added getMoon functions

CHANGELOG.md

@@ -14,3 +14,7 @@ All notable changes to this project will be documented in this file.
 
 - Moved timezone to main args and changed default behavior (major)
 - Updated test cases and readme to reflect new usage (minor)
+
+## [1.3.0] - 2013-11-13
+
+- Major updates to getMoon with own functions

getMoon.js

@@ -1,65 +1,35 @@
-const { getEarthSunDistance } = require('./getEarthSunDistance');
+const { getMoonPhase } = require('./getMoonPhase');
+const { getMoonPosition } = require('./getMoonPosition');
+const { getMoonIllumination } = require('./getMoonIllumination');
+const { getMoonVisibility } = require('./getMoonVisibility');
 
-function getMoon(date, accurate = true) {
-    const PI = Math.PI;
-    const rad = PI / 180;
-    const e = rad * 23.4397; // obliquity of the Earth
+/**
+ * Calculates detailed moon visibility information.
+ * 
+ * @param {Date} date - The date for which to calculate moon data.
+ * @param {number} [latitude=0] - Observer's latitude in decimal degrees.
+ * @param {number} [longitude=0] - Observer's longitude in decimal degrees.
+ * @param {number} [elevation=50] - Observer's elevation in meters above sea level. Default is 50 meters.
+ * @param {number} [temp=15] - Ambient temperature in degrees Celsius. Default is 15°C.
+ * @param {number} [pressure=1013.25] - Atmospheric pressure in hPa. Default is 1013.25 hPa (average sea level pressure).
+ * @param {number} [humidity=50] - Humidity in percentage. Default is 50%.
+ * @param {number} [clouds=0] - Cloudiness in percentage. Default is 0% (clear sky).
+ * @returns {Object} An object containing moon details: phase, position, illumination, and visibility.
+ */
+function getMoon(date, latitude = 0, longitude = 0, elevation = 50, temp = 15, pressure = 1013.25, humidity = 50, clouds = 0) {
+    const phase = getMoonPhase(date);
+    const position = getMoonPosition(date, latitude, longitude);
+    const illumination = getMoonIllumination(date);
 
-    function toDays(date) {
-        return (date - new Date(2000, 0, 1)) / 86400000;
-    }
-
-    function rightAscension(l, b) {
-        return Math.atan2(Math.sin(l) * Math.cos(e) - Math.tan(b) * Math.sin(e), Math.cos(l));
-    }
-
-    function declination(l, b) {
-        return Math.asin(Math.sin(b) * Math.cos(e) + Math.cos(b) * Math.sin(e) * Math.sin(l));
-    }
-
-    function sunCoords(d) {
-        const M = rad * (357.5291 + 0.98560028 * d);
-        const L = rad * (280.1470 + 360.9856235 * d) + (1.9148 - 0.004817 * d / 36525) * Math.sin(M) + 0.019993 - 0.000101 * d / 36525 * Math.cos(M);
-        return {
-            dec: declination(L, 0),
-            ra: rightAscension(L, 0)
-        };
-    }
-
-    function moonCoords(d) { 
-        const L = rad * (218.316 + 13.176396 * d);
-        const M = rad * (134.963 + 13.064993 * d);
-        const F = rad * (93.272 + 13.229350 * d);
-
-        const l = L + rad * 6.289 * Math.sin(M); // Moon's mean longitude
-        const b = rad * 5.128 * Math.sin(F);     // Moon's mean latitude
-        const dt = 385001 - 20905 * Math.cos(M); // Distance to the moon in km
-
-        return {
-            ra: rightAscension(l, b),
-            dec: declination(l, b),
-            dist: dt
-        };
-    }
-
-    const d = toDays(date);
-    const s = sunCoords(d);
-    const m = moonCoords(d);
-
-    // distance from Earth to Sun in km
-    const sdist = accurate ? getEarthSunDistance(date) : 149598000;
-
-    const phi = Math.acos(Math.sin(s.dec) * Math.sin(m.dec) + Math.cos(s.dec) * Math.cos(m.dec) * Math.cos(s.ra - m.ra));
-    const inc = Math.atan2(sdist * Math.sin(phi), m.dist - sdist * Math.cos(phi));
-    const angle = Math.atan2(Math.cos(s.dec) * Math.sin(s.ra - m.ra), Math.sin(s.dec) * Math.cos(m.dec) - Math.cos(s.dec) * Math.sin(m.dec) * Math.cos(s.ra - m.ra));
+    // Calculate visibility considering all factors
+    const visibility = getMoonVisibility(phase, position, illumination, elevation, temp, pressure, humidity, clouds);
 
