# Mean anomaly hyperbolic orbit

What does the mean anomaly mean in a hyperbolic orbit? How, knowing the mean anomalies at two points along the hyperbolic orbit, do you calculate the time to travel between the two points on the orbit? I know how to do this for elliptical orbits, but there is no orbital period for hyperbolic orbits.

The hyperbolic mean anomaly is defined by $$M = e\sinh H -H$$ This is very much analogous to the elliptical mean anomaly $$M = E - s\sin E$$
Just as the elliptical mean anomaly varies linearly with time, so does the hyperbolic mean anomaly. Just as the eccentric anomaly $E$ is related to the true anomaly $f$ via $$\tan\frac f 2 = \sqrt{\frac {1+e} {1-e}} \tan \frac E 2$$ the hyperbolic anomaly $H$ is related to the true anomaly $f$ via $$\tan\frac f 2 = \sqrt{\frac {e+1} {e-1}} \tanh \frac H 2$$