Calculate the moon phase.
This is an approximate calculation.
$ npm i celestial-moon
const moon = require('celestial-moon');
const phase = moon.calculate(2020, 11, 10, 9, 30, 0, 0);
console.log(phase.age); //since last new moon
console.log(phase.name); //'waning-crescent'
Please feel free to contribute by creating a Pull Request including test code.