Moon Phases & Lunar Calendar

The eight moon phases are: New Moon (0% illuminated), Waxing Crescent, First Quarter (50% illuminated and growing), Waxing Gibbous, Full Moon (100% illuminated), Waning Gibbous, Last Quarter (50% illuminated and shrinking), and Waning Crescent. Each complete cycle from one New Moon to the next takes approximately 29.5 days, which is called a synodic month.

A full moon occurs roughly every 29.5 days — the length of one lunar cycle (synodic month). This means there are about 12 to 13 full moons per year. When two full moons occur in the same calendar month, the second is called a Blue Moon. Full moons are named by season or month; for example, the January full moon is called the Wolf Moon.

A supermoon occurs when a full moon (or new moon) coincides with the moon being at or near its closest point to Earth in its elliptical orbit, called perigee. At perigee, the moon can appear up to 14% larger and 30% brighter than when it is at apogee (its farthest point). There is no strict scientific definition of 'supermoon'; the term was coined by astrologer Richard Nolle in 1979.

The scientific evidence is mixed. Some studies have found small associations between the full moon and reduced sleep duration or later sleep onset, while other studies have found no significant effect. The idea that the moon influences human behavior (the 'lunar effect') is widespread in folklore, but large-scale, well-controlled research has not consistently confirmed it.

A lunar eclipse occurs when the Earth passes directly between the Sun and the full Moon, casting Earth's shadow on the Moon and turning it red or brown ('blood moon'). A solar eclipse occurs when the Moon passes between the Earth and the Sun, partially or fully blocking the Sun from view. Lunar eclipses are visible from the entire night-side of Earth, while total solar eclipses are only visible within a narrow path on Earth's surface.