1;;; lunar.el --- calendar functions for phases of the moon 2 3;; Copyright (C) 1992, 1993, 1995, 1997, 2001, 2002, 2003, 2004, 2005, 4;; 2006, 2007 Free Software Foundation, Inc. 5 6;; Author: Edward M. Reingold <reingold@cs.uiuc.edu> 7;; Maintainer: Glenn Morris <rgm@gnu.org> 8;; Keywords: calendar 9;; Human-Keywords: moon, lunar phases, calendar, diary 10 11;; This file is part of GNU Emacs. 12 13;; GNU Emacs is free software; you can redistribute it and/or modify 14;; it under the terms of the GNU General Public License as published by 15;; the Free Software Foundation; either version 2, or (at your option) 16;; any later version. 17 18;; GNU Emacs is distributed in the hope that it will be useful, 19;; but WITHOUT ANY WARRANTY; without even the implied warranty of 20;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21;; GNU General Public License for more details. 22 23;; You should have received a copy of the GNU General Public License 24;; along with GNU Emacs; see the file COPYING. If not, write to the 25;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 26;; Boston, MA 02110-1301, USA. 27 28;;; Commentary: 29 30;; This collection of functions implements lunar phases for calendar.el and 31;; diary.el. 32 33;; Based on ``Astronomical Formulae for Calculators,'' 3rd ed., by Jean Meeus, 34;; Willmann-Bell, Inc., 1985 and ``Astronomical Algorithms'' by Jean Meeus, 35;; Willmann-Bell, Inc., 1991. 36;; 37;; WARNING: The calculations will be accurate only to within a few minutes. 38 39;; The author would be delighted to have an astronomically more sophisticated 40;; person rewrite the code for the lunar calculations in this file! 41 42;; Technical details of all the calendrical calculations can be found in 43;; ``Calendrical Calculations: The Millennium Edition'' by Edward M. Reingold 44;; and Nachum Dershowitz, Cambridge University Press (2001). 45 46;;; Code: 47 48(defvar date) 49(defvar displayed-month) 50(defvar displayed-year) 51 52(if (fboundp 'atan) 53 (require 'lisp-float-type) 54 (error "Lunar calculations impossible since floating point is unavailable")) 55 56(require 'solar) 57 58(defun lunar-phase-list (month year) 59 "List of lunar phases for three months starting with Gregorian MONTH, YEAR." 60 (let ((end-month month) 61 (end-year year) 62 (start-month month) 63 (start-year year)) 64 (increment-calendar-month end-month end-year 3) 65 (increment-calendar-month start-month start-year -1) 66 (let* ((end-date (list (list end-month 1 end-year))) 67 (start-date (list (list start-month 68 (calendar-last-day-of-month 69 start-month start-year) 70 start-year))) 71 (index (* 4 72 (truncate 73 (* 12.3685 74 (+ year 75 ( / (calendar-day-number (list month 1 year)) 76 366.0) 77 -1900))))) 78 (new-moon (lunar-phase index)) 79 (list)) 80 (while (calendar-date-compare new-moon end-date) 81 (if (calendar-date-compare start-date new-moon) 82 (setq list (append list (list new-moon)))) 83 (setq index (1+ index)) 84 (setq new-moon (lunar-phase index))) 85 list))) 86 87(defun lunar-phase (index) 88 "Local date and time of lunar phase INDEX. 