Swiss Ephemeris Server

A Model Context Protocol (MCP) server that provides astronomical calculations using the Swiss Ephemeris library. Calculate planetary positions, houses, chart points, and asteroids for any date and location.

Features

• Planetary Positions: Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto
• Lunar Nodes: True and Mean Node calculations
• Asteroids: Chiron, Ceres, Pallas, Juno, Vesta, Lilith
• Houses: 12-house system using Placidus
• Chart Points: Ascendant, Midheaven, IC, Descendant
• Additional Points: South Node, Part of Fortune

Installation

Prerequisites for Local Development

For local use with Claude Desktop, you need to install the Swiss Ephemeris swetest command:

# Install swetest (required for Claude Desktop usage)
git clone https://github.com/aloistr/swisseph.git /tmp/swisseph && \
    cd /tmp/swisseph && \
    make && \
    cp swetest /usr/local/bin/ && \
    rm -rf /tmp/swisseph

Claude Desktop

Add to your Claude Desktop configuration:

{
  "mcpServers": {
    "swissEphemeris": {
      "command": "npx",
      "args": ["github:dm0lz/swiss-ephemeris-mcp-server"]
    }
  }
}

Manual Installation

git clone https://github.com/dm0lz/swiss-ephemeris-mcp-server.git
cd swiss-ephemeris-mcp-server
npm install
npm start

Usage

The server provides four main tools:

calculate_planetary_positions

Calculate astronomical data for a specific date, time, and location.

Parameters:

• datetime (string): ISO8601 format, e.g., "1985-04-12T23:20:50Z"
• latitude (number): Latitude in decimal degrees (-90 to 90)
• longitude (number): Longitude in decimal degrees (-180 to 180)

Returns:

• planets: Positions of all planets and celestial bodies
• houses: 12 astrological houses
• chart_points: Ascendant, Midheaven, IC, Descendant
• additional_points: South Node, Part of Fortune

calculate_transits

Calculate birth chart positions and current transits for comparison.

Parameters:

• birth_datetime (string): Birth datetime in ISO8601 format
• latitude (number): Birth latitude in decimal degrees
• longitude (number): Birth longitude in decimal degrees

Returns:

• natal_chart: Complete birth chart data
• current_transits: Current planetary positions
• calculation_time: Timestamp of transit calculation

calculate_solar_revolution

Calculate solar return chart for a specific year (when Sun returns to natal position).

Parameters:

• birth_datetime (string): Birth datetime in ISO8601 format
• birth_latitude (number): Birth latitude in decimal degrees
• birth_longitude (number): Birth longitude in decimal degrees
• return_year (number): Year for solar return calculation (e.g., 2024)
• return_latitude (number, optional): Solar return location latitude
• return_longitude (number, optional): Solar return location longitude

Returns:

• natal_chart: Original birth chart data
• solar_return_chart: Solar return chart for the specified year
• natal_sun_longitude: Original Sun position in degrees
• return_sun_longitude: Solar return Sun position in degrees
• calculation_time: Timestamp of calculation

calculate_synastry

Calculate synastry chart between two people for relationship compatibility analysis.

Parameters:

• person1_datetime (string): Person 1 birth datetime in ISO8601 format
• person1_latitude (number): Person 1 birth latitude in decimal degrees
• person1_longitude (number): Person 1 birth longitude in decimal degrees
• person2_datetime (string): Person 2 birth datetime in ISO8601 format
• person2_latitude (number): Person 2 birth latitude in decimal degrees
• person2_longitude (number): Person 2 birth longitude in decimal degrees

Returns:

• person1_chart: Complete birth chart for person 1
• person2_chart: Complete birth chart for person 2
• synastry_aspects: Array of planetary aspects between the charts
• calculation_time: Timestamp of calculation

Docker

# Build and run
docker build -t swiss-ephemeris-mcp .
docker run -p 8000:8000 -e MCP_HTTP_MODE=true swiss-ephemeris-mcp

# Health check
curl http://localhost:8000/health

Transport Modes

• Stdio: Default mode for Claude Desktop integration
• HTTP: Use MCP_HTTP_MODE=true for web integration via ngrok

Links

• MCP URL: https://www.theme-astral.me/mcp
• Repository: https://github.com/dm0lz/swiss-ephemeris-mcp-server
• Swiss Ephemeris: https://www.astro.com/swisseph/

License

MIT