Synastry

Compute synastry (chart comparison) between two natal charts. Returns both individual charts plus inter-chart aspects and parallels — the angular relationships between bodies in chart A and bodies in chart B.

Text

GET  /v1/synastry
POST /v1/synastry

Credit cost: 3

Parameters

This endpoint uses _a and _b suffixes for the two charts' datetime and location parameters.

Parameter	Type	Required	Default	Description
`datetime_a`	string	One of `datetime_a` or `jd_a`	—	Person A: ISO 8601 UTC datetime
`jd_a`	number	One of `datetime_a` or `jd_a`	—	Person A: Julian Day in UT1
`lat_a`	number	Yes	—	Person A: latitude
`lon_a`	number	Yes	—	Person A: longitude
`datetime_b`	string	One of `datetime_b` or `jd_b`	—	Person B: ISO 8601 UTC datetime
`jd_b`	number	One of `datetime_b` or `jd_b`	—	Person B: Julian Day in UT1
`lat_b`	number	Yes	—	Person B: latitude
`lon_b`	number	Yes	—	Person B: longitude
`bodies`	string	No	`"planets"`	Comma-separated body names (same for both charts)
`system`	string	No	`"placidus"`	House system
`sidereal`	string	No	—	Ayanamsha for sidereal mode
`aspects`	string	No	Major 7	Comma-separated aspect types
`orb`	number	No	—	Global orb override in degrees
`applying`	boolean	No	`false`	Include applying/separating flag
`parallels`	boolean	No	`false`	Include declination parallels
`parallel_orb`	number	No	`1.0`	Orb for parallels in degrees

Response

JSON

{
  "data": {
    "chart_a": {
      "metadata": { "..." },
      "bodies": [ "..." ],
      "houses": { "..." }
    },
    "chart_b": {
      "metadata": { "..." },
      "bodies": [ "..." ],
      "houses": { "..." }
    },
    "inter_aspects": [
      {
        "body_a": "sun",
        "body_b": "venus",
        "aspect": "conjunction",
        "angle": 0.0,
        "orb": 3.12,
        "applying": false
      }
    ],
    "inter_parallels": []
  },
  "meta": { "..." }
}

Field	Type	Description
`chart_a`	object	Full chart data for person A (same structure as `/v1/natal-chart`)
`chart_b`	object	Full chart data for person B
`inter_aspects[]`	array	Aspects between bodies in chart A and bodies in chart B
`inter_parallels[]`	array	Declination parallels between charts (when `parallels=true`)

In inter_aspects, body_a always refers to a body from chart A, and body_b to a body from chart B.

Examples

Two-person synastry

Bash

curl "https://api.morphemeris.com/v1/synastry?\
datetime_a=1990-06-15T18:30:00Z&lat_a=40.7128&lon_a=-74.006\
&datetime_b=1988-03-22T10:00:00Z&lat_b=51.5074&lon_b=-0.1278" \
  -H "Authorization: Bearer morphemeris_live_YOUR_KEY"

javascript

const params = new URLSearchParams({
  datetime_a: "1990-06-15T18:30:00Z", lat_a: "40.7128", lon_a: "-74.006",
  datetime_b: "1988-03-22T10:00:00Z", lat_b: "51.5074", lon_b: "-0.1278",
});
const res = await fetch(
  `https://api.morphemeris.com/v1/synastry?${params}`,
  { headers: { Authorization: "Bearer morphemeris_live_YOUR_KEY" } }
);
const { data } = await res.json();

Python

import requests

res = requests.get(
    "https://api.morphemeris.com/v1/synastry",
    params={
        "datetime_a": "1990-06-15T18:30:00Z", "lat_a": 40.7128, "lon_a": -74.006,
        "datetime_b": "1988-03-22T10:00:00Z", "lat_b": 51.5074, "lon_b": -0.1278,
    },
    headers={"Authorization": "Bearer morphemeris_live_YOUR_KEY"},
)
data = res.json()

With parallels and applying flag

Bash

curl "https://api.morphemeris.com/v1/synastry?\
datetime_a=1990-06-15T18:30:00Z&lat_a=40.7128&lon_a=-74.006\
&datetime_b=1988-03-22T10:00:00Z&lat_b=51.5074&lon_b=-0.1278\
&parallels=true&applying=true" \
  -H "Authorization: Bearer morphemeris_live_YOUR_KEY"

Synastry

Synastry

Parameters

Response

Examples

Two-person synastry

With parallels and applying flag

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