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CelestialBody Protocol Reference
CelestialBody
public protocol CelestialBody : ObjectBaseBasic properties of an orbiting object. Used by solar system planets, and the Earth’ Moon, and the Sun.
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The radius vector (=distance to the Sun)
Declaration
Swift
var radiusVector: AstronomicalUnit { get } -
The coordinates of the object in the equatorial system (based on Earth equator).
Declaration
Swift
var equatorialCoordinates: EquatorialCoordinates { get } -
riseTransitSetTimes(for:Default implementation) Returns the Rise, Transit and Set times of the body for a given location on Earth.
Default Implementation
Returns the Rise, Transit and Set times of the body for a given location on Earth.
Declaration
Swift
func riseTransitSetTimes(for geographicCoordinates: GeographicCoordinates) -> RiseTransitSetTimesParameters
geographicCoordinatesThe coordinates of the location on Earth.
Return Value
A RiseTransitSetTimes object.
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hourAngle(for:Default implementation) Returns the Hour Angle of the celestial body, that is, the difference between its local mean sidereal time and its right ascension.
Default Implementation
Returns the Hour Angle of the celestial body, that is, the difference between its local mean sidereal time and its right ascension.
Declaration
Swift
func hourAngle(for geographicCoordinates: GeographicCoordinates) -> HourParameters
geographicCoordinatesThe geographic coordinates of the observer.
Return Value
The Hour Angle of the body.
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parallacticAngle(for:Default implementation) The parallactic angle is the angle between the direction of the zenith point relative the center of the disk, and that of the celestial north. The zenith point of the disk of a body (for instance, the Sun or the Moon) is the uppermost point of the disk at the sky as seen by the observer at a given instant. See Fig. 4, AA p.98. Exactly in zenith, the angle is not defined. When a celestial body passes exactly through the zenith, the parallactic angle suddenly jumps from -90º to 90º.
Default Implementation
Declaration
Swift
func parallacticAngle(for geographicCoordinates: GeographicCoordinates) -> DegreeParameters
geographicCoordinatesThe geographic coordinates of the observer.
Return Value
The angle in degrees.
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eclipticLongitudeOnHorizon(for:Default implementation) For a given location of the observer, the ecliptic plane cross that of the local horizontal plane, marking the horizon. Thus, one can compute the longitude of the two points of the ecliptic which are (180º appart) on the horizon.
Default Implementation
Declaration
Swift
func eclipticLongitudeOnHorizon(for geographicCoordinates: GeographicCoordinates) -> DegreeParameters
geographicCoordinatesThe geographic coordinates of the observer.
Return Value
The longitude of the ecliptic.
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angleBetweenEclipticAndHorizon(for:Default implementation) For a given location of the observer, the ecliptic plane cross that of the local horizontal plane, marking the horizon. Thus, one can compute the angle between the two planes.
Default Implementation
Declaration
Swift
func angleBetweenEclipticAndHorizon(for geographicCoordinates: GeographicCoordinates) -> DegreeParameters
geographicCoordinatesThe geographic coordinates of the observer.
Return Value
The angle between the ecliptic and the horizon.
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angleBetweenNorthCelestialPoleAndNorthPoleOfEcliptic(for:Default implementation) Undocumented
Default Implementation
Undocumented
Declaration
Swift
func angleBetweenNorthCelestialPoleAndNorthPoleOfEcliptic(for geographicCoordinates: GeographicCoordinates) -> Degree -
diurnalArcAngle(for:Default implementationgeographicCoordinates: ) The angle the Earth must make between the time at which the object is at a given altitude, then rotate, produce a diurnal arc, and reach a time at which the object reached again the same altitude. Basically, for the object being the Sun, and the altitude being 0=horizon, compute the angle between sunrise and sunset.
Default Implementation
The angle the Earth must make between the time at which the object is at a given altitude, then rotate, produce a diurnal arc, and reach a time at which the object reached again the same altitude. Basically, for the object being the Sun, and the altitude being 0=horizon, compute the angle between sunrise and sunset.
Declaration
Swift
func diurnalArcAngle(for objectAltitude: Degree, geographicCoordinates: GeographicCoordinates) -> (value: Degree?, error: CelestialBodyTransitError?)Parameters
objectAltitudeThe crossing altitude
geographicCoordinatesThe point on Earth from which one computes the arc.
Return Value
The angle of the so-called diurnal arc
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Geometric altitude (h0) of the center of the body at time of apparent rising or setting (see AA p.101)
Declaration
Swift
static var apparentRiseSetAltitude: Degree { get }