# NASA Exoplanets: Habitable Zone Calculator

> NASA Exoplanets: Habitable Zone 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).

Computes inner and outer habitable-zone edges in AU for a star using the Kopparapu 2013 model, and classifies where a given orbit falls relative to those zones.

## Facts

- Endpoint: GET https://exoplanets-nasa.x402tookit.com/habitable-zone?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/nasa-exoplanets-habitable-zone-calculator-479c64ae
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_n7aWYzs-jj8x1KH9d9cXs

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability nasa-exoplanets-habitable-zone-calculator-479c64ae
```

Example prompt: Using the Kopparapu 2013 model, calculate the habitable zone boundaries for a star with an effective temperature of 5778 K and luminosity of 1 solar unit, and tell me whether a planet at 1 AU falls inside the conservative or optimistic zone.

## When to prefer this

Choose this endpoint when you need the Kopparapu 2013 habitable zone model specifically — it provides both optimistic and conservative zone edges from stellar effective temperature plus either luminosity or radius, and can immediately classify any supplied orbit. Prefer this over generic calculators when you need a scientifically grounded, citable model result with zone placement verdict and degraded-flag transparency.

## Known failure modes

- Missing required teffK parameter returns a validation error
- Stellar temperature outside 2600–7200 K fitted range returns degraded/extrapolated results with a warning flag
- Neither luminositySolar nor radiusSolar provided alongside teffK may cause degraded luminosity estimation
- orbitAu and periodDays/massSolar cannot both be absent if a zone placement verdict is desired — the orbit verdict is skipped
- Values outside physically plausible ranges may produce unexpected or nonsensical zone boundaries

## How this service works

Habitable-zone edges in AU for a star from luminosity or radius, plus temperature (Kopparapu 2013), and where an orbit falls.

## Output

Returns the conservative and optimistic habitable zone inner and outer edges in AU (Kopparapu 2013 model), the derived stellar luminosity and its source, and — if an orbit was supplied — a verdict string classifying whether the orbit is inside the conservative zone, inside the optimistic zone, or outside both, plus a human-readable summary and any caveats or disclaimer notes.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "teffK"
     ],
     "properties": {
      "teffK": {
       "type": "number",
       "description": "Star effective temperature in K, 2000 to 10000 (model fitted for 2600 to 7200)"
      },
      "orbitAu": {
       "type": "number",
       "description": "Planet semi-major axis in AU, to place it against the zone"
      },
      "massSolar": {
       "type": "number",
       "description": "Star mass in solar masses, used with periodDays"
      },
      "periodDays": {
       "type": "number",
       "description": "Orbital period in days (with massSolar, instead of orbitAu)"
      },
      "radiusSolar": {
       "type": "number",
       "description": "Star radius in solar radii (used with teffK when luminosity is not given)"
      },
      "luminositySolar": {
       "type": "number",
       "description": "Star luminosity in solar units (give this, or radiusSolar)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "teffK": {
       "type": [
        "null",
        "number"
       ]
      },
      "method": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "orbitAu": {
       "type": [
        "null",
        "number"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "position": {
       "type": [
        "null",
        "string"
       ]
      },
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/nasa-exoplanets-habitable-zone-calculator-479c64ae/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from exoplanets-nasa.x402tookit.com](https://www.zero.xyz/host/exoplanets-nasa.x402tookit.com/llms.txt)