M

The Mean Anomaly indicates where the satellite was located within its orbit at a particular Epoch.

The Mean Anomaly at any time t, M(t), can be determined by adding the last known Mean Anomaly, M_o, to the orbit's Mean Motion multiplied by the time that has elapsed (t - t_o):

M(t) = M₀ + n (t - t₀)

where M(t) = the Mean Anomaly at time t;
           M₀ = the Mean Anomaly at t=0;
           n = the satellite orbit's Mean Motion;
           t = the time chosen; and
           t₀ = the time of the last known Mean Anomaly.

For a perfectly circular orbit (Eccentricity of 0), the Mean Anomaly is exactly equal to the True Anomaly throughout the orbit.

The Mean Anomaly is related to the Eccentric Anomaly (E) through Kepler's Equation.

The Mean Anomaly can range anywhere from 0 to 360 degrees.