# Skyfold Printable Moon Calendar

> A printable Moon calendar for any month or year: phases, moonrise, moonset, perigee and supermoons. Draws the Moon of every day of a month or year for your place, with the illuminated fraction, moonrise and moonset in local time, the four principal phases, perigee and apogee with distances and the supermoons, as a print-ready PDF, SVG and PNG in 17 languages.

Part of usefulweb.site (https://usefulweb.site/). Part of [Skyfold](https://skyfold.usefulweb.site/) (ownerApp: skyfold). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://skyfoldmooncalendar.usefulweb.site/ (interactive tool at https://skyfoldmooncalendar.usefulweb.site/tool)
- JSON API: POST https://skyfoldmooncalendar.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://skyfoldmooncalendar.usefulweb.site/api/v1/tool)
- OpenAPI: https://skyfoldmooncalendar.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://skyfoldmooncalendar.usefulweb.site/mcp - tool `skyfold_moon_calendar`

## Inputs
- location (text): Location (latitude, longitude) - Decimal degrees such as 52.09, 5.12 (north and east positive), or DMS, UTM, MGRS, Maidenhead or a plus code.
- elevation (number): Elevation above sea level
- timeZone (text): Time zone - IANA name such as Europe/Berlin or America/New_York, or a fixed offset such as UTC+2.
- year (integer): Year
- month (select): Month
- layout (select): Layout
- lang (select): Language of the calendar
- paper (select): Paper size
- orientation (select): Orientation
- weekStart (select): Week starts on
- placeLabel (text): Place line

## Method
- Phase and illuminated fraction at local noon of each day from the Skyfold ephemeris (truncated ELP-2000/82 Moon, VSOP87 Sun); principal phases where the Moon–Sun elongation is 0°, 90°, 180° and 270°.
- Moonrise and moonset: upper limb on an ideal horizon with 34′ of refraction, topocentric (U.S. Naval Observatory convention).
- Perigee and apogee: extrema of the geocentric centre distance; 2026 values agree with published tables within 3 minutes and 15 km. Supermoon after R. Nolle: a full or new Moon within 10 % of the perigee end of that orbit’s distance range.
- Layout, fonts and the PDF/SVG/PNG writers are Printshop’s (Noto fonts, Intl month and weekday names, right-to-left order for Arabic).

## Limits
- Moonrise and moonset assume a flat horizon at sea level; hills and buildings delay rising and advance setting. The phase drawing shows the Moon as seen from the northern hemisphere, mirrored for southern places.