     return {
-        fraction: (1 + Math.cos(inc)) / 2,
-        phase: 0.5 + 0.5 * inc * (angle < 0 ? -1 : 1) / Math.PI,
-        angle: angle
+        phase,
+        position,
+        illumination,
+        visibility
     };
 }
 
-module.exports = {
-    getMoon
-};
+module.exports = { getMoon };

getMoonIllumination.js

@@ -0,0 +1,19 @@
+// Import the SunCalc library
+const suncalc = require('suncalc');
+
+/**
+ * Calculates the moon's illumination for a given phase.
+ * @param {number} phase - The phase of the moon, from 0 (new moon) to 1 (full moon).
+ * @returns {Object} The moon's illumination details.
+ */
+function getMoonIllumination(date) {
+    const illuminationDetails = suncalc.getMoonIllumination(date);
+
+    return {
+        fraction: illuminationDetails.fraction, // Illuminated fraction of the moon; 0 = new moon, 1 = full moon
+        phase: illuminationDetails.phase,       // Moon phase (0 to 1)
+        angle: illuminationDetails.angle        // Angle in radians of the moon's bright limb
+    };
+}
+
+module.exports = { getMoonIllumination };

getMoonPhase.js

@@ -0,0 +1,23 @@
+/**
+ * Calculates the current phase of the moon as a fraction.
+ * @param {Date} date - The date for which to calculate the moon phase.
+ * @returns {number} The moon phase as a fraction from 0 (new moon) to just under 1 (end of lunar cycle).
+ */
+function getMoonPhase(date) {
+    const synodicMonth = 29.530588861; // Average length of a synodic month in days
+    // Most recent known new moon: November 13, 2023, 03:27 AM
+    const knownNewMoon = new Date(Date.UTC(2023, 10, 13, 3, 27, 0)); 
+
+    // Convert both dates to the number of milliseconds since Unix Epoch and find the difference
+    const diffInMilliseconds = date - knownNewMoon;
+
+    // Convert the difference to days
+    const diffInDays = diffInMilliseconds / 1000 / 60 / 60 / 24;
+
+    // Calculate the phase as a fraction of the synodic month
+    const phase = (diffInDays % synodicMonth) / synodicMonth;
+
+    return phase;
+}
+
+module.exports = { getMoonPhase };

getMoonPosition.js

@@ -0,0 +1,26 @@
+// Import the SunCalc library
+const suncalc = require('suncalc');
+
+/**
+ * Calculates detailed moon position information.
+ * @param {Date} date - The date and time for which to calculate the position.
+ * @param {number} latitude - Observer's latitude in decimal degrees.
+ * @param {number} longitude - Observer's longitude in decimal degrees.
+ * @returns {Object} The moon's position (azimuth, altitude), distance, and parallactic angle.
+ */
+function getMoonPosition(date, latitude, longitude) {
+    const moonPosition = suncalc.getMoonPosition(date, latitude, longitude);
+
+    // Convert azimuth and altitude from radians to degrees
+    const azimuth = moonPosition.azimuth * 180 / Math.PI;
+    const altitude = moonPosition.altitude * 180 / Math.PI;
+
+    return { 
+        azimuth, 
+        altitude,
+        distance: moonPosition.distance, // distance to moon in kilometers
+        parallacticAngle: moonPosition.parallacticAngle // parallactic angle in radians
+    };
+}
+
+module.exports = { getMoonPosition };

