New Numerology API

Planet condition and strength

Retrograde (vakri) in Vedic astrology

A planet is retrograde, or vakri, when it appears from Earth to move backward through the zodiac for a while. It is an effect of the Earth and the planet moving at different speeds around the Sun. The API marks it with a retrograde flag and a negative speed. Rahu and Ketu are always reported as retrograde, following tradition.

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© API for Astrology (apiforastrology.com). "Glossary houses chart". All rights reserved. Not to be copied or reused.123456789101112A North Indian chart has 12 houses

Retrograde: how the API computes it

The API marks a planet retrograde when its speed along the zodiac is below zero (CH-10). POST /v1/planets returns a retrograde flag and the speed, in degrees a day, for each planet. The Sun and the Moon are never retrograde.

Rahu and Ketu are always marked retrograde, as tradition treats them. Their speed field still shows their real motion. With the true node, the default, that motion is sometimes forward.

A planet slows down, seems to stop, turns back, then stops again and goes forward. The two turning moments are called stations. GET /v1/sky/events lists retrograde periods with their stations for a date range.

A station is a single moment, so the calendar date it falls on depends on the time zone (AN-03). Retrograde motion changes other results too. Mercury's combustion distance drops from 14 to 12 degrees, and Venus's from 10 to 8 (CH-07).

In shadbala, the six-part strength score, retrograde is the strongest kind of motion (SB-05). A retrograde planet can also slip back into the sign it just left. POST /v1/transits/ingresses/{graha} shows that return as its own row, with resumes_visit set to true.

Get it from the API

Planet positions and the ascendant. Here is the call to API for Astrology (apiforastrology.com) for our sample, John Doe, born Aug 15, 1990, 10:30 AM, New York.

POST /v1/planets

# John Doe, born Aug 15, 1990, 10:30 AM, New York
curl -X POST "https://apiforastrology.com/api/astrology/v1/planets" \
  -H "Authorization: Bearer $ASTROLOGY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"year":1990,"month":8,"day":15,"hour":10,"minute":30,"second":0,"latitude":40.7128,"longitude":-74.006,"timezone":"America/New_York"}'
Answer (long lists shortened)200 OK
{
  "meta": {
    "ayanamsa": "lahiri",
    "ayanamsa_value": 23.7260727,
    "julian_day": 2448119.10483,
    "ephemeris": "JPL DE440s",
    "node": "true",
    "timezone": {
      "source": "zone",
      "offset_hours": -4,
      "zone": "America/New_York",
      "abbreviation": "EDT",
      "dst": true,
      "dst_hours": 1,
      "ambiguous_resolved_by_fold": null,
      "note": "read from the IANA tz database at this instant, so daylight saving and historical offset changes are included"
    }
  },
  "ascendant": {
    "name": "Ascendant",
    "longitude": 169.934155,
    "sign": "Virgo",
    "sign_number": 6,
    "degree_in_sign": 19.934155,
    "degree_dms": "19 : 56 : 03",
    "house": 1,
    "nakshatra": "Hast",
    "nakshatra_lord": "Moon",
    "pada": 3,
    "speed": 0,
    "retrograde": false,
    "combust": false,
    "dignity": "n/a",
    "vargottama": false,
    "pushkara": {
      "navamsa": false,
      "navamsa_number": 6,
      "bhaga": false,
      "bhaga_degree": 9,
      "bhaga_by_element": false,
      "bhaga_degree_by_element": 14,
      "sources_agree": true,
      "orb_degrees": 1
    }
  },
  "positions": [
    {
      "name": "Sun",
      "longitude": 118.7753409,
      "sign": "Cancer",
      "sign_number": 4,
      "degree_in_sign": 28.7753409,
      "degree_dms": "28 : 46 : 31",
      "house": 11,
      "nakshatra": "Ashlesha",
      "nakshatra_lord": "Mercury",
      "pada": 4,
      "speed": 0.9610665,
      "retrograde": false,
      "combust": false,
      "dignity": "friend",
      "vargottama": false,
      "pushkara": {
        "navamsa": false,
        "navamsa_number": 9,
        "bhaga": false,
        "bhaga_degree": 8,
        "bhaga_by_element": false,
        "bhaga_degree_by_element": 7,
        "sources_agree": true,
        "orb_degrees": 1
      }
    },
    {
      "name": "Moon",
      "longitude": 54.5750352,
      "sign": "Taurus",
      "sign_number": 2,
      "degree_in_sign": 24.5750352,
      "degree_dms": "24 : 34 : 30",
      "house": 9,
      "nakshatra": "Mrigashira",
      "nakshatra_lord": "Mars",
      "pada": 1,
      "speed": 14.258194,
      "retrograde": false,
      "combust": false,
      "dignity": "mulatrikona",
      "vargottama": false,
      "pushkara": {
        "navamsa": false,
        "navamsa_number": 8,
        "bhaga": false,
        "bhaga_degree": 14,
        "bhaga_by_element": false,
        "bhaga_degree_by_element": 14,
        "sources_agree": true,
        "orb_degrees": 1
      }
    },
    {
      "name": "Mars",
      "longitude": 27.7149328,
      "sign": "Aries",
      "sign_number": 1,
      "degree_in_sign": 27.7149328,
      "degree_dms": "27 : 42 : 54",
      "house": 8,
      "nakshatra": "Krittika",
      "nakshatra_lord": "Sun",
      "pada": 1,
      "speed": 0.5753266,
      "retrograde": false,
      "combust": false,
      "dignity": "own sign",
      "vargottama": false,
      "pushkara": {
        "navamsa": true,
        "navamsa_number": 9,
        "bhaga": false,
        "bhaga_degree": 21,
        "bhaga_by_element": false,
        "bhaga_degree_by_element": 21,
        "sources_agree": true,
        "orb_degrees": 1
      }
    }
  ],
  "planetary_war": []
}

Where the API returns it

POST/v1/planetsPlanet positions and the ascendant
POST/v1/chart/svgThe birth chart or any divisional chart as an SVG or PNG image
POST/v1/forecast/annualYearly forecast: a year of sky events read against a chart
POST/v1/transitsCurrent transits read against a chart
GET/v1/skyPlanet positions at a moment, no chart
GET/v1/sky/eventsCalendar of sky events, no chart

What the API reference says

Each line is quoted from the reference page of the endpoint named above it.

  • POST /v1/chart/svg · The birth chart or any divisional chart as an SVG or PNG imageA planet moving backward (retrograde) is marked R.
  • POST /v1/forecast/annual · Yearly forecast: a year of sky events read against a chartThe events are ingresses (a planet entering a new sign) and retrograde periods (a planet appearing to move backward).

Feature page: Planetary strength. Who uses it: Astrologer consultation platforms. The classical rules the API follows are in the rulebook.

How we check the numbers

Every value here starts from planet positions worked out from NASA JPL planet data (DE440). We test them against NASA JPL Horizons, NASA's planet position service. On 25,571 positions from 1850 to 2149, the Sun and planets agree within 0.001 arc seconds. The Moon agrees within 0.011. On 2,000 random birth charts, the rising sign agrees with Swiss Ephemeris within 0.004 arc seconds. An arc second is 1/3,600 of a degree. A practicing astrologer reviews the rules behind these answers. See how we test.

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Astrology API

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Your first answer

John Doe, New York

POST /v1/planets200 OK
  • RisingVirgoHast
  • SunCancerAshlesha
  • MoonTaurusMrigashira
  • MarsAriesKrittika

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