Flat Earth Science in ChatGPT and Claude
What it does
Run the Earth curvature, horizon, flat-map, flight, Sun and daylight calculators, compare a Mercator map with true size and read the verdicts of the tested claims in a chat. The app uses the same calculations as this website and needs no account.
Connect
Server address: https://flatearthscience.org/api/mcp. Transport: Streamable HTTP. Authentication: none.
ChatGPT: open Plugins, choose Add custom MCP server, enter the address above and select no authentication. Claude: open Customize, then Connectors, choose Add custom connector and enter the address.
Tools
| Tool | What it returns |
|---|---|
calculate_curvature | Calculates how much of a distant target the Earth's curvature hides, from the surface distance, the observer's eye height, the target's height and an assumed refraction coefficient. Returns the hidden and visible height, the tangent-plane drop, the horizon distance and dip, the maximum mutual sight-line range and the midpoint bulge on a smooth sphere of radius 6,371.0084 km. |
get_horizon_distance | Gives the distance to the horizon from an eye height above a smooth sphere, and how far a taller object such as a mast stays in straight sight. Returns the observer's horizon distance, the range added by the target height and the maximum shared sightline. |
compare_flat_map_distance | Compares the distance between two cities on a north-polar flat-Earth map with their great-circle distance over a sphere. Returns both distances and the factor by which the map stretches or shrinks the pair. |
get_flight_distance | Calculates the great-circle distance between two places in kilometres, miles and nautical miles, with the initial and final compass bearings. Each end is one of the website's 20 cities or a latitude and longitude. |
get_sun_position | Calculates the Sun's altitude and compass bearing at a place, date and UTC time, with the shadow of a 1 m upright and the day's sunrise and sunset in UTC. A place is one of the website's 20 cities or a latitude and longitude; without a date and time the result is for the current moment. |
get_daylight_hours | Calculates the length of daylight at a place on a date, with sunrise and sunset in UTC, for the UTC day from midnight to midnight. A place is one of the website's 20 cities or a latitude with an optional longitude. |
compare_true_size | Shows how much a Mercator map distorts a country's area, from its real area and the latitude it is drawn at. Returns the real area, the area multiplier at the country's own latitude and at a chosen latitude, and the size it appears at each. Covers the nine countries and regions in the website's size table. |
find_claims | Searches the website's tested claims and flat-earth investigations, or returns one by id. Each result gives the claim, the verdict, the key evidence and the link to its page; an empty query lists all of them. |
Example prompts
- How much of a 10 m lighthouse is hidden by the curve of the Earth over 20 km, seen from 2 m?
- How far apart are Sydney and Santiago on the flat Earth map compared with the real distance?
- What is the verdict on the Bermuda Triangle?
Your data
The app only reads. Nothing you ask is stored, and following a link from a result to this website records no click. See the privacy page and the terms.
Troubleshooting
If the tools do not appear, check that the address above is entered exactly, with no authentication, then refresh the connector or start a new chat. A place is one of the website's 20 cities or a latitude and longitude. Sunrise, sunset and the Sun's position are given in UTC.
Support
Questions or problems: support@flatearthscience.org.