How the Moon calendar works
Phase events are recorded as UTC instants and shown in the selected IANA time zone. The UK default is Europe/London, including its daylight-saving transitions.
Daily calendar values
Each daily row is sampled at 12:00 local time. Local noon is documented because a continuously changing phase has no single value for an entire civil day. Phase names come from eight 45-degree sections of the geocentric Moon–Sun ecliptic longitude cycle.
Principal phase events
New Moon, first quarter, full Moon and last quarter use calculated event instants rather than the daily noon sample. The event keeps its UTC instant, then receives a local date and time for the selected zone.
Illumination, lunar age and rounding
Illumination is the calculated fraction of the lunar disc lit from the observer's geocentric perspective. Lunar age is elapsed time since the previous calculated new Moon. Displayed percentages, angles and ages are rounded for readability.
Moonrise, moonset and UK locations
Rise and set are top-limb horizon crossings calculated separately inside the actual Europe/London civil day, so 23-hour and 25-hour clock-change dates retain the correct boundary. Monthly tables use central London. UK comparisons use 18 named locations across England, Scotland, Wales and Northern Ireland at zero modelled elevation.
Eclipse visibility
Eclipse type and global maximum describe the worldwide event. Solar visibility is recalculated for each modelled UK observer, including local maximum and obscuration. Lunar visibility tests the Moon's apparent altitude throughout the global contact span. “UK-visible” means that at least one of the 18 listed locations has part of the event above its astronomical horizon; buildings, terrain and weather are outside the model.
Named and special full Moons
Brown lunation numbers count new-Moon cycles from lunation 1 on 17 January 1923. Blue Moon means the second full Moon in a Europe/London calendar month. Harvest Moon is the full Moon nearest the September equinox, and Hunter's Moon is the next full Moon. Supermoon is marked here when direct geocentric distance at full phase is at most 361,400 km.