What are the phases of the moon?

THE PHASES OF THE MOON

The earth makes one full revolution on it axis every 24 hours. The moon takes a month to orbit the earth. During that time, it moves from between the earth and the sun around to the far side of the earth, and back to between the earth and the sun. Each phase appears different to someone viewing the moon from the earth. If you imagine the earth in the center of a clock face, the moon begins its monthly rotation at the three o’clock position and rotates counterclockwise.

Understanding the Moon Phases: A diagram of the orbit pattern, and explanations of the different phases of the moon, tides, and eclipses.

New Moon

At the time of the new moon, the moon is directly between the earth and the sun (the three o’clock position), thus the lit side of the moon is facing away from the earth and it appears there is no moon because we “see” only the dark side. The only time the moon is visible during this phase is during a solar eclipse.

See a picture of a new moon.

Waxing Crescent

As the moon begins to move slowly away from the sun (moving from three o’clock toward twelve o’clock), a small portion of the moon is illuminated in a crescent shape. At first it is just a sliver, and each night the sliver becomes a little larger until it reaches the first quarter.

See a picture of a waxing crescent moon.

First Quarter

When the moon reaches the “first quarter” of its cycle around the earth (twelve o’clock position), the one-half of the moon is illuminated by the sun. This occurs about one week after a new moon.

See a picture of a first quarter moon.

Waxing Gibbous

As the moon passes the northernmost point of its rotation and heads toward the western side of the earth (moving from twelve o’clock toward nine o’clock), more and more of the moon is illuminated. After several days, it reaches the opposite of the waxing crescent: nearly all the moon is lit and just a small crescent is still dark.

See a picture of a waxing gibbous moon.

Full Moon

Once the moon reaches the midpoint in its monthly orbit, it is directly opposite the sun and fully illuminated. At this time, it’s in the nine o’clock position.

See a picture of a full moon.

Waning Gibbous

As the moon rotates to the south (from nine o’clock to six o’clock), it begins to pass lower than the sun and again slowly develops a darkened crescent on one side. It begins as a small sliver and increases over several days until the three-quarter moon.

See a picture of a waning gibbous moon.

Last Quarter

The last quarter of the moon is also known as the third-quarter because it is about to enter the final one-fourth of its monthly orbit. It the last quarter (at six o’clock), the moon is once again half illuminated, but this time it is the side opposite that lit in the first quarter.

See a picture of a last quarter moon.

Waning Crescent

Finally, as the moon moves through its final phase back toward its original position directly between the earth and sun (moving from six o’clock back to three o’clock), it gets increasingly darker until finally there is just a small crescent-shaped sliver of illumination.

See a picture of a waning crescent moon.

The moon orbits the earth once every 29.53 days. A lunar month is the time it takes the moon to go from one new moon to the next. The term waxing means “to increase in phase or intensity,” thus the first half of the lunar month leading to a full moon is the waxing phase. The term waning means “to diminish in phase or intensity,” thus the second half of the lunar month leading to the next new moon is the waning phase.

Since 1999, when there were not one but two extra full moons, one in January and one in March (with no full moon at all in February), blue moon has come to mean the extra, or second full moon in a month. This is not accurate: each season typically has three full moons and when a season has four, the third moon of the four is considered the blue moon.

The word lunacy means “intermittent insanity once believed to be related to phases of the moon.” Although insanity is now known to be the product of brain chemistry and other organic problems, it has been observed and documented that prisoners and hospital patients are more agitated and violent during the full moon. Usually, Emergency Rooms and Police Stations are busier during the full moon, as well.

In folklore, it is believed that humans who are werewolves turn into their wolf form at the full moon. Belief in lycanthropy dates back centuries, and is frequently depicted in books, television, and movies.

Pagan religions celebrate Esbat at the full moon; it is believed that the moon goddess is at the height of her power at that time. In some Chinese religions, ritual offerings to ancestors and deities are made at the full moon.

Lunar Lore: Folklore and theories about the moon’s effect on everything from agriculture to murder.

The moon is beautiful to see in all of its phases; if you understand the subtle differences in how it appears, it can also be a calendar guide.

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