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