# Skyfold Planet Conjunctions and Best Evenings

> Close pairings of the Moon and planets and their best evenings for the next months, as a calendar. Finds every close approach of the Moon, Mercury, Venus, Mars, Jupiter and Saturn, the oppositions of Mars to Neptune and the greatest elongations of Mercury and Venus, checks whether you can see them in the evening or morning twilight at your place and exports them as an .ics calendar.

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://skyfoldconjunctions.usefulweb.site/ (interactive tool at https://skyfoldconjunctions.usefulweb.site/tool)
- JSON API: POST https://skyfoldconjunctions.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://skyfoldconjunctions.usefulweb.site/api/v1/tool)
- OpenAPI: https://skyfoldconjunctions.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://skyfoldconjunctions.usefulweb.site/mcp - tool `skyfold_conjunctions`

## 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.
- startDate (date): From
- months (integer): Months
- planetLimit (number): Closest planet pairs within
- moonLimit (number): Moon and planet within
- includeMoon (boolean): Include the Moon
- visibleOnly (boolean): Only events visible from this place

## Method
- Apparent geocentric positions from the Skyfold ephemeris (VSOP87 planets with light time and aberration, ELP-2000/82 Moon); separations sampled every 12 hours (Moon pairs every 2 hours) and refined to the minute by golden-section search.
- Oppositions: the planet’s ecliptic longitude differs from the Sun’s by 180°; greatest elongations: maxima of the Sun–planet angle for Mercury and Venus, east = evening sky.
- Visible: at evening or morning civil twilight (Sun 6° down) the lower of the two objects stands at least 5° above the horizon and both are at least 12° from the Sun; the visible twilight closest to the event is suggested (with the separation at that moment), oppositions at the planet’s transit.
- The 2026 results reproduce the published dates (Venus–Saturn 8 March, Venus–Jupiter 9 June 1.6°, Mercury–Jupiter 15 August, oppositions of Jupiter 10 January and Saturn 4 October).

## Limits
- Separations are geocentric; seen from your place the Moon shifts by up to 1° (parallax), so Moon pairings can look closer or wider, and close ones can become occultations for some regions.