Moon & lunar calculators

Astronomy-based moon tools: phase name and illumination for any date, countdown to the next full or new moon, days since the last new moon, and approximate moonrise/moonset from latitude and longitude. Cite USNO references — factual sky math, not horoscope text.

Unlike our astrology section, these are astronomical calculations. The lunar cycle from one new moon to the next averages about 29.53 days, but individual cycles vary by several hours because the Moon’s orbit is elliptical and both it and the Earth are being tugged by the Sun. Phase is effectively global — the Moon shows nearly the same illuminated fraction to everyone at a given moment — while rise and set times are strongly local and shift by roughly 50 minutes each day. Our rise and set figures are approximations that ignore terrain, atmospheric refraction near the horizon, and your elevation, so treat them as a guide for planning rather than a precise almanac. Phase names mark points in a continuous cycle: the Moon is exactly full for an instant, though it looks full for a couple of nights either side.