# Calendar Systems Moon Phase

> Calendar Systems Moon Phase is a paid API for AI agents from calendar-systems.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-31).

Returns moon phase name, age in days, illumination fraction, and previous/next lunar event times (new moon, quarters, full moon) for a given date.

## Facts

- Endpoint: GET https://calendar-systems.x402tookit.com/moon-phase?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/calendar-systems-moon-phase-5fb2e54a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_6T5EHBstUevrgFd5SSCAJ

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 calendar-systems-moon-phase-5fb2e54a
```

Example prompt: What's the moon phase on July 4th 2025? I want to know the phase name, how many days old the moon is, the illumination fraction, and when the next full moon and next new moon will be.

## When to prefer this

Choose this endpoint when you need detailed lunar phase data for a single specific date, including illumination, age, waxing/waning status, and surrounding lunar event times. Prefer this over a bulk lunar events endpoint when you only need the context around one date rather than all moon phases in a month.

## Known failure modes

- Date out of supported range (1900–2100) returns an error or degraded result
- Invalid date format causes a validation error
- Missing required 'date' query parameter returns a bad request error
- Time parameter in wrong format (not HH:MM) may default to 12:00 or return an error
- Network or service unavailability returns no response

## How this service works

Moon phase name, age in days, approximate illumination and the previous/next new, quarter and full moon times for a date.

## Output

Returns a JSON object with the moon's phase name (e.g. 'Waxing Crescent'), age in days since last new moon, illumination fraction (0–1), waxing boolean, elongation in degrees, ISO datetime strings for the previous new moon, previous full moon, next new moon, next first quarter, next full moon, next last quarter, lunation length in days, mean synodic month in days, and metadata fields like timeBasis and disclaimer.

## 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": [
      "date"
     ],
     "properties": {
      "date": {
       "type": "string",
       "description": "YYYY-MM-DD, 1900 to 2100"
      },
      "time": {
       "type": "string",
       "description": "UTC time HH:MM, default 12:00"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "phase": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "waxing": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "ageDays": {
       "type": [
        "null",
        "number"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "weekday": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "timeBasis": {
       "type": [
        "null",
        "string"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "nextNewMoon": {
       "type": [
        "null",
        "string"
       ]
      },
      "nextFullMoon": {
       "type": [
        "null",
        "string"
       ]
      },
      "elongationDeg": {
       "type": [
        "null",
        "number"
       ]
      },
      "nextLastQuarter": {
       "type": [
        "nul
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/calendar-systems-moon-phase-5fb2e54a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from calendar-systems.x402tookit.com](https://www.zero.xyz/host/calendar-systems.x402tookit.com/llms.txt)