How do you calculate the angular velocity of precession?

1 Answer
Apr 8, 2016

The angular velocity vector of precession is normal to the Earth's orbital plane and its magnitude is the angular speed 50.2"/year, nearly.


Relative to the Earth's center, the poles move along parallel circles, parallel to (orbital plane of the Earth) the ecliptic, taking about a Great Year of 25800 Earth years, to complete the circle.

The radius of this circle = (polar radius of the Earth) X #sin 23.4^o#, nearly. The line joining the centers of this circle is normal to the ecliptic. This is the axis of revolution for the polar axis, for its precession motion

The angular speed of precession = #360^o#/(period of revolution in years) deg/year = #360/25800 = 0.01395^o#/year = 50.2"/year, nearly.

Importantly, the inclination of the polar axis to the normal to the ecliptic (tilt angle) remains the same #23.4^o#.