org.jeospace.physics.orbit
Class RotationalAxis

java.lang.Object
  org.jeospace.physics.orbit.RotationalAxis

public abstract class RotationalAxis

extends java.lang.Object

Utility class to obtain the rotational axis orientation of a world.

Note:This is a temporary placeholder for this functionality. The presumption is that the world is within the solar system and that the axis that is obtained from the world class is in Earth Equatorial coordinates. The coordinate is converted to ecliptic and the orientation is calculated relative to the ecliptic plane of the solar system.

Version:

$Revision: 1.1.1.1 $

Author:

Rex Melton

Constructor Summary

protected

RotationalAxis() Protected Constructor

Method Summary

static void	getOrientation(World world, double julianDay, float[] axisOrientation) Calculate the orientation of the axis rotational axis of the specified world .
static void	getRotationalAxisOrientation(Spherical axisDirection, float[] axisOrientation) Return the axis angle representation that will orient the axis of rotation of an ellipsoid toward the given Spherical coordinate on the celestial sphere.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RotationalAxis

protected RotationalAxis()

Protected Constructor

Method Detail

getOrientation

public static void getOrientation(World world,
                                  double julianDay,
                                  float[] axisOrientation)

Calculate the orientation of the axis rotational axis of the specified world .

Parameters:

world - the world to calculate the axis orientation for.

julianDay - the julian day on which to calculate the axis orientation.

axisOrientation - the array to initialize with the axis angle representation of the orientation.

getRotationalAxisOrientation

public static void getRotationalAxisOrientation(Spherical axisDirection,
                                                float[] axisOrientation)

Return the axis angle representation that will orient the axis of rotation of an ellipsoid toward the given Spherical coordinate on the celestial sphere.

The (ecliptic) axis direction gives us two values.

the longitude is the direction of the 'winter solstice' ( i.e. the direction in the parent system in which the equator of the child system is inclined directly away from the center.)

the latitude (subtracted from Math.PI/2) is the inclination of the equator to the plane of the system (the ecliptic).

Thus with these two values we can calculate the longitude of the vernal equinox ( i.e. the direction of zero longitude of the local equatorial coordinate system ) and the inclination of the equator of the local system to the reference orbital plane of the parent system (the ecliptic).

Parameters:

axisDirection - the Spherical object to convert

axisOrientation - the float array to initialize with the axis angle orientation