Secondary Progressions

Compute a secondary progressed chart. Secondary progressions use the "day-for-a-year" method: each day after birth corresponds to one year of life. The progressed chart for age 30 is computed using the planetary positions 30 days after birth.

GET  /v1/progressed
POST /v1/progressed

Credit cost: 2

Parameters

The target_datetime must be after the natal datetime. If the target precedes the birth date, the API returns invalid_progression.

How it works

For someone born on June 15, 1990, requesting progressions for March 20, 2024:

1. Calculate elapsed time — 2024-03-20 minus 1990-06-15 = 12331.23 days
2. Convert to days — one day for every 365.25 days: 12331.23 / 365.25 = 33.76 days
3. Compute progressed datetime — 1990-06-15 18:30 + 33.76 days = 1990-07-19 12:46 UTC
4. Cast a natal chart for that instant at the natal location — exactly what /v1/positions and /v1/houses return there

In Julian Days: progressed = natal + (target − natal) / 365.25. A target exactly 365.25 days after birth progresses the chart by exactly one day, and a target at the birth instant returns the natal chart.

The progressed chart shows the slow evolution of the natal chart over a lifetime. The progressed Moon moves roughly 1° per month (12° per year), while the progressed Sun moves about 1° per year.

Response

The response has the same structure as /v1/natal-chart, with chart_type set to "progressed" and metadata.source recording the natal and target instants.

{
  "data": {
    "chart_type": "progressed",
    "positions": [ "..." ],
    "houses": { "..." },
    "aspects": [ "..." ],
    "parallels": [],
    "metadata": {
      "datetime": 2448092.031899,
      "datetime_iso": "1990-07-19T12:45:56.124Z",
      "location": { "latitude": 40.7128, "longitude": -74.006, "altitude": 0.0 },
      "source": { "type": "progressed", "natal_datetime": 2448058.2708335, "target_datetime": 2460389.5000012 },
      "..."
    }
  },
  "meta": { "..." }
}

metadata.datetime is the progressed instant the chart was cast for (not the target date).

Examples

Current progressions for a 1990 birth

curl "https://api.morphemeris.com/v1/progressed?\
datetime=1990-06-15T18:30:00Z&lat=40.7128&lon=-74.006\
&target_datetime=2024-03-20T00:00:00Z" \
  -H "Authorization: Bearer morphemeris_live_YOUR_KEY"

const res = await fetch(
  "https://api.morphemeris.com/v1/progressed?" + new URLSearchParams({
    datetime: "1990-06-15T18:30:00Z", lat: "40.7128", lon: "-74.006",
    target_datetime: "2024-03-20T00:00:00Z",
  }),
  { headers: { Authorization: "Bearer morphemeris_live_YOUR_KEY" } }
);
const { data } = await res.json();

import requests

res = requests.get(
    "https://api.morphemeris.com/v1/progressed",
    params={
        "datetime": "1990-06-15T18:30:00Z", "lat": 40.7128, "lon": -74.006,
        "target_datetime": "2024-03-20T00:00:00Z",
    },
    headers={"Authorization": "Bearer morphemeris_live_YOUR_KEY"},
)
data = res.json()

Tips

• The progressed Moon is the fastest-moving body in progressions — track it to find when it changes sign or aspects natal planets.
• Progressed houses change very slowly. Some astrologers ignore progressed houses entirely and only interpret progressed planetary positions against the natal chart.
• To compare progressed positions to natal positions, use /v1/synastry with the progressed datetime as one chart and the natal datetime as the other.