Planetary ring precession calculator by orbsi.uk

Calculates the apsidal precession rate of a particle orbiting in the equatorial plane around an oblate planet

Uses this equation (source: Elliot et al 1981 p447 equation 1)

G = SI units

M = kg

R = m

J2 =

J4 =

a = m

e =

i = 0 deg



G is the gravitational constant.
M is the mass of the planet.
R is the reference equatorial radius of the planet.
J2 and J4 are the dimensionless terms due to the planet's oblateness.
a is the semimajor axis of the particle orbit.
e is the eccentricity of the particle orbit.

The default parameters which appear at start-up are for Uranus and the midline of its epsilon ring,
source: French et al, in Bergstralh et al 1991 pages 327-409.

This calculator performs only simple validation of input, and therefore relies on the user to input realistic parameter values.

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