/* Copyright 2002-2017 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
*
* This package provides interface to represent the position and geometry of
* space objects such as stars, planets or asteroids.
*
*<p>
* The position of celestial bodies is represented by the {@link
* org.orekit.bodies.CelestialBody} interface. This interface provides the methods
* needed to either consider the body as an external one for its gravity or lighting
* influence on spacecraft (typically in perturbing force computation) or as an internal
* one with its own frame.
*</p>
*
*<p>
* The {@link org.orekit.bodies.CelestialBodyFactory} class is a factory providing several
* predefined instances implementing the {@link org.orekit.bodies.CelestialBody}
* interface for the main solar system bodies. The Sun, the Moon, the eight planets and
* the Pluto dwarf planet are the supported bodies. In addition to these real bodies,
* two points are supported for convenience as if they were real bodies: the solar system
* barycenter and the Earth-Moon barycenter. The {@link org.orekit.bodies.CelestialBodyFactory}
* factory relies on the JPL DE 405, 406 or similar binary ephemerides files to compute all
* positions and velocities. Note that the binary files are used, not the ASCII ones,
* regardless of the processor endianness.
*</p>
*
*<p>
* As an example, computing the position of the Sun and the Moon in the EME2000 frame,
* this done as follows:
*</p>
*
*<pre>
* CelestialBody sun = CelestialBodyFactory.getSun();
* CelestialBody moon = CelestialBodyFactory.getMoon();
* Vector3D sunInEME2000 = sun.getPVCoordinates(date, Frame.getEME2000()).getPosition();
* Vector3D moonInEME2000 = moon.getPVCoordinates(date, Frame.getEME2000()).getPosition();
*</pre>
*
*<p>
* Since the supported bodies implement the {@link org.orekit.bodies.CelestialBody}
* interface, they all provide their own body-centered inertial frame, hence adding a few
* more frames to the ones provided by the {@link org.orekit.frames} package. Since the
* frames tree is rooted at an Earth-centered frame, the solar system bodies frames tree
* does not seems in canonical shape. This of course is only a side effect of the
* arbitrary choice of GCRF as the root frame and has no effect at all on computations.
*</p>
*
*<p>
* The shape of celestial bodies is represented by the {@link org.orekit.bodies.BodyShape}
* interface.
*</p>
*
*<p>
* Only one implementation is provided by OREKIT for now: the {@link
* org.orekit.bodies.OneAxisEllipsoid} class which represents the natural flattened shape
* of big space rotating bodies like planets or the Sun.
*</p>
*
*<p>
* For asteroids, it is expected that users provide their own shape models, for example
* based on triangulation. They should implement the {@link org.orekit.bodies.BodyShape}
* interface in order to be used by Orekit.
*</p>
*
*<p>
* When using {@link org.orekit.bodies.OneAxisEllipsoid} body representation, points are
* generally described in associated body frame, by so-called <i>geodetic</i> coordinates
* (longitude, latitude, altitude). The {@link org.orekit.bodies.GeodeticPoint} class allows
* handling of such coordinates. It is a simple container that does not provide processing
* methods.
*</p>
*
*@author L. Maisonobe
*
*/
package org.orekit.bodies;