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Calculate phase of the moon using Julian date

Home Page: https://jasonsturges.github.io/lunarphase-js/

License: ISC License

JavaScript 7.62% TypeScript 78.96% HTML 13.42%

astronomy npm lunar-phases moon julian emoji

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anndream danthareja probablyrory heinrichgretchen marquessbr michaelhaydendeveloper glowinthedark s9a kn666 astrological-guru thebluejester mendesbarreto mettaversesociety

lunarphase-js's Issues

CDN

Any option to use the library via CDN or as a minified JS file? (in other words: non-NPM setups)

consider adding multiple language, and next new moon/full moon? Here is my code

export function calculateMoonPhase(currentDate: Date): number {
  const newMoonDate = new Date(Date.UTC(2019, 0, 6, 1, 28, 0)); // Reference New Moon date
  const lunarCycleLength = 29.53; // Average length of the lunar cycle in days
  const diffInDays = (currentDate.getTime() - newMoonDate.getTime()) / (1000 * 3600 * 24);
  const moonPhase = (diffInDays % lunarCycleLength) / lunarCycleLength;
  return moonPhase;
}


export function estimateNextMoonPhases(currentDate: Date): { nextNewMoon: string, nextFullMoon: string} {
  const currentMoonPhase = calculateMoonPhase(currentDate);
  const lunarCycleLength = 29.53; // Average length of the lunar cycle in days

  let daysUntilNextNewMoon = lunarCycleLength * (1 - currentMoonPhase);
  if (currentMoonPhase >= 0 && currentMoonPhase < 0.5) {
      daysUntilNextNewMoon = lunarCycleLength * (0.5 - currentMoonPhase);
  }

  let daysUntilNextFullMoon = lunarCycleLength * (0.5 - currentMoonPhase);

  if (currentMoonPhase >= 0.5) {
      daysUntilNextFullMoon = lunarCycleLength * (1 - currentMoonPhase) + (lunarCycleLength / 2);
  }

  const nextNewMoon = formatMMDDDate(new Date(currentDate.getTime() + daysUntilNextNewMoon * 24 * 3600 * 1000));
  const nextFullMoon = formatMMDDDate(new Date(currentDate.getTime() + daysUntilNextFullMoon * 24 * 3600 * 1000));
  return { nextNewMoon, nextFullMoon };
}


export function getMoonPhaseName(moonPhase: number): string {
  if(moonPhase < 0.03 || moonPhase > 0.97) {
      return "NewMoon";
  } else if(moonPhase < 0.22) {
      return "WaxingCrescent";
  } else if(moonPhase < 0.28) {
      return "FirstQuarter";
  } else if(moonPhase < 0.47) {
      return "WaxingGibbous";
  } else if(moonPhase < 0.53) {
      return "FullMoon";
  } else if(moonPhase < 0.72) {
      return "WaningGibbous";
  } else if(moonPhase < 0.78) {
      return "LastQuarter";
  } else {
      return "WaningCrescent";
  }
}


export function getMoonPhasesForPeriod(currentDate: Date = new Date()): MoonPhase[] {
    const todayMoonPhaseNumber = calculateMoonPhase(currentDate);
    const todayMoonPhaseName = getMoonPhaseName(todayMoonPhaseNumber);
    const { nextNewMoon, nextFullMoon } = estimateNextMoonPhases(currentDate);
  
    const today: MoonPhase = {
      date: formatMMDDDate(currentDate),
      moonPhaseIcon: MoonPhaseIcons[todayMoonPhaseName],
      name: todayMoonPhaseName,
    };
  
    const nextNewMoonPhase: MoonPhase = {
      date: nextNewMoon,
      moonPhaseIcon: MoonPhaseIcons["NewMoon"],
      name: "NewMoon",
    };
  
    const nextFullMoonPhase: MoonPhase = {
      date: nextFullMoon,
      moonPhaseIcon: MoonPhaseIcons["FullMoon"],
      name: "FullMoon",
    };
  
    // Determine the sequence based on current phase
    let phases: MoonPhase[];
    if (todayMoonPhaseNumber < 0.5) {
      // Today -> Next Full Moon -> Next New Moon
      phases = [today, nextFullMoonPhase, nextNewMoonPhase];
    } else {
      // Today -> Next New Moon -> Next Full Moon
      phases = [today, nextNewMoonPhase, nextFullMoonPhase];
    }
  
    return phases;
}

Lunation number increases at full moon, not new moon?

Here's date vs lunation number. Why it increases at full moon?

2023-02-04: 1238
2023-02-05: 1238
2023-02-06: 1239
2023-02-07: 1239

Also, why is BLN used, it got obsolete in 1983, as wikipedia says

Considering how important this parameter is, is there any way to know which Hemisphere the user is from?
Perhaps it's out of scope for this library;
if we forward the iso country code, or the country (from react-native-localize for example), would it be possible to have a mapping function in this library to get the user's hemisphere?

Edit: I have found the following online:

window.whatHemisphere= (function(){
    var y= new Date().getFullYear();
    if(y.getTimezoneOffset()==undefined) return null;
    var jan= -(new Date(y, 0, 1, 0, 0, 0, 0).getTimezoneOffset()),
    jul= -(new Date(y, 6, 1, 0, 0, 0, 0).getTimezoneOffset()),
    diff= jan-jul;
    if(diff> 0) return 'N';
    if(diff< 0) return 'S'
    return null;
})()

do you think it could do the trick, and perhaps be part of your library?

Moon.lunarPhase() anticipating moon phase

Hi Jason! Thanks for creating this library.
I have been using it for a couple of weeks and just noticed that the method Moon.lunarPhase(date); is returning "New Moon" phase on Jan 31, 2022 at 5pm EST. However, New Moon is going to be in effect on Feb 01, 2022 at 12:46 am EST.

Lunar Day Calculation

Cool library. How about adding a lunarDay method to calculate the lunar day. Seems doable by dividing the lunar age. On the new moon it'd return 1 and so on. Returning a float would work or have lunarDay return a floored integer and accompany it with a lunarDayPercent method that returns how far into that day we are. Thoughts?

Distance as Apogee and Perigee

With distance calculation (#10), add categories of:

Apogee
Far
Average
Near
Perigee

Full moon, new moon, first quarter, and last quarter too long

This plugin is telling me the moon phases in the title last 3 to 4 days. However, these phases only happen on one moment. While waning/waxing gibbous/crescent can last multiple days, the other phases cannot.

'2021-10-20': 'full',
  '2021-10-21': 'full',
  '2021-10-22': 'full',
  '2021-10-23': 'waning-gibbous',
  '2021-10-24': 'waning-gibbous',
  '2021-10-25': 'waning-gibbous',
  '2021-10-26': 'waning-gibbous',
  '2021-10-27': 'last-quarter',
  '2021-10-28': 'last-quarter',
  '2021-10-29': 'last-quarter',
  '2021-10-30': 'last-quarter',
  '2021-10-31': 'waning-crescent',
  '2021-11-01': 'waning-crescent',
  '2021-11-02': 'waning-crescent',
  '2021-11-03': 'waning-crescent',
  '2021-11-04': 'new',
  '2021-11-05': 'new',
  '2021-11-06': 'new',
  '2021-11-07': 'waxing-crescent',
  '2021-11-08': 'waxing-crescent',
  '2021-11-09': 'waxing-crescent',
  '2021-11-10': 'waxing-crescent',
  '2021-11-11': 'first-quarter',
  '2021-11-12': 'first-quarter',
  '2021-11-13': 'first-quarter',
  '2021-11-14': 'first-quarter',
  '2021-11-15': 'waxing-gibbous',
  '2021-11-16': 'waxing-gibbous',
  '2021-11-17': 'waxing-gibbous',

UTC variant

Create UTC variants of all functions

GitHub Action workflow for npm

Add a workflow action to publish this to npm registry on release tag.

