Phases of the Moon

Calculations run in this browser with Astronomy Engine 2.1.19 (MIT license). Times use the selected IANA zone or a documented UTC offset. For ancient records, a modern city zone does not establish the historical clock convention. Gregorian and Julian dates are explicit; output dates and the lunar calendar use Gregorian. There is no modern-era date cutoff, but accepting a distant date is not a guarantee of modern-era precision.

Phase events occur at Sun–Moon ecliptic longitude differences of 0°, 90°, 180° and 270°. Illumination is the visible fraction of the Moon’s sunlit disc, not that longitude angle. The calendar’s diagrams sample local noon; its event labels mark the actual event’s local civil date. The large diagram uses the selected instant. Phase orientation is schematic, not a simulation of the observer’s sky.

Lunar eclipse peaks, types and durations use Astronomy Engine’s lunar eclipse search. Penumbral, partial and total eclipses are included. These are global events, not local visibility forecasts.