211 lines
8.5 KiB
PHP
211 lines
8.5 KiB
PHP
<?php
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/**
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* @brief lunarPhase, a plugin for Dotclear 2
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*
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* @package Dotclear
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* @subpackage Plugin
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*
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* @author Tomtom, Pierre Van Glabeke and Contributors
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*
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* @copyright Jean-Crhistian Denis
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* @copyright GPL-2.0 https://www.gnu.org/licenses/gpl-2.0.html
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*/
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if (!defined('DC_RC_PATH')) {
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return null;
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}
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class lunarPhase
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{
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# Astronomical constants.
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public const epoch = 2444238.5; # 1980 January 0.0
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# Constants defining the Sun's apparent orbit.
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public const elonge = 278.833540; # ecliptic longitude of the Sun at epoch 1980.0
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public const elongp = 282.596403; # ecliptic longitude of the Sun at perigee
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public const eccent = 0.016718; # eccentricity of Earth's orbit
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public const sunsMax = 1.495985e8; # semi-major axis of Earth's orbit, km
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public const sunAngSiz = 0.533128; # sun's angular size, degrees, at semi-major axis distance
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# Elements of the Moon's orbit, epoch 1980.0.
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public const mmLong = 64.975464; # moon's mean longitude at the epoch
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public const mmLongp = 349.383063; # mean longitude of the perigee at the epoch
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public const mlNode = 151.950429; # mean longitude of the node at the epoch
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public const mInc = 5.145396; # inclination of the Moon's orbit
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public const mEcc = 0.054900; # eccentricity of the Moon's orbit
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public const mAngSiz = 0.5181; # moon's angular size at distance a from Earth
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public const msMax = 384401.0; # semi-major axis of Moon's orbit in km
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public const mParallax = 0.9507; # parallax at distance a from Earth
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public const synodic = 29.53058868; # synodic month (new Moon to new Moon)
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protected $live;
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protected $previsions;
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public function __construct()
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{
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$this->live = new ArrayObject();
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$this->previsions = new ArrayObject();
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$this->setLive();
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$this->setPrevisions();
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}
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public function getLive()
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{
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return $this->live;
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}
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public function getPrevisions()
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{
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return $this->previsions;
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}
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private function setLive()
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{
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$day = $this->jTime(time()) - self::epoch;
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# Calculate sun's position and angle
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$N = $this->fixAngle((360 / 365.2422) * $day);
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$M = $this->fixAngle($N + self::elonge - self::elongp);
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$Ec = $this->kepler($M, self::eccent);
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$Ec = sqrt((1 + self::eccent) / (1 - self::eccent)) * tan($Ec / 2);
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$Ec = 2 * $this->toDeg(atan($Ec));
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$lambdaSun = $this->fixAngle($Ec + self::elongp);
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$F = ((1 + self::eccent * cos($this->toRad($Ec))) / (1 - self::eccent * self::eccent));
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# Calculate moon's age, position and angle
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$ml = $this->fixAngle(13.1763966 * $day + self::mmLong);
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$MM = $this->fixAngle($ml - 0.1114041 * $day - self::mmLongp);
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$MN = $this->fixAngle(self::mlNode - 0.0529539 * $day);
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$Ev = 1.2739 * sin($this->toRad(2 * ($ml - $lambdaSun) - $MM));
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$Ae = 0.1858 * sin($this->toRad($M));
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$A3 = 0.37 * sin($this->toRad($M));
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$MmP = $MM + $Ev - $Ae - $A3;
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$mEc = 6.2886 * sin($this->toRad($MmP));
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$A4 = 0.214 * sin($this->toRad(2 * $MmP));
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$lP = $ml + $Ev + $mEc - $Ae + $A4;
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$V = 0.6583 * sin($this->toRad(2 * ($lP - $lambdaSun)));
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$lPP = $lP + $V;
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$NP = $MN - 0.16 * sin($this->toRad($M));
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$y = sin($this->toRad($lPP - $NP)) * cos($this->toRad(self::mInc));
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$x = cos($this->toRad($lPP - $NP));
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$lambdaMoon = $this->toDeg(atan2($y, $x));
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$lambdaMoon += $NP;
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$mage = $lPP - $lambdaSun;
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$BetaM = $this->toDeg(asin(sin($this->toRad($lPP - $NP)) * sin($this->toRad(self::mInc))));
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$this->live['illumination'] = (1 - cos($this->toRad($mage))) / 2;
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$this->live['age'] = self::synodic * ($this->fixAngle($mage) / 360.0);
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$this->live['dist_to_earth'] = (self::msMax * (1 - self::mEcc * self::mEcc)) / (1 + self::mEcc * cos($this->toRad($MmP + $mEc)));
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$this->live['dist_to_sun'] = self::sunsMax / $F;
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$this->live['sun_angle'] = $F * self::sunAngSiz;
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$this->live['moon_angle'] = self::mAngSiz / ($this->live['dist_to_earth'] / self::msMax);
