tsukiMOJi

Moon phase emoji for any date. 月 (tsuki, "moon") + moji, as in emoji.

const { getMoonPhase, emoji } = require("tsukimoji");
// or: import { getMoonPhase, emoji } from "tsukimoji";

const phase = getMoonPhase();
phase.emoji;        // "🌔"
phase.name;         // "Waxing Gibbous"
phase.ageDays;      // 12.3
phase.illumination; // 0.87

emoji();            // just the emoji, for "now"
getMoonPhase(new Date("2026-01-01")); // phase for any specific date

// Moon faces: 🌚 for New Moon and 🌝 for Full Moon
emoji(new Date("2026-10-26T04:00:00Z"), { faces: true }); // "🌝"

Phase calendar

const { calendar, calendarCSV, calendarJSON, calendarText } = require("tsukimoji");

calendar("2026-10");                  // one entry per day of October 2026
calendarCSV("2026-11", "2027-02");    // November through February, as CSV
calendarJSON(2026);                   // the whole year, as JSON
calendarText("2026", "2027");         // two years of month grids, as text

Pass a year ("2026" or 2026), a month ("2026-10"), a day ("2026-10-04") or a Date, plus an optional second one to make a range. Each new moon, quarter and full moon appears on the day it happens, with the exact time. See the main README for the formats.

Installation

npm install tsukimoji

How it works

tsukiMOJi measures elapsed time since a known new moon (2000-01-06 18:14 UTC) against the synodic month (29.530588853 days) to find how far into the current lunar cycle a given moment falls, then maps that fraction onto the eight standard moon-phase emoji (🌑🌒🌓🌔🌕🌖🌗🌘). Illumination is derived separately from the same cycle position via a cosine curve, for display purposes.

License

MIT