Solar Arc Directions API

From the birth data and a target date the endpoint first progresses the chart day-for-a-year, measures how far the progressed Sun has moved from its natal position, and takes that distance as the arc. It then adds the arc to every natal longitude at once: all planets, all house cusps, the ascendant and the MC. The response carries the directed positions under data.planets and data.houses, the arc itself in degrees under data.arc, and the key that produced it under data.key. Because a single arc is applied uniformly, the geometry of the natal chart is preserved and only its relationship to the natal degrees changes, which is what makes the technique so economical to read: one number tells you the state of the entire chart at a given age. Two other keys are available on the same endpoint. Set key to naibod for the mean solar rate of 59'08.3" per year, or omit it for the plain one degree per year. Sending converse true directs backwards from the birth moment instead of forwards, reversing the sign of the arc.

curl -X POST https://api.astroway.info/v1/symbolic-directions \
  -H "X-Api-Key: aw_live_..." \
  -H "Content-Type: application/json" \
  -d '{
  "date": "1990-05-15",
  "time": "14:30:00",
  "timezoneOffset": 3,
  "latitude": 50.45,
  "longitude": 30.52,
  "targetDate": "2026-05-15",
  "key": "solar_arc"
}'

{
  "ok": true,
  "data": {
    "arc": 34.5083,
    "key": "solar_arc",
    "planets": [
      {
        "id": 0,
        "name": "Sun",
        "longitude": 88.8843,
        "isRetrograde": false
      }
    ],
    "houses": {
      "system": "P",
      "ascendant": 204.4763,
      "mc": 111.5826
    }
  }
}

Reach for solar arc when you need timing that is symbolic rather than astronomical, and when you want it in a form a reader can follow. Because everything moves at one rate, a directed contact lands on a specific year rather than a window, which suits a life-timeline feature, an age-milestone report, or an AI narrative that has to say what a given year is about. It pairs naturally with secondary progressions, since the arc is derived from the same progressed Sun: progressions give you the moving inner chart, solar arc gives you the whole chart translated forward. Compare the three keys when precision matters to your audience. Solar arc follows the actual Sun and so varies slightly by birth date, Naibod uses the mean rate, and one degree per year is the round-number convention. For a mid-May birth the three come out at roughly 34.5, 35.5 and 36.0 degrees over 36 years, close enough to agree on the decade and far enough apart to name different years.

The arc is the distance travelled by the secondary-progressed Sun, day for a year, which is the standard definition; the Naibod key uses the mean daily motion of the Sun, 59'08.3" per year. For solar arc the progressed chart is computed forwards and the direction of travel is applied once, so converse directions return the arc negated rather than doubled. Positions come from the Swiss Ephemeris engine in the tropical zodiac, on the same bodies and house system as the natal endpoints.