Celestial Body Class

CelestialBody.cs

/// <summary>
/// A celestial body that exists in a solar system
/// See http://www.stjarnhimlen.se/comp/ppcomp.html
/// </summary>
public abstract class CelestialBody
{
	/// <summary>
	/// The day number
	/// </summary>
	public static float d;

	/// <summary>
	/// longitude of the ascending node
	/// If you imagine the earth's orbit around the sun forming a plane, the ascending node is where a planet's orbit intersects that plane going "up".
	/// The longitude of that node, again imagining that plane of earth's orbit, is pretty much that node's direction as a Y-axis rotation.
	/// If this is a geocentric (earth-centric) celestial body, the plane we're talking about is actually Earth's equatorial plane instead (a plane bisecting the north and south hemispheres)
	/// </summary>
	public abstract float N { get; }

	/// <summary>
	/// inclination to the ecliptic (plane of the Earth's orbit)
	/// Basically, if you imagine an axis formed by the N angle, how much is the orbit rotated on that axis? 0 means orbit lies directly on the ecliptic.
	/// </summary>
	public abstract float i { get; }

	/// <summary>
	/// argument of perihelion
	/// Pretty much just a rotation around the ecliptic plane's up vector for the whole orbit
	/// </summary>
	public abstract float w { get; }

	/// <summary>
	/// semi-major axis, or mean distance from Sun (given in earth radii for the moon, but AU for the sun and other planets)
	/// Basically this is half the longest diameter of an ellipse
	/// </summary>
	public abstract float a { get; }

	/// <summary>
	/// eccentricity (0=circle, 0-1=ellipse, 1=parabola)
	/// </summary>
	public abstract float e { get; }

	/// <summary>
	/// current mean anomaly (0 at perihelion; increases uniformly with time)
	/// This is the angular distance from the start of orbit ("pericenter") that an object with a purely circular orbit with the same orbital period would have moved in the same time.
	/// </summary>
	public abstract float M { get; }

	/// <summary>
	/// obliquity of the ecliptic (the "tilt" of the Earth's axis of rotation)
	/// </summary>
	public float ecl
	{
		get { return 23.4393f - 3.563E-7f * d; }
	}

	/// <summary>
	/// whether this celestial body's calculations are relative to the sun
	/// </summary>
	public abstract bool IsHeliocentric { get; }
}