Merge pull request #71 from WimDeMeester/master

Added the moon phase ratio of the moon.

Author: WimDeMeester

changelog.md

@@ -6,7 +6,7 @@ All notable changes to `laravel-astronomy-library` will be documented in this fi
 
 ### Added
 
-- Added the moon phase ratio to the calculation of the illumination of the moon.
+- Added the moon phase ratio of the moon.
 
 ## Version 5.4
 

readme.md

@@ -525,6 +525,9 @@ $moon->calculateEquatorialCoordinates($date, $geo_coords, $heightOfLocation);
 
 // Calculate the illumination of the moon
 $moon->illuminatedFraction($date);
+
+// Calculate the moon phase ration (0-1) of the moon
+$moon->getPhaseRatio($date);
 ```
 
 ## Change log

src/deepskylog/AstronomyLibrary/Targets/Moon.php

@@ -365,15 +365,15 @@ private function _calculateEquatorialCoordinates(Carbon $date, GeographicalCoord
     }
 
     /**
-     * Calculates the illuminated fraction of the planet.
+     * Calculates the illuminated fraction of the moon.
      *
      * @param Carbon $date The date for which to calculate the fraction
      *
-     * @return array The illuminated fraction, the phase ratio
+     * @return float The illuminated fraction, the phase ratio
      *
      * See chapter 58 of Astronomical Algorithms
      */
-    public function illuminatedFraction(Carbon $date): array
+    public function illuminatedFraction(Carbon $date): float
     {
         // T = julian centuries since epoch J2000.0
         $T = (Time::getJd($date) - 2451545.0) / 36525.0;
@@ -396,6 +396,41 @@ public function illuminatedFraction(Carbon $date): array
 
         $i = $i - floor($i / 360.0) * 360.0;
 
-        return [round((1 + cos(deg2rad($i))) / 2, 3), $i / 360];
+        return round((1 + cos(deg2rad($i))) / 2, 3);
+    }
+
+    /**
+     * Calculates the phase ration of the moon (0 - 1).
+     *
+     * @param Carbon $date The date for which to calculate the phase ration
+     *
+     * @return float The phase ratio
+     *
+     * See chapter 58 of Astronomical Algorithms
+     */
+    public function getPhaseRatio(Carbon $date): float
+    {
+        // T = julian centuries since epoch J2000.0
+        $T = (Time::getJd($date) - 2451545.0) / 36525.0;
+
+        // Mean elongation of the moon
+        $D = (new Coordinate(297.8501921 + 445267.1114023 * $T - 0.0018819 * $T ** 2 + $T ** 3 / 545868.0 - $T ** 4 / 113065000.0))->getCoordinate();
+
+        // Sun's mean anomaly
+        $M = (new Coordinate(357.5291092 + 35999.0502909 * $T - 0.0001536 * $T ** 2 + $T ** 3 / 24490000.0))->getCoordinate();
+
+        // Moon's mean anomaly
+        $M_accent = (new Coordinate(134.9633964 + 477198.8675055 * $T + 0.0087414 * $T ** 2 + $T ** 3 / 69699.0 - $T ** 4 / 14712000.0))->getCoordinate();
+
+        $i = 180 - $D - 6.289 * sin(deg2rad($M_accent))
+                                     + 2.100 * sin(deg2rad($M))
+                                     - 1.274 * sin(deg2rad(2 * $D - $M_accent))
+                                     - 0.658 * sin(deg2rad(2 * $D))
+                                     - 0.214 * sin(deg2rad(2 * $M_accent))
+                                     - 0.110 * sin(deg2rad($D));
+
+        $i = $i - floor($i / 360.0) * 360.0;
+
+        return $i / 360;
     }
 }

tests/Unit/TargetTest.php

@@ -958,7 +958,7 @@ public function testMoonIllumination()
     {
         $date = Carbon::create(1992, 4, 12, 0, 0, 0, 'UTC');
         $moon = new Moon();
-        $illum = $moon->illuminatedFraction($date)[0];
+        $illum = $moon->illuminatedFraction($date);
 
         $this->assertEqualsWithDelta(0.680, $illum, 0.001);
     }