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NASA Exoplanets Hill Radius Calculator
x402
NASA Exoplanets Hill Radius Calculator is a paid API for AI agents from exoplanets-nasa.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-30).
Calculates a planet's Hill radius in AU and km from its mass, orbital parameters, and star mass, including stable prograde and retrograde moon regions.
Price / call$0.02
Success—
StatusUnknown
How this service works
Hill radius of a planet in AU and km from its mass, orbit, eccentricity and star mass, with the stable-moon region.
Output
Returns the Hill radius in AU, km, Earth radii, and Jupiter radii; the stable prograde moon region boundary (roughly 1/3 of the Hill radius) in AU and km; and the stable retrograde moon region boundary in AU and km; plus the planet mass expressed in solar masses.
Example use cases
Moon stability check for super-Earth
“I'm studying a super-Earth with 8 Earth masses at 2 AU around a star that's 0.9 solar masses — what's its Hill radius and how far out could a moon stably orbit it?”
Jupiter analog Hill sphere
“Calculate the Hill radius for a Jupiter-mass planet (1 Jupiter mass) at 5.2 AU from a 1 solar mass star with eccentricity 0.05, and tell me the stable prograde and retrograde moon distances.”
Habitable-zone planet moon feasibility
“Could a planet with 3 Earth masses at 0.8 AU from a 0.6 solar mass star realistically host a stable moon? What's its Hill sphere size?”
Technical details
Endpoint
GEThttps://exoplanets-nasa.x402tookit.com/hill-radius?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need precise gravitational sphere-of-influence calculations for exoplanets or solar system bodies — especially to determine whether a moon could exist or remain stable around a given planet. It is the right choice over general orbital mechanics libraries when you want precomputed stable prograde/retrograde boundaries alongside the Hill radius in multiple unit systems, without writing your own physics code.
Side effects
- Missing required parameters (planetMass or orbitAu) returns a validation error
- Planet mass outside the range 0.001–100000 triggers an out-of-bounds error
- Semi-major axis outside 0.001–10000 AU triggers a range error
- Eccentricity of 1.0 or higher (parabolic/hyperbolic orbit) is rejected
- Star mass below 0.05 or above 100 solar masses returns an error
- Payment failure (insufficient USDC balance) returns a 402 response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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