getMoonVisibility.js

@@ -0,0 +1,39 @@
+/**
+ * Calculates detailed moon visibility information.
+ * 
+ * @param {number} phase - The phase of the moon, from 0 (new moon) to 1 (next full moon).
+ * @param {Object} position - { azimuth, altitude, distance (km), parallacticAngle (radians) }
+ * @param {Object} illumination - { fraction, phase, angle }
+ * @param {number} [elevation=50] - Observer's elevation in meters above sea level. Default is 50 meters.
+ * @param {number} [temp=15] - Ambient temperature in degrees Celsius. Default is 15°C.
+ * @param {number} [pressure=1013.25] - Atmospheric pressure in hPa. Default is 1013.25 hPa (average sea level pressure).
+ * @param {number} [humidity=50] - Humidity in percentage. Default is 50%.
+ * @param {number} [clouds=0] - Cloudiness in percentage. Default is 0% (clear sky).
+ * @returns {Object} An object containing moon details: phase, position, illumination, and visibility.
+ */
+
+function getMoonVisibility(phase, position, illumination, elevation = 50, temp = 15, pressure = 1013.25, humidity = 50, clouds = 0) {
+    
+    /** Placeholder Simplified Algorithm...
+     * This is a very simplified algorithm that is not intended to be precise or accurate.
+     * It is loosely based on average observations from astronomy journals and other sources.
+     * Using a window of earliest general visibility until near definite visibility is reached.
+     */
+    
+    const sMonth = 29.530588861;
+    const phaseHour = 1 / 24 / sMonth; // ~ 0.001410966333
+    const startVis = phaseHour * 15;   // ~ 0.02116449584
+    const endofVis = phaseHour * 30;   // ~ 0.04232899168
+    const visWindow = endofVis - startVis;
+
+    let visibility = 0;
+    if (phase > endofVis) {
+        visibility = 1;
+    } else if (phase > startVis) {
+        visibility = (phase - startVis) / visWindow;
+    }
+
+    return visibility;
+}
+
+module.exports = { getMoonVisibility };

package-lock.json

@@ -1,21 +1,27 @@
 {
   "name": "praycalc",
-  "version": "1.2.2",
+  "version": "1.3.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "praycalc",
-      "version": "1.2.2",
+      "version": "1.3.0",
       "license": "ISC",
       "dependencies": {
-        "nrel-spa": "^1.2.2"
+        "nrel-spa": "^1.2.2",
+        "suncalc": "^1.9.0"
       }
     },
     "node_modules/nrel-spa": {
       "version": "1.2.2",
       "resolved": "https://registry.npmjs.org/nrel-spa/-/nrel-spa-1.2.2.tgz",
       "integrity": "sha512-2mycHd7PP0l+pPjPvrT6vr+PRHufCFOxsPcpaIOQ9GwhhfzgyTvSsLKPsqC6ZENNU65yq4PetT5XlWj3CoLjiQ=="
+    },
+    "node_modules/suncalc": {
+      "version": "1.9.0",
+      "resolved": "https://registry.npmjs.org/suncalc/-/suncalc-1.9.0.tgz",
+      "integrity": "sha512-vMJ8Byp1uIPoj+wb9c1AdK4jpkSKVAywgHX0lqY7zt6+EWRRC3Z+0Ucfjy/0yxTVO1hwwchZe4uoFNqrIC24+A=="
     }
   }
 }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "praycalc",
-  "version": "1.2.3",
+  "version": "1.3.0",
   "description": "Prayer times calculator using nrel-spa and custom formula for Fajr and Isha angles (as well as traditional static angle methods in the All function)",
   "main": "index.js",
   "scripts": {
@@ -13,6 +13,7 @@
   "author": "USF",
   "license": "ISC",
   "dependencies": {
-    "nrel-spa": "^1.2.2"
+    "nrel-spa": "^1.2.2",
+    "suncalc": "^1.9.0"
   }
 }

test-moon.js

@@ -0,0 +1,21 @@
+const { getMoon } = require('./index');
+
+const date = new Date();
+
+/* NYC - minimum params
+const city = "New York"
+const lat = 40.7128;
+const lng = -74.006;
+*/
+
+// Jakarta - all params
+const city = "Jakarta"
+const lat = -6.2088
+const lng = 106.8456
+
+// Get results
+const get = getMoon(date, lat, lng);
+
+// Print results
+console.log(`\nTest: ${city} with current Date():\n`)
+console.log("getMoon =", get, "\n");