kspluto.h

/*
    SPDX-FileCopyrightText: 2001 Jason Harris <kstars@30doradus.org>
 
    SPDX-License-Identifier: GPL-2.0-or-later
*/
 
#ifndef KSPLUTO_H_
#define KSPLUTO_H_
 
#include "ksasteroid.h"
 
/** @class KSPluto
    *A subclass of KSAsteroid that represents the planet Pluto.  Now, we
    *are certainly NOT claiming that Pluto is an asteroid.  However, the
    *findPosition() routines of KSPlanet do not work properly for Pluto.
    *We had been using a unique polynomial expansion for Pluto, but even
    *this fails spectacularly for dates much more remote than a few
    *hundred years.  We consider it better to instead treat Pluto's
    *orbit much more simply, using elliptical orbital elements as we do
    *for asteroids.  In order to improve the long-term accuracy of Pluto's
    *position, we are also including linear approximations of the evolution
    *of each orbital element with time.
    *
    *The orbital element data (including the time-derivatives) come from
    *the NASA/JPL website:  https://ssd.jpl.nasa.gov/?planets#elem
    *
    *@short Provides necessary information about Pluto.
    *@author Jason Harris
    *@version 1.0
    */
 
class KSPluto : public KSAsteroid
{
  public:
    /** Constructor.  Calls KSAsteroid constructor with name="Pluto", and fills
            *in orbital element data (which is hard-coded for now).
            *@param fn filename of Pluto's image
            *@param pSize physical diameter of Pluto, in km
            */
    explicit KSPluto(const QString &fn = QString(), double pSize = 0);
 
    KSPluto *clone() const override;
 
    /**Destructor (empty) */
    ~KSPluto() override;
 
  protected:
    /** A custom findPosition() function for Pluto.  Computes the values of the
            *orbital elements on the requested date, and calls KSAsteroid::findGeocentricPosition()
            *using those elements.
            *@param num time-dependent values for the desired date
            *@param Earth planet Earth (needed to calculate geocentric coords)
            *@return true if position was successfully calculated.
            */
    bool findGeocentricPosition(const KSNumbers *num, const KSPlanetBase *Earth = nullptr) override;
 
  private:
    void findMagnitude(const KSNumbers *) override;
 
    //The base orbital elements for J2000 (these don't change with time)
    double a0, e0;
    dms i0, w0, M0, N0;
 
    //Rates-of-change for each orbital element
    double a1, e1, i1, w1, M1, N1;
};
 
#endif