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$this->live['parallax'] = self::mParallax / ($this->live['dist_to_earth'] / self::msMax);
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$this->setPhase();
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}
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private function setPhase()
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{
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if ($this->live['age'] >= self::synodic || $this->live['age'] <= self::synodic / 8) {
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$this->live['id'] = 'new_moon';
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$this->live['name'] = __('New moon');
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} elseif ($this->live['age'] >= self::synodic / 8 && $this->live['age'] <= self::synodic / 4) {
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$this->live['id'] = 'waxing_crescent_moon';
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$this->live['name'] = __('Waxing crescent moon');
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} elseif ($this->live['age'] >= self::synodic / 4 && $this->live['age'] <= self::synodic * 3 / 8) {
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$this->live['id'] = 'first_quarter_moon';
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$this->live['name'] = __('First quarter moon');
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} elseif ($this->live['age'] >= self::synodic * 3 / 8 && $this->live['age'] <= self::synodic / 2) {
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$this->live['id'] = 'waxing_gibbous_moon';
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$this->live['name'] = __('Waxing gibbous moon');
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} elseif ($this->live['age'] >= self::synodic / 2 && $this->live['age'] <= self::synodic * 5 / 8) {
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$this->live['id'] = 'full_moon';
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$this->live['name'] = __('Full moon');
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} elseif ($this->live['age'] >= self::synodic * 5 / 8 && $this->live['age'] <= self::synodic * 3 / 4) {
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$this->live['id'] = 'waning_gibbous_moon';
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$this->live['name'] = __('Waning gibbous moon');
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} elseif ($this->live['age'] >= self::synodic * 3 / 4 && $this->live['age'] <= self::synodic * 7 / 8) {
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$this->live['id'] = 'last_quarter_moon';
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$this->live['name'] = __('Last quarter moon');
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} elseif ($this->live['age'] >= self::synodic * 7 / 8 && $this->live['age'] <= self::synodic) {
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$this->live['id'] = 'waning_crescent_moon';
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$this->live['name'] = __('Waning crescent moon');
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}
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}
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private function setPrevisions()
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{
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$ts_day = 24 * 60 * 60;
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$ts_synodic = self::synodic * $ts_day;
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$start = time() - $this->live['age'] * $ts_day;
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$this->previsions['waxing_crescent_moon'] = [
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'name' => __('Waxing crescent moon'),
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'date' => $start + $ts_synodic / 8,
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];
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$this->previsions['first_quarter_moon'] = [
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'name' => __('First quarter moon'),
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'date' => $start + $ts_synodic / 4,
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];
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$this->previsions['waxing_gibbous_moon'] = [
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'name' => __('Waxing gibbous moon'),
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'date' => $start + $ts_synodic * 3 / 8,
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];
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$this->previsions['full_moon'] = [
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'name' => __('Full moon'),
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'date' => $start + $ts_synodic / 2,
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];
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$this->previsions['waning_gibbous_moon'] = [
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'name' => __('Waning gibbous moon'),
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'date' => $start + $ts_synodic * 5 / 8,
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];
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$this->previsions['last_quarter_moon'] = [
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'name' => __('Last quarter moon'),
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'date' => $start + $ts_synodic * 3 / 4,
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];
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$this->previsions['waning_crescent_moon'] = [
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'name' => __('Waning crescent moon'),
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'date' => $start + $ts_synodic * 7 / 8,
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];
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$this->previsions['new_moon'] = [
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'name' => __('New moon'),
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'date' => $start + $ts_synodic,
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];
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}
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private function fixAngle($x)
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{
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return ($x - 360.0 * (floor($x / 360.0)));
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}
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private function toRad($x)
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{
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return ($x * (M_PI / 180.0));
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}
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private function toDeg($x)
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{
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return ($x * (180.0 / M_PI));
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}
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private function jTime($t)
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{
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return ($t / 86400) + 2440587.5;
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}
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private function kepler($m, $ecc)
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{
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$delta = null;
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$EPSILON = 1e-6;
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$m = $this->toRad($m);
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$e = $m;
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while (abs((int) $delta) > $EPSILON) {
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$delta = $e - $ecc * sin($e) - $m;
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$e -= $delta / (1 - $ecc * cos($e));
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}
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return ($e);
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}
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}
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