      
      - returns: A length in (Julian) Days.
      */
-    func lengthOfSeason(_ season: Season, northernHemisphere: Bool) -> Day {
+    public func lengthOfSeason(_ season: Season, northernHemisphere: Bool) -> Day {
         let year = self.julianDay.date.year
         switch season {
         case .spring:

     
     - returns: A julian day of the TT time of the equinox.
     */
    func equinox(of equinoxType: EarthEquinoxType) -> JulianDay {
        let year = self.julianDay.date.year
        switch equinoxType {
        case .northwardSpring:

     
     - returns: A julian day of the TT time of the solstice.
     */
    public func solstice(of solsticeType: EarthSolsticeType) -> JulianDay {
        let year = self.julianDay.date.year
        switch solsticeType {
        case .northernSummer:
