moon-cycle

Maps any JavaScript Date to the correct NASA moon phase image filename. Two algorithms: synodic-cycle mapping (708 images) and calendar-year mapping (8,760 images).

Not published to npm. The image dataset (~438 MB of hourly WebP photos from NASA's Scientific Visualization Studio) lives in this repository. Use CDN or clone.

Install

# Clone to get code and images together
git clone https://github.com/acamarata/moon-cycle.git

# Or add the code-only package via git
pnpm add github:acamarata/moon-cycle

Quick Start

import { cycleMonth, cdnUrl } from 'moon-cycle';

const filename = cycleMonth();                     // e.g. "354.webp"
const url = cdnUrl(filename, 'mm', 256, 75);
// => 'https://cdn.jsdelivr.net/gh/acamarata/moon-cycle@main/mm-256-75/354.webp'

CommonJS:

const { cycleMonth, cdnUrl } = require('moon-cycle');

Documentation

Full reference: GitHub Wiki

• API Reference
• Architecture
• Examples

Related

• nrel-spa: Pure JS NREL Solar Position Algorithm
• pray-calc: Islamic prayer times
• moon-sighting: Lunar crescent visibility

Acknowledgments

Moon phase imagery from NASA's Scientific Visualization Studio:

Ernie Wright (2023). Moon Phase and Libration, 2023 [Data set]. NASA Scientific Visualization Studio. https://svs.gsfc.nasa.gov/5187

Images are in the public domain per NASA's media usage guidelines.

License

MIT. See LICENSE for the full text.