Planetary Midpoints

What is the Planetary Midpoints endpoint?

You need the midpoint between every pair of planets and angles in a birth chart. The Planetary Midpoints endpoint takes birth data and returns 153 calculated midpoints (every pairwise combination of major chart points) with the planet pair, exact ecliptic degree, zodiac sign, sign-relative position, and house placement for each.

This endpoint is part of the Natal Chart API.

Why does this endpoint exist?

You are building Cosmobiology, Uranian astrology, or hybrid-modern features that work with midpoints. A midpoint is the halfway point between two bodies on the ecliptic; planets that aspect a midpoint activate the energy of both endpoints. Computing 153 midpoints by hand means iterating every pair of bodies, averaging their longitudes, and looking up the resulting sign and house. This endpoint runs all of that in one call.

What inputs does it need?

You pass standard birth data: API key, full name, date components, time components, gender, place, decimal latitude and longitude, and timezone offset from UTC. No house_system parameter is needed, since midpoint positions are derived from the underlying planet and angle positions. Authentication uses a Bearer token in the Authorization header.

What does the response data look like?

You get an envelope with status, code, message, and data. The data array carries 153 midpoint objects, one for every unique planet pair across the major chart points (Sun, Moon, planets, Ascendant, Midheaven, and lunar nodes). Each object names both endpoints in planet_pair and reports the calculated midpoint position.

What does a real response look like?

Below is a slice of the response for a sample birth (24 May 2023, 14:40:43 IST, New Delhi). The full response includes 153 entries; this slice shows the first five Ascendant-paired midpoints to keep the example readable.

{
  "status": "success",
  "code": 200,
  "message": "Request successful",
  "data": [
    {
      "planet_pair": ["Ascendant", "Sun"],
      "full_degree": 124.343447,
      "sign": "Leo",
      "sign_no": 5,
      "longitude": "4:20:36",
      "house": 10
    },
    {
      "planet_pair": ["Ascendant", "Moon"],
      "full_degree": 151.5101632,
      "sign": "Virgo",
      "sign_no": 6,
      "longitude": "1:30:36",
      "house": 11
    },
    {
      "planet_pair": ["Ascendant", "Mars"],
      "full_degree": 153.9280131,
      "sign": "Virgo",
      "sign_no": 6,
      "longitude": "3:55:40",
      "house": 11
    },
    {
      "planet_pair": ["Ascendant", "Mercury"],
      "full_degree": 112.3730441,
      "sign": "Cancer",
      "sign_no": 4,
      "longitude": "22:22:22",
      "house": 10
    },
    {
      "planet_pair": ["Ascendant", "Venus"],
      "full_degree": 146.8109554,
      "sign": "Leo",
      "sign_no": 5,
      "longitude": "26:48:39",
      "house": 11
    }
  ]
}

What can you build with this endpoint?

You use Planetary Midpoints whenever your product targets Cosmobiology, Uranian astrology, or interpretation features that treat planet pairs as energetic combinations rather than individual placements. The full 153-midpoint set covers every pairwise combination of major chart points, so you get the complete midpoint matrix in a single call.

1. Midpoint trees and dial UIs. Render a 90-degree dial with all 153 midpoints plotted, the standard Cosmobiology visualization for spotting clusters.
2. Aspecting-planet detection. Cross-reference each midpoint's full_degree against planet positions to surface "Sun = Mars/Saturn" style midpoint structures.
3. Sun/Moon midpoint highlights. The Sun/Moon midpoint is the most-cited midpoint in modern astrology. Pre-fetch and surface it as a dedicated panel in your chart UI.
4. Pair-focused interpretive content. Render selected midpoints (Mercury/Venus for thinking style, Mars/Saturn for ambition, Jupiter/Saturn for life direction) with prose drawn from your own content layer.

How accurate is the calculation?

You are computing 153 averaged positions across the major chart points. The underlying Sun, Moon, planet, and angle positions come from Swiss Ephemeris with NASA JPL ephemeris data. Midpoints are computed by averaging the two endpoints' ecliptic longitudes and reducing modulo 360, so accuracy inherits directly from the source positions: arc-second precision on every endpoint, arc-second precision on the midpoint.

House placement of each midpoint depends on the chart's house cusps, computed via Placidus by default. Birth time precision matters here as much as it does for any house-based feature.

How does this relate to the parent API?

You are layering midpoint analysis on top of the standard birth chart. This endpoint complements the Natal Chart API by providing pre-computed midpoints across every pair of major chart points in one call.

Planetary Positions returns the underlying body positions; this endpoint averages every pair. The Aspect Table can then be queried separately to find which planets aspect which midpoints, which is the core of midpoint-based interpretation. Combine the three endpoints for full Cosmobiology or Uranian-style chart analysis.

Summary

The Planetary Midpoints endpoint returns 153 calculated midpoints across every pairwise combination of major chart points, each with sign, ecliptic degree, and house placement. It runs on Swiss Ephemeris with NASA JPL ephemeris data and inherits arc-second precision from the underlying positions. Use it for Cosmobiology, Uranian astrology, midpoint trees, and any interpretation feature that treats planet pairs as combined energies.