API Reference / lunarPhases · function
Function: lunarPhases()
function lunarPhases(
engine,
jdStart,
jdEnd,
maxHits?): [number, PhaseName][];
Every principal lunar phase (new, first quarter, full, last quarter) within
[jdStart, jdEnd], sorted by time. Found from the Sun–Moon elongation
crossing 0°/90°/180°/270°.
Parameters
| Parameter | Type | Default value | Description |
|---|---|---|---|
engine | Engine | undefined | The engine used to evaluate positions. |
jdStart | number | undefined | Start of the window, Julian Day (UT). |
jdEnd | number | undefined | End of the window, Julian Day (UT). |
maxHits | number | 60 | Cap on the number of phases returned. Defaults to 60. |
Returns
[number, PhaseName][]
Sorted [jdUt, phase] pairs, where phase is one of
PhaseName.
Example
const phases = lunarPhases(engine, julianDay(2025, 1, 1), julianDay(2025, 2, 1));
// [[jd, "new"], [jd, "first_quarter"], ...]