public static Twilight getTwilight ( double sunDistanceRadians ) { double altDegrees = 90.0 - Math . toDegrees ( sunDistanceRadians ) ; if ( altDegrees >= 0.0 ) { return Twilight . DAYLIGHT ; } else if ( altDegrees >= - 6.0 ) { return Twilight . CIVIL ; } else if ( altDegrees >= - 12.0 ) { return Twilight . NAUTICAL ; } else if ( altDegrees >= - 18.0 ) { return Twilight . ASTRONOMICAL ; } return Twilight . NIGHT ; }
Return the twilight condition for a point which is a given great circle distance from the current sub solar point .