89Integer below INDEX/4 gives the lunation number, counting from Jan 1, 1900; 90remainder mod 4 gives the phase: 0 new moon, 1 first quarter, 2 full moon, 913 last quarter." 92 (let* ((phase (mod index 4)) 93 (index (/ index 4.0)) 94 (time (/ index 1236.85)) 95 (date (+ (calendar-absolute-from-gregorian '(1 0.5 1900)) 96 0.75933 97 (* 29.53058868 index) 98 (* 0.0001178 time time) 99 (* -0.000000155 time time time) 100 (* 0.00033 101 (solar-sin-degrees (+ 166.56 102 (* 132.87 time) 103 (* -0.009173 time time)))))) 104 (sun-anomaly (mod 105 (+ 359.2242 106 (* 29.105356 index) 107 (* -0.0000333 time time) 108 (* -0.00000347 time time time)) 109 360.0)) 110 (moon-anomaly (mod 111 (+ 306.0253 112 (* 385.81691806 index) 113 (* 0.0107306 time time) 114 (* 0.00001236 time time time)) 115 360.0)) 116 (moon-lat (mod 117 (+ 21.2964 118 (* 390.67050646 index) 119 (* -0.0016528 time time) 120 (* -0.00000239 time time time)) 121 360.0)) 122 (adjustment 123 (if (memq phase '(0 2)) 124 (+ (* (- 0.1734 (* 0.000393 time)) 125 (solar-sin-degrees sun-anomaly)) 126 (* 0.0021 (solar-sin-degrees (* 2 sun-anomaly))) 127 (* -0.4068 (solar-sin-degrees moon-anomaly)) 128 (* 0.0161 (solar-sin-degrees (* 2 moon-anomaly))) 129 (* -0.0004 (solar-sin-degrees (* 3 moon-anomaly))) 130 (* 0.0104 (solar-sin-degrees (* 2 moon-lat))) 131 (* -0.0051 (solar-sin-degrees (+ sun-anomaly moon-anomaly))) 132 (* -0.0074 (solar-sin-degrees (- sun-anomaly moon-anomaly))) 133 (* 0.0004 (solar-sin-degrees (+ (* 2 moon-lat) sun-anomaly))) 134 (* -0.0004 (solar-sin-degrees (- (* 2 moon-lat) sun-anomaly))) 135 (* -0.0006 (solar-sin-degrees 136 (+ (* 2 moon-lat) moon-anomaly))) 137 (* 0.0010 (solar-sin-degrees (- (* 2 moon-lat) moon-anomaly))) 138 (* 0.0005 (solar-sin-degrees 139 (+ (* 2 moon-anomaly) sun-anomaly)))) 140 (+ (* (- 0.1721 (* 0.0004 time)) 141 (solar-sin-degrees sun-anomaly)) 142 (* 0.0021 (solar-sin-degrees (* 2 sun-anomaly))) 143 (* -0.6280 (solar-sin-degrees moon-anomaly)) 144 (* 0.0089 (solar-sin-degrees (* 2 moon-anomaly))) 145 (* -0.0004 (solar-sin-degrees (* 3 moon-anomaly))) 146 (* 0.0079 (solar-sin-degrees (* 2 moon-lat))) 147 (* -0.0119 (solar-sin-degrees (+ sun-anomaly moon-anomaly))) 148 (* -0.0047 (solar-sin-degrees (- sun-anomaly moon-anomaly))) 149 (* 0.0003 (solar-sin-degrees (+ (* 2 moon-lat) sun-anomaly))) 150 (* -0.0004 (solar-sin-degrees (- (* 2 moon-lat) sun-anomaly))) 151 (* -0.0006 (solar-sin-degrees (+ (* 2 moon-lat) moon-anomaly))) 152 (* 0.0021 (solar-sin-degrees (- (* 2 moon-lat) moon-anomaly))) 153 (* 0.0003 (solar-sin-degrees 154 (+ (* 2 moon-anomaly) sun-anomaly))) 155 (* 0.0004 (solar-sin-degrees 156 (- sun-anomaly (* 2 moon-anomaly)))) 157 (* -0.0003 (solar-sin-degrees 158 (+ (* 2 