//Returns the next time at which the orbiting object will cross the equator
//moving southward, if o is east-moving, or northward, if o is west-moving.
//For elliptical orbits this is a time between UT and UT + o.period.
//For hyperbolic orbits this can by any time, including a time in the past if the
//descending node is in the past.
//NOTE: this function will throw an ArgumentException if o is a hyperbolic orbit and the
//"descending node" occurs at a true anomaly that o does not actually ever attain.
public static double TimeOfDescendingNodeEquatorial(this Orbit o, double UT)
{
return(o.TimeOfTrueAnomaly(o.DescendingNodeEquatorialTrueAnomaly(), UT));
}
//Returns whether o has a descending node with the equator. This can be false
//if o is hyperbolic and the would-be descending node is within the opening
//angle of the hyperbola.
public static bool DescendingNodeEquatorialExists(this Orbit o)
{
return(Math.Abs(MuUtils.ClampDegrees180(o.DescendingNodeEquatorialTrueAnomaly())) <= o.MaximumTrueAnomaly());
}
