---
title: "Get lunar phase"
method: GET
path: "/ephemeris/moon/phase"
tags: ["lunar"]
---

# Get lunar phase

`GET /ephemeris/moon/phase`

## Request

- Base URL: `https://api.openephemeris.com`
- URL: `https://api.openephemeris.com/ephemeris/moon/phase`
- Auth: one of:
  - HTTP bearer
  - API key in header `X-OpenEphemeris-API-Key`
  - API key in header `X-API-Key`
  - API key in header `X-Service-Key`

Returns lunar phase information for a specific datetime.

**Performance:** <10ms (trigonometric calculation via SuperNOVAS / Calceph)

**Phase Names:** 
- New Moon
- Waxing Crescent
- First Quarter
- Waxing Gibbous
- Full Moon
- Waning Gibbous
- Last Quarter
- Waning Crescent

**Data Returned:**
- Phase name and illumination percentage (0-100%)
- Sun-Moon elongation angle (0-360°)
- Waxing/waning classification
- Moon age in days (~0-29.53 day cycle)
- Moon distance from Earth (km)
- Moon angular diameter (degrees)

**Use Cases:**
- Daily lunar calendars
- Gardening by Moon phase (Full Moon planting, etc.)
- Manifestation/ritual timing (New Moon intentions, Full Moon releases)
- General lunar awareness apps
- Fishing/hunting activity timing

**Example:**
```bash
GET /ephemeris/moon/phase?datetime=2025-12-11T12:00:00Z
```

## Query parameters

- `datetime` string, required: ISO-8601 datetime, e.g. '2025-12-11T12:00:00Z'. A clock time must carry its own zone ('Z' or ±HH:MM); a zone-less clock time is rejected with 400 ambiguous_datetime. A date-only value resolves to 12:00 UTC.
- `format` string: Response format: json | llm.

## Headers

- `authorization` string, nullable
- `X-API-Key` string, nullable
- `X-OpenEphemeris-API-Key` string, nullable
- `apikey` string, nullable

## Response `200`

Successful Response

- LunarPhaseResponse: High-precision lunar phase calculation, indicating the exact illumination percentage, phase angle, and the time remaining until the next key phase.
  - `days_to_full` number: Days until next Full Moon
  - `days_to_new` number: Days until next New Moon
  - `illumination` number, required: Moon illumination percentage (0-100)
  - `metadata` object, required: Calculation metadata
  - `moon_degree` number: The Moon's degree within its sign (0-30).
  - `moon_longitude` number: The Moon's ecliptic longitude in degrees (0-360).
  - `moon_sign` string: Zodiac sign the Moon occupies at this instant (e.g. 'Capricorn'). Also present in metadata.moon_sign for backwards compatibility.
  - `phase_angle` number, required: Sun-Moon angle in degrees (0-360)
  - `phase_name` string, required: Phase name (New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, Waning Crescent)
  - `success` boolean: Calculation success status
  - `waxing` boolean, required: True if Moon is waxing

## Other responses

- `400`: Bad Request
- `422`: Unprocessable Entity - Invalid input format
- `500`: Internal Server Error

---

[API](https://skmtc.dev/openephemeris/apis/open-ephemeris-api.md) · [All operations](https://skmtc.dev/openephemeris/apis/open-ephemeris-api/llms.txt) · [OpenAPI document](https://skmtc.dev/openephemeris/apis/open-ephemeris-api/revisions/d195a769cb89?raw)