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Full Moon: Dates, Meaning & Science
A Full Moon is the luminous midpoint of the lunar cycle—an alignment we can calculate precisely and a sight cultures have interpreted in many different ways.
What is a Full Moon?
A Full Moon occurs when the Moon’s geocentric ecliptic longitude is 180° from the Sun. Its Earth-facing hemisphere is almost entirely sunlit. Perfect 100% illumination is uncommon in casual displays because the geometry changes continuously and a lunar eclipse can dim the Moon near exact opposition.
How often does it happen?
Successive Full Moons are separated by about 29.53 days, the mean synodic month. Calendar months are longer, so a month occasionally contains two Full Moons. The exact interval varies slightly because the lunar orbit is elliptical and perturbed by the Sun.
Cultural and spiritual meaning
In folklore, astrology, and modern spiritual practice, Full Moons are often associated with culmination, heightened awareness, or release. These are traditions and interpretations; astronomy does not establish that the phase causes human behavior, health changes, or outcomes.
Questions, answered
Frequently asked questions
Is the Full Moon visible all night?
Near the Full Moon, it rises around sunset and sets around sunrise, though exact times depend on location.
Does a Full Moon cause an eclipse?
No. The Moon’s orbit is tilted, so it usually passes above or below Earth’s shadow.
How long does a Full Moon last?
The exact phase is an instant, while the Moon can look full to the eye for roughly a day on either side.