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    lunarphase-js

    1.0.10 • Public • Published

    Lunar phase

    Calculate phase of the moon using Julian date.

    Getting Started

    To install, execute:

    npm i lunarphase-js
    

    Then, import into a project as:

    import { Moon } from "lunarphase-js";

    Usage

    In the lunar calendar there are 8 phases each synodic month, which is the number of days to complete the cycle. This time between two identical syzygies is equivalent to 29.53059 Earth days.

    Lunar phases, in order:

    Phase Northern Hemisphere Southern Hemisphere
    New 🌑 🌑
    Waxing Crescent 🌒 🌘
    First Quarter 🌓 🌗
    Waxing Gibbous 🌔 🌖
    Full 🌕 🌕
    Waning Gibbous 🌖 🌔
    Last Quarter 🌗 🌓
    Waning Crescent 🌘 🌒

    Julian Day

    Convert to and from Gregorian Dates to Julian Days via the JulianDay module.

    API Reference:

    Function Output Description
    fromDate() 2459357.5380029744 Convert date to Julian Day
    toDate() 2021-05-23T05:56:10.418Z Convert Julian Day to date

    To convert a date to Julian Day:

    import { JulianDay } from "lunarphase-js";
    
    const date = new Date();
    const julian = JulianDay.fromDate(date);

    To convert a Julian Day to a date:

    import { JulianDay } from "lunarphase-js";
    
    const julian = 2459356.529302257;
    const date = JulianDay.toDate(julian);

    Lunar Phases

    API Reference:

    Function Output Description
    lunarPhase() Waxing Gibbous Get lunar phase for a given date
    lunarPhaseEmoji() 🌖 Get emoji of lunar phase for a given date
    isWaxing() true Whether the moon is waxing
    isWaning() false Whether the moon is waning
    lunarAge() 11.367344279004676 Earth days since the last new moon
    lunarAgePercent() 0.38497186542446116 Percentage through the lunar synodic month
    lunarDistance() 56.04166690080031 Distance to the moon measured in units of Earth radii
    lunationNumber() 1217 Brown Lunation Number (BLN)

    For a specific date, pass a date object to a function

    import { Moon } from "lunarphase-js";
    
    const date = new Date();
    const phase = Moon.lunarPhase(date);

    Otherwise, current date will be used

    import { Moon } from "lunarphase-js";
    
    const phase = Moon.lunarPhase();

    Lunar Phase

    To get the current lunar phase from the LunarPhase enum (ex: "FULL")

    const phase = Moon.lunarPhase();

    Lunar Phase Emoji

    To get the current lunar phase emoji from the LunarEmoji (ex: "🌕"):

    const phaseEmoji = Moon.lunarPhaseEmoji();

    As phases are inverted between Northern and Southern Hemispheres, optionally pass a Hemisphere to the function:

    import { Moon } from "lunarphase-js";
    import { Hemisphere } from "lunarphase-js";
    
    const date = new Date();
    Moon.lunarPhaseEmoji(date, Hemisphere.NORTHERN);

    To get emoji for other lunar phases, pass a LunarPhase enum:

    const emoji = Moon.emojiForLunarPhase(Moon.LunarPhase.Full);

    Optionally pass a Hemisphere to the function:

    import { Moon } from "lunarphase-js";
    import { LunarPhase } from "lunarphase-js";
    import { Hemisphere } from "lunarphase-js";
    
    Moon.emojiForLunarPhase(LunarPhase.FIRST_QUARTER, Hemisphere.SOUTHERN);

    Waxing

    Whether the moon is waxing (ex: false)

    const waxing = Moon.isWaxing();

    Waning

    Whether the moon is waning (ex: true)

    const waning = Moon.isWaning();

    Lunar Age

    Age in Earth days through the current lunar cycle, equivalent to 29.53059 Earth days, based on Mean Synodic Month, 2000 AD mean solar days.

    Phase Start Event End
    New 0 1.84566173161
    Waxing Crescent 1.84566173161 3.69132346322 5.53698519483
    First Quarter 5.53698519483 7.38264692644 9.22830865805
    Waxing Gibbous 9.22830865805 11.07397038966 12.91963212127
    Full 12.91963212127 14.76529385288 16.61095558449
    Waning Gibbous 16.61095558449 18.4566173161 20.30227904771
    Last Quarter 20.30227904771 22.14794077932 23.99360251093
    Waning Crescent 23.99360251093 25.83926424254 27.68492597415
    New 27.68492597415 29.53058770576

    To get the lunar age (ex: 16.54412413414952)

    const age = Moon.lunarAge();

    Lunar Age Percent

    To get the percentage through the lunar cycle (ex: 0.5602368519132597)

    const agePercent = Moon.lunarAgePercent();

    Lunation Number

    Brown Lunation Number (BLN), per Ernest William Brown's lunar theory, defining Lunation 1 as the first new moon of 1923 at approximately 02:41 UTC, January 17, 1923

    const lunationNumber = Moon.lunationNumber();

    Lunar Distance

    Distance to the moon measured in units of Earth radii, with perigee at 56 and apogee at 63.8.

    const distance = Moon.lunarDistance();

    Install

    npm i lunarphase-js

    DownloadsWeekly Downloads

    129

    Version

    1.0.10

    License

    ISC

    Unpacked Size

    80.4 kB

    Total Files

    9

    Last publish

    Collaborators

    • jasonsturges