moonphase.cs

using System;
using System.Linq;
using demo_helper;
using CosineKitty;

namespace moonphase
{
    class Program
    {
        static string QuarterName(int quarter)
        {
            switch (quarter)
            {
                case 0: return "New Moon";
                case 1: return "First Quarter";
                case 2: return "Full Moon";
                case 3: return "Third Quarter";
                default: return "INVALID QUARTER";
            }
        }

        static int Main(string[] args)
        {
            AstroTime time;
            switch (args.Length)
            {
                case 0:
                    time = new AstroTime(DateTime.Now);
                    break;

                case 1:
                    time = DemoHelper.ParseTime("moonphase", args[0]);
                    break;

                default:
                    Console.WriteLine("USAGE: moonphase [date]");
                    return 1;
            }

            /*
                Calculate the Moon's ecliptic phase angle,
                which ranges from 0 to 360 degrees.

                0 = new moon,
                90 = first quarter,
                180 = full moon,
                270 = third quarter.
            */
            double phase = Astronomy.MoonPhase(time);
            Console.WriteLine("{0} : Moon's ecliptic phase angle = {1:F3} degrees.", time, phase);

            /*
                Calculate the percentage of the Moon's disc that is illuminated
                from the Earth's point of view.
            */
            IllumInfo illum = Astronomy.Illumination(Body.Moon, time);
            Console.WriteLine("{0} : Moon's illuminated fraction = {1:F2}%.", time, 100.0 * illum.phase_fraction);

            /* Find the next 10 lunar quarter phases. */
            Console.WriteLine();
            Console.WriteLine("The next 10 lunar quarters are:");
            foreach (MoonQuarterInfo mq in Astronomy.MoonQuartersAfter(time).Take(10))
                Console.WriteLine("{0} : {1}", mq.time, QuarterName(mq.quarter));

            return 0;
        }
    }
}