The Full Moon
The Full Moon is the most spectacular Moon phase when the entire face of the Moon is lit up.
At Full Moon, the entire face of the Moon is illuminated by the Sun's rays and it can be bright enough to light up otherwise dark nights.
Technically, this primary Moon phase only lasts a moment, the instant when the Sun and the Moon are aligned on opposite sides of Earth (see illustration). So the exact time for Full Moon is during the day on parts of the planet.
However, the Moon can appear to be full a day before or after while more than 98% of the Moon's disc is illuminated.
Earth in the Middle
The technical term for the Full Moon alignment is syzygy of the Sun-Earth-Moon-system.
When the side of the Moon we can see from Earth is fully lit up at Full Moon, the opposite side is in darkness, and vice versa at New Moon.
A Primary Moon Phase
In addition, there are four intermediate phases which take up the time in between the primary phases. These are called Waxing Crescent Moon, Waxing Gibbous Moon, Waning Gibbous Moon, and Waning Crescent Moon.
The Moon orbits Earth counterclockwise on an elliptical path, and the same side of the Moon always faces Earth. However, over time, the Moon rocks slightly from north to south and wobbles a little from east to west. This motion, known as lunar libration, makes it possible to see up to 58% of the Moon’s surface from Earth, although only 50% at a time.
Supermoon and Micromoon
The point of the Moon's orbit closest to Earth is called perigee and the point farthest away is known as apogee. When the Full Moon comes close to the perigee, it is known as a Supermoon or Super Full Moon.
Higher Tides at Full Moon
The greatest difference between high and low tide is around Full Moon and New Moon. During these Moon phases, the gravitational forces of the Moon and the Sun combine to pull the ocean’s water in the same direction. These tides are known as spring tides or king tides.
Causes Lunar Eclipses
Around 2 or 3 times a year, the Full Moon comes close to the lunar nodes. These are the points where the Moon's orbit crosses the ecliptic, which is the path of the Sun, seen from Earth. When this happens, Earth cast its shadow on the Full Moon, causing a lunar eclipse.
Solar eclipses, on the other hand, can only happen if the Moon comes close to the lunar nodes around New Moon.
Blue Moon Is a Full Moon
Most years have 12 Full Moons, 1 each month. However, our calendar is not perfectly synchronized with astronomical events. Therefore, every now and then, a year has 13 Full Moons. When this happens, at least one of those Full Moons is called a Blue Moon.
Full Moon in Calendars
The symbol for Full Moon in modern calendars is a completely white circle.
The other primary Moon phase symbols in calendars are:
= New Moon, = First Quarter, = Third Quarter
Affects the Tides
The tides on Earth are mostly generated by the Moon’s gravitational pull from one side of Earth to the other. The Moon’s gravity can cause small ebbs and flows in the continents called land tides or solid Earth tides. These are greatest during the Full and New Moons because the Sun and Moon are aligned on the same or opposite sides of Earth.
The Full Moon in Culture
The Moon has also inspired the invention of countless deities, like the Roman goddess Luna or her Norse male counterpart Máni, who gave his name to Monday. And, even today, people use ancient Full Moon names, like Harvest Moon and Strawberry Moon.
Witches and Werewolves
In the past, it was common to think that many forms of mental illness were caused by the Moon, hence the name lunatic. The Full Moon has even been held responsible for supernatural transformations, changing otherwise harmless men into ferocious werewolves.
Modern Full Moon Celebration
The Full Moon still inspires celebrations. One of the most famous gatherings these days is the monthly Full Moon party on Haad Rin beach on the island of Koh Pha Ngan, Thailand, where thousands of tourists gather every month.