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nofxx/moon.rb

Created August 31, 2009 02:14
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Revisions

  1. nofxx revised this gist Sep 7, 2009. 1 changed file with 52 additions and 23 deletions.
    75 changes: 52 additions & 23 deletions moon.rb
    View file
    Original file line number Diff line number Diff line change
    @@ -1,37 +1,56 @@
    #
    # Lunar/Moon phases ruby class
    #
    # Code is based upon Bradley E. Schaefer''s moon phase algorithm.
    # Ruby version based on JavaScript Phase Calculator by Stephen R. Schmitt
    class Moon
    attr_reader :epoch, :phase, :days
    attr_reader :epoch, :phase, :days, :icon, :dist, :ll

    # Return the current (or input a date) moon
    # Return the current (or input a date) moon.
    # Moon.new
    # Moon.new(some_day)
    #
    # Methods available:
    # phase => Phase of the moon as a sym
    # days => Moon days
    # icon => An integer from 0 to 29
    # dist => Distance in earth radii
    # ll => Moon ecliptic lat/lon
    #
    def initialize(epoch=Time.now)
    @epoch = epoch
    @phase = calculate_phase
    @days = calculate_days
    do_calc
    end

    private

    def calculate_days
    (do_calc * 100).to_i / 100
    def calc_phase(p)
    case p
    when 0 then :new
    when 1..6 then :waxing_crescent
    when 7..9 then :first_quarter
    when 10..12 then :waxing_gibbous
    when 13..16 then :full
    when 17..20 then :waning_gibbous
    when 21..24 then :last_quarter
    when 25..28 then :waning_crescent
    else :new
    end
    end

    def calculate_phase
    t_phase = do_calc.to_i % 30
    case t_phase
    when 0 then :new
    when 1..6 then :waxing_crescent
    when 7 then :first_quarter
    when 8..14 then :waxing_gibbous
    when 15 then :full
    when 16..22 then :waning_gibbous
    when 23 then :last_quarter
    else :waning_crescent
    end
    def calc_coords(inter, phase)
    phase = phase * 2 * Math::PI
    dp = 2 * Math::PI * normalize((inter - 2451562.2 ) / 27.55454988)
    @dist = 60.4 - 3.3 * Math.cos(dp) - 0.6 * Math.cos(2 * phase - dp) - 0.5 * Math.cos(2 * phase)

    np = 2 * Math::PI * normalize((inter - 2451565.2) / 27.212220817)
    la = 5.1 * Math.sin(np)

    rp = normalize((inter - 2451555.8 ) / 27.321582241)
    lo = 360 * rp + 6.3 * Math.sin(dp) + 1.3 * Math.sin(2 * phase - dp) + 0.7 * Math.sin(2 * phase)
    @ll = [la, lo]
    end

    # Code is based upon Bradley E. Schaefer''s moon phase algorithm.
    def do_calc
    c_phase = 29.530588853
    t_year = @epoch.year - ((12 - @epoch.month)/10).to_i
    @@ -40,11 +59,21 @@ def do_calc
    t1 = (365.25 * (t_year + 4712)).to_i
    t2 = (30.6 * t_month + 0.5).to_i
    t3 = (((t_year / 100.0) + 49.0) * 0.75).to_i - 38
    inter = t1 + t2 + (@epoch.day + (@epoch.hour - 1) / 24.0).to_i + 59
    inter = t1 + t2 + @epoch.day + 59
    inter -= t3 if inter > 2299160
    phase = (inter - 2451550.1) / c_phase % 1
    phase += 1 if phase < 0
    phase * c_phase;
    phase = normalize((inter - 2451550.1) / c_phase)
    res = phase * c_phase;

    @days = (res * 100).to_i / 100
    @icon = res.to_i % 30
    @phase = calc_phase(@icon)
    calc_coords(inter, phase)
    end

    def normalize(x)
    x %= 1
    x += 1 if x < 0
    x
    end

    end
  2. nofxx created this gist Aug 31, 2009.
    50 changes: 50 additions & 0 deletions moon.rb
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,50 @@
    #
    # Lunar/Moon phases ruby class
    #
    class Moon
    attr_reader :epoch, :phase, :days

    # Return the current (or input a date) moon
    def initialize(epoch=Time.now)
    @epoch = epoch
    @phase = calculate_phase
    @days = calculate_days
    end

    private

    def calculate_days
    (do_calc * 100).to_i / 100
    end

    def calculate_phase
    t_phase = do_calc.to_i % 30
    case t_phase
    when 0 then :new
    when 1..6 then :waxing_crescent
    when 7 then :first_quarter
    when 8..14 then :waxing_gibbous
    when 15 then :full
    when 16..22 then :waning_gibbous
    when 23 then :last_quarter
    else :waning_crescent
    end
    end

    # Code is based upon Bradley E. Schaefer''s moon phase algorithm.
    def do_calc
    c_phase = 29.530588853
    t_year = @epoch.year - ((12 - @epoch.month)/10).to_i
    t_month = (@epoch.month + 9) % 12

    t1 = (365.25 * (t_year + 4712)).to_i
    t2 = (30.6 * t_month + 0.5).to_i
    t3 = (((t_year / 100.0) + 49.0) * 0.75).to_i - 38
    inter = t1 + t2 + (@epoch.day + (@epoch.hour - 1) / 24.0).to_i + 59
    inter -= t3 if inter > 2299160
    phase = (inter - 2451550.1) / c_phase % 1
    phase += 1 if phase < 0
    phase * c_phase;
    end

    end