code: static final double moonAge(long time)
      {
          double age = 0;
  
          synchronized(astro) {
              astro.setTime(time);
              age = astro.getMoonAge();
          }
          // Convert to degrees and normalize...
          age = age * 180 / Math.PI;
          if (age > 180) {
              age = age - 360;
          }
  
          return age;
      }
docs: Return the "age" of the moon at the given time; this is the difference
  in ecliptic latitude between the moon and the sun.  This method simply
  calls CalendarAstronomer.moonAge, converts to degrees,
  and adjusts the resultto be in the range [-180, 180].
  
  @param time  The time at which the moon's age is desired,
  in millis since 1/1/1970.