Send a date, a place, and what you want to know. Get back positions, phases, rise and set times, eclipse circumstances, and what's visible tonight — planet and Moon positions computed on JPL DE441, the same ephemeris professional observatories use, not a low-order approximation.
Pick a tab, fill in a date and place, hit run — every tab calls the real API and shows the JSON it returns. Each panel opens with a recorded response so you can see the exact shape before you even click; if the gateway isn't reachable from where you're viewing, it falls back to that same recorded response.
Every claim here traces to a named ephemeris or catalog, not a marketing estimate.
| Capability | Cycles Arc Astronomy API | Typical astronomy API |
|---|---|---|
| Planet & Moon positions | JPL DE441 ephemeris, honestly labeled | Low-order analytic approximation |
| Eclipses | Solar & lunar, with local circumstances and ground path | Often not offered, or dates only |
| Catalogs | Stars, deep-sky objects, and constellations built in | Frequently a separate paid product |
| Meteor showers | Active showers, radiant altitude, and Moon interference | Rarely available |
| Access model | Single GET call, JSON response | Varies |
The playground demos six of these. Every verb below is live on the API today — same date-and-place in, flat JSON out.
A body name, a date and hour, and a latitude/longitude — plain query parameters, no payloads.
Positions come from JPL DE441 (analytic fallback labeled); catalog queries hit the star, deep-sky, and constellation datasets directly.
Coordinates are transformed to altitude and azimuth for your exact place and moment, with rise/set and visibility resolved.
Flat, predictable fields — including which ephemeris was used, so you always know the basis of the number.
Tell users what's up tonight, when the Moon rises, and when the next eclipse or meteor shower is visible from where they are.
Drop-in planet positions and star/DSO/constellation data without shipping your own ephemeris or catalog.
Answer "where is Mars", "what phase is the Moon", "when's the next eclipse" for any place and date, on demand.
Combine visibility, Moon interference, and meteor-shower timing to plan a session around real sky conditions.
{
"planet": "Mars",
"lon": 91.033433,
"lat": 0.256927,
"distance_au": 1.945908514,
"retrograde": 0
}
Flat JSON — the daemon's own fields, nothing wrapped. Ask for body=sun or body=moon with lat/lon and the response also carries declination and alt/az for your place.
ephemeris field telling you which was used, so you're never guessing about the basis of a number./v1/meteor/showers lists active showers for a date with peak ZHR, and /v1/meteor/shower adds radiant altitude and Moon interference for your exact place and time.