Planetary data · ChronOS guide
Planetary positions API with motion and provenance
A planetary positions API turns an exact time and a set of coordinate options into structured body states. ChronOS also returns the calculation context needed to distinguish tropical from sidereal, geocentric from topocentric and one model release from another.
01 / Method
What defines a planetary position
Longitude alone is ambiguous without a frame and origin. A useful request specifies or inherits a documented coordinate mode, reference frame and correction model. Velocity supports direct, stationary and retrograde classifications, while distance and latitude support additional astronomical and visualization use cases.
Observer-dependent topocentric output requires a WGS84 location. Geocentric output does not silently incorporate a user location.
- Selected celestial body or point
- Exact UTC epoch
- Coordinate origin and reference frame
- Optional WGS84 observer
- Tropical, named ayanamsha or explicit reference offset
02 / API example
Calculate selected planet positions
Use the canonical ephemeris operation and request only the bodies the product needs.
curl --request POST \
--url https://api.chronos-ephemeris.com/v2/ephemeris \
--header "Authorization: Bearer $CHRONOS_API_KEY" \
--header "Content-Type: application/json" \
--data '{
"datetime_utc": "2026-07-16T12:00:00Z",
"bodies": ["sun", "moon", "mercury", "venus", "mars"],
"profile": "chronos.standard@1"
}'Keep API keys in server-side secret storage. The example uses an environment variable and contains no production credential.
03 / Evidence
Interpreting precision
Position accuracy varies by body, epoch, dataset and requested transformation. ChronOS therefore avoids one undifferentiated accuracy number. Its validation material records the tested contract, fixtures and limitations for a release.
For material reliance, retain the result metadata and compare the exact option set used by the application rather than comparing rounded display values.
04 / Applications
Applications of planetary position data
Position and velocity data is the base layer for event detection, charts, sky maps and time-based notifications.
- Celestial maps and orreries
- Transit and ingress alerts
- Natal and return charts
- Retrograde and station timelines
05 / FAQ
Frequently asked questions
Can the API calculate retrograde motion?+
Yes. Body-state velocity supports motion classification, and the event search operation can locate typed station events within a time window.
Does the API support topocentric positions?+
The capability model includes topocentric coordinate options that require an explicit WGS84 observer.
Can I request only the Sun and Moon?+
Yes. The v2 ephemeris request accepts an optional list of canonical body identifiers.