sun-anomaly) moon-anomaly)))))) 159 (adj (+ 0.0028 160 (* -0.0004 (solar-cosine-degrees 161 sun-anomaly)) 162 (* 0.0003 (solar-cosine-degrees 163 moon-anomaly)))) 164 (adjustment (cond ((= phase 1) (+ adjustment adj)) 165 ((= phase 2) (- adjustment adj)) 166 (t adjustment))) 167 (date (+ date adjustment)) 168 (date (+ date (/ (- calendar-time-zone 169 (solar-ephemeris-correction 170 (extract-calendar-year 171 (calendar-gregorian-from-absolute 172 (truncate date))))) 173 60.0 24.0))) 174 (time (* 24 (- date (truncate date)))) 175 (date (calendar-gregorian-from-absolute (truncate date))) 176 (adj (dst-adjust-time date time))) 177 (list (car adj) (apply 'solar-time-string (cdr adj)) phase))) 178 179(defun lunar-phase-name (phase) 180 "Name of lunar PHASE. 1810 = new moon, 1 = first quarter, 2 = full moon, 3 = last quarter." 182 (cond ((= 0 phase) "New Moon") 183 ((= 1 phase) "First Quarter Moon") 184 ((= 2 phase) "Full Moon") 185 ((= 3 phase) "Last Quarter Moon"))) 186 187(defun calendar-phases-of-moon () 188 "Create a buffer with the lunar phases for the current calendar window." 189 (interactive) 190 (message "Computing phases of the moon...") 191 (let ((m1 displayed-month) 192 (y1 displayed-year) 193 (m2 displayed-month) 194 (y2 displayed-year)) 195 (increment-calendar-month m1 y1 -1) 196 (increment-calendar-month m2 y2 1) 197 (set-buffer (get-buffer-create lunar-phases-buffer)) 198 (setq buffer-read-only nil) 199 (calendar-set-mode-line 200 (if (= y1 y2) 201 (format "Phases of the Moon from %s to %s, %d%%-" 202 (calendar-month-name m1) (calendar-month-name m2) y2) 203 (format "Phases of the Moon from %s, %d to %s, %d%%-" 204 (calendar-month-name m1) y1 (calendar-month-name m2) y2))) 205 (erase-buffer) 206 (insert 207 (mapconcat 208 '(lambda (x) 209 (let ((date (car x)) 210 (time (car (cdr x))) 211 (phase (car (cdr (cdr x))))) 212 (concat (calendar-date-string date) 213 ": " 214 (lunar-phase-name phase) 215 " " 216 time))) 217 (lunar-phase-list m1 y1) "\n")) 218 (goto-char (point-min)) 219 (set-buffer-modified-p nil) 220 (setq buffer-read-only t) 221 (display-buffer lunar-phases-buffer) 222 (message "Computing phases of the moon...done"))) 223 224;;;###autoload 225(defun phases-of-moon (&optional arg) 226 "Display the quarters of the moon for last month, this month, and next month. 227If called with an optional prefix argument, prompts for month and year. 228 229This function is suitable for execution in a .emacs file." 230 (interactive "P") 231 (save-excursion 232 (let* ((date (if arg 233 (calendar-read-date t) 234 (calendar-current-date))) 235 (displayed-month (extract-calendar-month date)) 236 (displayed-year (extract-calendar-year date))) 237 (calendar-phases-of-moon)))) 238 239(defun diary-phases-of-moon (&optional mark) 240"Moon phases diary entry. 241 242An optional parameter MARK specifies a face or single-character string to 243use when highlighting the day in the calendar." 