Full percent calculation

Illumination calculations

Eclipse calculations

Moon position calculations

Latitude and Longitude
Angle
Altitude of moon at sunset in degrees
Direction of moon at sunset
Direction - raising / falling

New moon time is wrong

Since the lib doesn't have a method to directly calculate new moon time, I approximated it checking lunarAgePercent:

2023-02-20T00:20:00.000Z -> 0.9999708226112602
2023-02-20T00:21:00.000Z -> 0.9999943387321082
2023-02-20T00:22:00.000Z -> 0.00001785483715366354
2023-02-20T00:23:00.000Z -> 0.00004137094219913706

So it says, that February new moon is Feb 20, 0:22UTC, but public data and pyephem library say that it will be 7:06UTC

💡 Additional use case.

@jasonsturges very cool little package and article 👏

I wonder how one might use Julian date and lunar age to arrive at the date/time when the last new moon was and when the next new moon will be.

Primary and intermediate phases

This has come up repeatedly, and need to isolate some notion of primary an intermediary phases.

Primary phases occur at a specific moment in time, and include:

New Moon
First Quarter
Full Moon
Last Quarter

Intermediate phases are ~7.4 days and do not occur at a specific moment in time. They include:

Waxing Crescent
Waxing Gibbous
Waning Gibbous
Waning Crescent

API not yet determined to implement this.

GitHub Action workflow for pages

Automate demo static site on push to main branch.

Moonrise and Moonset calculations

Determine if time zone can produce enough accuracy for calculation.

bug: NexJS build: `problem ReferenceError: exports is not defined in ES module scope`

Description

Hello @jasonsturges, I just updated the package to 2.0.2 and I am receiving this error below,

Collecting page data  ...ReferenceError: exports is not defined in ES module scope
This file is being treated as an ES module because it has a '.js' file extension and '/Users/douglasmendes/Git/xpertsea/web-insights/node_modules/lunarphase-js/package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.
    at file:///Users/douglasmendes/Git/xpertsea/web-insights/node_modules/lunarphase-js/dist/index.cjs.js:1:36
    at ModuleJob.run (node:internal/modules/esm/module_job:218:25)
    at async ModuleLoader.import (node:internal/modules/esm/loader:329:24)
    at async importModuleDynamicallyWrapper (node:internal/vm/module:430:15)

I think this change might be impacting the build for nextJS for production:

https://github.com/jasonsturges/lunarphase-js/commit/38fca43a8a09105bd3d8790a7f895510c421ac7b#diff-7ae45ad102eab3b6d7e7[…]470d7bc6507b6481575d519R19

Renaming the file from index.cjs.js to index.cjs resolved the build issue successfully locally.

Emoji for Northern and Southern hemispheres

Implement emojis for both Northern and Southern hemispheres.

trading view has different moon phases than this

On trading view https://www.tradingview.com/chart/?symbol=BITSTAMP%3ABTCUSD

they have a free indicator that you can place over charts. It shows full and new moons. Why are their phases completely different from lunarphase-js in every case? Are they wrong?

Vite upgrade

Add Lunation Number

Per discussion #1, adding Brown Lunation Number (BLN).

Lunation Number

Brown Lunation Number (BLN), per Wikipedia:

...defines lunation 1 as beginning at the first new moon of 1923, the year when Ernest William Brown's lunar theory was introduced in the American Ephemeris and Nautical Almanac.[citation needed] Lunation 1 occurred at approximately 02:41 UTC, January 17, 1923.

Moon distance from Earth calculation

DTS bundle generator

Rework Microsoft API Extractor to Vite DTS bundle generation

get future key dates

Is there a way to get the future dates for key events (full moon, half moon etc)? Right now, it seems like the caller would have to get the current position of the moon and then do calculations. If this is a common request, it might be nice to put this functional in the library.

what I'm looking for is a way to get all the full, half moon for a range of dates: ie the current month, next few months

it would be nice if the api could take a range of dates (start and end) and return the key dates

this issue might be similar to #24