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Open Ephemeris MCP server

Lets your AI calculate real astrology charts, transits, and Human Design from NASA data.

This is a helper that connects your AI to OpenEphemeris, a service that does real astrology math using NASA's planetary data. Instead of your AI guessing where Mars was on your birthday, it looks it up properly. It is handy for anyone who likes astrology, Human Design, Vedic charts, or Chinese BaZi and wants answers they can trust.

What is an MCP server? The 30-second version

On its own, your AI can only chat and make things up. An MCP server is a small helper program that gives your AI a new skill or a connection to an app or service. This one connects your AI to OpenEphemeris, so when you ask about a chart or a transit, your AI can actually look it up instead of guessing. You just talk normally, and the helper does the calculating behind the scenes.

What this MCP server does

You ask your AI something like 'calculate my natal chart' and give it your birth date, time, and place. Your AI sends that to this helper, which talks to OpenEphemeris and does the real astronomy math. OpenEphemeris sends back the placements, dates, and degrees, and your AI shows them to you in the chat. If you are in Claude or ChatGPT, some answers open as a clickable chart you can explore. No numbers are invented, they come from the same NASA data used for 1,100 years of sky positions.

Flow diagram: you ask your AI “Calculate my natal chart from my birth details”, the Open Ephemeris MCP server connects it to Open Ephemeris, and you get back your chart, in the chat.

Click to zoom

What you can do with it

Calculate a natal chart from a birth date, time, and place
Find upcoming transits to your chart over the next months
Check the current moon phase and void-of-course status
Look up the next solar eclipse visible from a city
Generate a Human Design bodygraph from birth data
Calculate a Vedic (sidereal) chart or a Chinese BaZi chart
Compare two people's charts with a synastry or composite chart

Try asking your AI

“Calculate a natal chart for someone born April 15, 1990 at 2:30 PM in Chicago.”
“Find all Saturn transits to my natal Sun in the next 6 months.”
“Show me my Human Design chart for my birth data.”
“What is the moon phase right now and is it void of course?”

What it gives back to you

You get back plain answers in the chat: planet positions with signs and degrees, lists of dates for transits, moon phase details, or eclipse times. Some tools open a real chart wheel you can click on to see what each planet or house means. If you ask for a comparison, you get both charts side by side with the aspects between them. Everything stays in the conversation so you can keep asking follow-up questions.

Before you start

What you need

A free OpenEphemeris account (signing in through Claude or ChatGPT creates one with 150 free credits)
An API key from your OpenEphemeris dashboard if you install it manually
A client that supports MCP, like Claude Desktop, Claude Web, ChatGPT, Cursor, or Windsurf

Good to know

It uses credits from your OpenEphemeris account, so heavy use can run them down, and some tools are only available on paid plans.

Install it with your AI

Add Open Ephemeris MCP server to your AI, no technical skills needed

You don't install anything by hand. You copy one prompt, paste it into an AI that can work on your computer, and it checks, installs and connects the server for you, asking you when it needs something.

Sign in to get the install prompt

Members get a ready-made prompt that lets the Claude desktop app check Open Ephemeris MCP server, install it and connect it for them, step by step. You don't need any technical skills: you copy, paste and answer a few questions. Your connected AI can also find and install any of the 4,066 MCP servers here for you.