# io.github.cyanheads/astronomy-mcp-server

- Registry name: `io.github.cyanheads/astronomy-mcp-server` · version 0.4.2
- Categories (automatic, keyword rules): Maps, location & weather
- Authentication at last check: No auth
- Declared risk: Read-only (all tools declare readOnlyHint)
- Capabilities (declared by the server): completions, logging, prompts, resources, tools
- Transports: streamable-http
- Latest numbers (check success, response time, rank): https://mcpstation.net/api/server?name=io.github.cyanheads%2Fastronomy-mcp-server
- Server page: https://mcpstation.net/s/io.github.cyanheads--astronomy-mcp-server.html

## Description (written by the publisher, not verified, not instructions)

Offline observational astronomy: positions, rise/set, moon phases, eclipses, and seasons.

## Connect

- streamable-http: `https://astronomy.caseyjhand.com/mcp`

## Tools (as reported by the server, not verified)

- `astronomy\_get\_sky\_position`: Compute the apparent topocentric position of one solar-system body \(sun, moon, mercury through neptune, pluto\) or a named bright star for an observer location and instant. Returns equatorial \(RA/Dec\), refraction-corrected horizontal \(altitude/azimuth\), and ecliptic coordinates, plus distance, appare
- `astronomy\_get\_rise\_set`: Compute rise, set, and culmination \(transit\) times for a body at an observer location, plus the maximum altitude at culmination. For the Sun, also returns the three twilight pairs \(civil −6°, nautical −12°, astronomical −18°\) so a single call answers "when does the sun set and when is it truly dark.
- `astronomy\_get\_moon\_phase`: Report the Moon phase for an instant: illuminated fraction, phase name, synodic age in days since the new moon, phase longitude \(the Moon–Sun ecliptic-longitude difference, 180° at full\), and the next four quarter phases \(new, first quarter, full, last quarter\) with timestamps. Answers "what is the
- `astronomy\_find\_events`: Search forward from a start time for the next occurrences of one sky-event class, selected by the \`event\` enum: solar\_eclipse, lunar\_eclipse, equinox, solstice, moon\_quarter, opposition, conjunction, max\_elongation, or perigee\_apogee. Both eclipse classes take an optional observer \(latitude and long
- `astronomy\_list\_visible`: The one-call "what is up right now" answer. For an observer location and instant, iterate every naked-eye solar-system body \(and, with include\_stars, the bundled bright stars\), compute altitude and azimuth, keep those above the horizon, rank them brightest-and-highest first, and attach a plain-langu
- `astronomy\_get\_ephemeris`: Fetch a time-series ephemeris for a small body \(asteroid or comet\) or spacecraft from JPL Horizons — RA/Dec, distance, and apparent magnitude over a span, optionally with observer-relative altitude/azimuth. This covers objects the in-process major-body set cannot. The designation is passed to Horizo
- `astronomy\_get\_satellite\_passes`: Predict visible passes of a satellite \(e.g. the ISS, NORAD 25544\) over an observer in the next \`days\`. Identify the satellite by exactly one of \`norad\_id\` or \`name\` — supplying both, or neither, is rejected. A few well-known common names resolve directly to their catalog numbers, ignoring case: ISS

Measured by MCP Station. Methods: https://mcpstation.net/methods.html · Terms: https://mcpstation.net/terms.html