Gravitational field strength
API · /gravitation-api
Gravitation & Weight API
healthy
4,813 Subscribers
Newtonian gravitation as an API, computed locally and deterministically. The force endpoint applies Newton's law of universal gravitation, F = G·m1·m2/r² — the attractive force between two masses a distance apart, with G = 6.6743×10⁻¹¹ — and solves for whichever of the two masses, the separation or the force you leave out (the Earth and Moon pull on each other with about 2×10²⁰ newtons). The field endpoint gives the gravitational field strength g = G·M/r² at a distance from a mass, or the surface gravity of a built-in body (the Sun, the planets, the Moon and major moons), as a multiple of Earth gravity, and the weight of a test mass placed there. The weight endpoint tells you what something weighs on another world, W = m·g_body — your weight on the Moon, Mars or Jupiter — from a mass or your Earth weight, with the ratio to Earth. Everything is computed locally and deterministically, so it is instant and private. Ideal for physics and astronomy-education tools, space and planetary apps, science museums and games, and engineering. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is gravitational force, field and weight; for orbital speed, period and escape velocity use an orbital-mechanics API.
api.oanor.com/gravitation-api
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 87 ms
- Server probes · 24h
- Subscribers
- 4,813
- active
- Total calls
- 32
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 3,000 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- Newton's law of universal gravitation F=G*m1*m2/r^2
- Deterministic, instant local compute
- SI units (kg, m, newtons)
- 3,000 calls/month
Starter
€5.00 /month
- 40,000 calls / month
- 5 requests / second
- Hard cap (429 above quota, no overage)
- Force, field-strength and surface-gravity endpoints
- Two-body and point-mass calculations
- Configurable G precision
- 40,000 calls/month
Pro
€15.00 /month
- 250,000 calls / month
- 15 requests / second
- Hard cap (429 above quota, no overage)
- Batch multi-pair force computation
- Planetary weight conversions across bodies
- Orbital-period & escape-velocity helpers
- 250,000 calls/month
Mega
€49.00 /month
- 1,535,000 calls / month
- 40 requests / second
- Hard cap (429 above quota, no overage)
- High-throughput classroom & app workloads
- Full astronomy preset body catalog
- Priority compute lane
- 1,500,000 calls/month
Built by
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api.oanor.com/unit-api
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api.oanor.com/parallax-api
Light Travel Time API
Light-travel-time astronomy maths as an API, computed locally and deterministically. The travel-time endpoint computes how long light takes to cross a distance, t = d/c with c = 299,792,458 m/s exactly, accepting the distance in metres, kilometres, miles, astronomical units, light-years, parsecs or light-seconds/minutes and returning the time in seconds, minutes, hours, days and years — light from the Sun reaches Earth in about 8.3 minutes and the nearest star is about 4.2 light-years away. The distance endpoint inverts the relation, d = c·t, to give how far light travels in a time, returning the distance in metres, kilometres, astronomical units, light-years and parsecs — one light-year is about 9.461×10¹⁵ m. The round-trip endpoint computes the one-way and round-trip communication delay to a target, d/c and 2·d/c, the light-speed latency that makes distant spacecraft control so slow and Mars rovers largely autonomous. Distance units include light-second and light-minute and time units run from seconds to years. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy, space-mission, education, science-communication and simulation app developers, communication-delay and cosmic-distance tools, and physics teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is light travel time; for an object's angular size use an angular-size API and for sidereal time a sidereal API.
api.oanor.com/lighttime-api
Angular Size API
Angular-size astronomy and optics maths as an API, computed locally and deterministically. The angular-size endpoint computes the angular diameter an object subtends, δ = 2·arctan(d/(2D)), from its physical size and its distance, returning the angle in radians, degrees, arcminutes and arcseconds, along with the small-angle approximation δ ≈ d/D — the Sun and Moon are each about half a degree (31 arcminutes) across. The distance endpoint inverts the relation, D = d/(2·tan(δ/2)), to give an object's distance from its known true size and its measured angular size, the basis of the standard-ruler distance method. The object-size endpoint computes an object's physical diameter, d = 2·D·tan(δ/2), from its distance and angular size. Size and distance use any one consistent unit, and angles may be given in radians, degrees, arcminutes or arcseconds. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy, telescope, astrophotography, surveying and optics app developers, field-of-view and rangefinding tools, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is angular size; for stellar magnitude and parallax distance use a star-magnitude API and for sidereal time a sidereal API.
api.oanor.com/angularsize-api
Frequently asked questions
Quick answers about pricing, quotas, and integration.
How do I get an API key for Gravitation & Weight API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Gravitation & Weight API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Gravitation & Weight API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Gravitation & Weight API cost?
Gravitation & Weight API has a free tier with 100 calls / month. Paid plans start at €5.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Gravitation & Weight API GDPR-compliant?
All requests to Gravitation & Weight API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.
Pick an endpoint from the list on the left to see its details and try it.
Code snippets
Sign up to get an API key, then call any path under your slug.
curl https://api.oanor.com/gravitation-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."const res = await fetch("https://api.oanor.com/gravitation-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();$ch = curl_init("https://api.oanor.com/gravitation-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);import requests
r = requests.get(
"https://api.oanor.com/gravitation-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())Ratings
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