244 (let* ((index (* 4 245 (truncate 246 (* 12.3685 247 (+ (extract-calendar-year date) 248 ( / (calendar-day-number date) 249 366.0) 250 -1900))))) 251 (phase (lunar-phase index))) 252 (while (calendar-date-compare phase (list date)) 253 (setq index (1+ index)) 254 (setq phase (lunar-phase index))) 255 (if (calendar-date-equal (car phase) date) 256 (cons mark (concat (lunar-phase-name (car (cdr (cdr phase)))) " " 257 (car (cdr phase))))))) 258 259 260;; For the Chinese calendar the calculations for the new moon need to be more 261;; accurate than those above, so we use more terms in the approximation. 262 263(defun lunar-new-moon-time (k) 264 "Astronomical (Julian) day number of K th new moon." 265 (let* ((T (/ k 1236.85)) 266 (T2 (* T T)) 267 (T3 (* T T T)) 268 (T4 (* T2 T2)) 269 (JDE (+ 2451550.09765 270 (* 29.530588853 k) 271 (* 0.0001337 T2) 272 (* -0.000000150 T3) 273 (* 0.00000000073 T4))) 274 (E (- 1 (* 0.002516 T) (* 0.0000074 T2))) 275 (sun-anomaly (+ 2.5534 276 (* 29.10535669 k) 277 (* -0.0000218 T2) 278 (* -0.00000011 T3))) 279 (moon-anomaly (+ 201.5643 280 (* 385.81693528 k) 281 (* 0.0107438 T2) 282 (* 0.00001239 T3) 283 (* -0.000000058 T4))) 284 (moon-argument (+ 160.7108 285 (* 390.67050274 k) 286 (* -0.0016341 T2) 287 (* -0.00000227 T3) 288 (* 0.000000011 T4))) 289 (omega (+ 124.7746 290 (* -1.56375580 k) 291 (* 0.0020691 T2) 292 (* 0.00000215 T3))) 293 (A1 (+ 299.77 (* 0.107408 k) (* -0.009173 T2))) 294 (A2 (+ 251.88 (* 0.016321 k))) 295 (A3 (+ 251.83 (* 26.641886 k))) 296 (A4 (+ 349.42 (* 36.412478 k))) 297 (A5 (+ 84.66 (* 18.206239 k))) 298 (A6 (+ 141.74 (* 53.303771 k))) 299 (A7 (+ 207.14 (* 2.453732 k))) 300 (A8 (+ 154.84 (* 7.306860 k))) 301 (A9 (+ 34.52 (* 27.261239 k))) 302 (A10 (+ 207.19 (* 0.121824 k))) 303 (A11 (+ 291.34 (* 1.844379 k))) 304 (A12 (+ 161.72 (* 24.198154 k))) 305 (A13 (+ 239.56 (* 25.513099 k))) 306 (A14 (+ 331.55 (* 3.592518 k))) 307 (correction 308 (+ (* -0.40720 (solar-sin-degrees moon-anomaly)) 309 (* 0.17241 E (solar-sin-degrees sun-anomaly)) 310 (* 0.01608 (solar-sin-degrees (* 2 moon-anomaly))) 311 (* 0.01039 (solar-sin-degrees (* 2 moon-argument))) 312 (* 0.00739 E (solar-sin-degrees (- moon-anomaly sun-anomaly))) 313 (* -0.00514 E (solar-sin-degrees (+ moon-anomaly sun-anomaly))) 314 (* 0.00208 E E (solar-sin-degrees (* 2 sun-anomaly))) 315 (* -0.00111 (solar-sin-degrees 316 (- moon-anomaly (* 2 moon-argument)))) 317 (* -0.00057 (solar-sin-degrees 318 (+ moon-anomaly (* 2 moon-argument)))) 319 (* 0.00056 E (solar-sin-degrees 320 (+ (* 2 moon-anomaly) sun-anomaly))) 321 (* -0.00042 (solar-sin-degrees (* 3 moon-anomaly))) 322 (* 0.00042 E (solar-sin-degrees 323 (+ sun-anomaly (* 2 moon-argument)))) 324 (* 0.00038 E (solar-sin-degrees 325 (- sun-anomaly (* 2 moon-argument)))) 326 (* -0.00024 E (solar-sin-degrees 327 (- (* 2 moon-anomaly) sun-anomaly))) 328 (* -0.00017 (solar-sin-degrees omega)) 329 (* -0.00007 (solar-sin-degrees 330 (+ moon-anomaly (* 2 sun-anomaly)))) 331 (* 0.00004 (solar-sin-degrees 332 (- (* 2 moon-anomaly) (* 2 moon-argument)))) 333 (* 0.00004 (solar-sin-degrees (* 3 sun-anomaly))) 334 (* 0.00003 (solar-sin-degrees (+ moon-anomaly sun-anomaly 335 (* -2 moon-argument)))) 336 (* 0.00003 (solar-sin-degrees 337 (+ (* 2 moon-anomaly) (* 2 moon-argument)))) 338 (* -0.00003 (solar-sin-degrees (+ moon-anomaly sun-anomaly 339 (* 2 moon-argument)))) 340 (* 0.00003 (solar-sin-degrees (- moon-anomaly sun-anomaly 341 (* -2 moon-argument)))) 342 (* -0.00002 (solar-sin-degrees (- moon-anomaly sun-anomaly 343 (* 2 moon-argument)))) 344 (* -0.00002 (solar-sin-degrees 345 (+ (* 3 moon-anomaly) sun-anomaly))) 346 (* 0.00002 (solar-sin-degrees (* 4 moon-anomaly))))) 347 (additional 348 (+ (* 0.000325 (solar-sin-degrees A1)) 349 (* 0.000165 (solar-sin-degrees A2)) 350 (* 0.000164 (solar-sin-degrees A3)) 351 (* 0.000126 (solar-sin-degrees A4)) 352 (* 0.000110 (solar-sin-degrees A5)) 353 (* 0.000062 (solar-sin-degrees A6)) 354 (* 0.000060 (solar-sin-degrees A7)) 355 (* 0.000056 (solar-sin-degrees A8)) 356 (* 0.000047 (solar-sin-degrees A9)) 357 (* 0.000042 (solar-sin-degrees A10)) 358 (* 0.000040 (solar-sin-degrees A11)) 359 (* 0.000037 (solar-sin-degrees A12)) 360 (* 0.000035 (solar-sin-degrees A13)) 361 (* 0.000023 (solar-sin-degrees A14)))) 362 (newJDE (+ JDE correction additional))) 363 (+ newJDE 364 (- (solar-ephemeris-correction 365 (extract-calendar-year 366 (calendar-gregorian-from-absolute 367 (floor (calendar-absolute-from-astro newJDE)))))) 368 (/ calendar-time-zone 60.0 24.0)))) 369 370(defun lunar-new-moon-on-or-after (d) 371 "Astronomical (Julian) day number of first new moon on or after astronomical 372\(Julian) day number d. The fractional part is the time of day. 373 374The date and time are local time, including any daylight saving rules, 375as governed by the values of calendar-daylight-savings-starts, 376calendar-daylight-savings-starts-time, calendar-daylight-savings-ends, 377calendar-daylight-savings-ends-time, calendar-daylight-time-offset, and 378calendar-time-zone." 379 (let* ((date (calendar-gregorian-from-absolute 380 (floor (calendar-absolute-from-astro d)))) 381 (year (+ (extract-calendar-year date) 382 (/ (calendar-day-number date) 365.25))) 383 (k (floor (* (- year 2000.0) 12.3685))) 384 (date (lunar-new-moon-time k))) 385 (while (< date d) 386 (setq k (1+ k)) 387 (setq date (lunar-new-moon-time k))) 388 (let* ((a-date (calendar-absolute-from-astro date)) 389 (time (* 24 (- a-date (truncate a-date)))) 390 (date (calendar-gregorian-from-absolute (truncate a-date))) 391 (adj (dst-adjust-time date time))) 392 (calendar-astro-from-absolute 393 (+ (calendar-absolute-from-gregorian (car adj)) 394 (/ (car (cdr adj)) 24.0)))))) 395 396(provide 'lunar) 397 398;;; arch-tag: 72f0b8a4-7bcc-4a1b-b67a-ff53c4a1d222 399;;; lunar.el ends here 400