Moon Phases Explained

Over the course of the month, the Moon displays different phases. (See our Moon Phase Calendar below.) There are eight distinct phases that appear (and repeat in a cycle) in the following order:

1. New (usually invisible)
2. Waxing Crescent (pictured below)
3. First Quarter (the right half is illuminated)
4. Waxing Gibbous
5. Full (See full Moon times here.)
6. Waning Gibbous
7. Last Quarter (the left half is illuminated)
8. Waning Crescent

See these phases illustrated in a diagram here.

What causes the different Moon phases? No, the Moon doesn’t change its shape! The answer is light. The Moon generates no light of its own. It reflects the Sun’s light like a gigantic mirror. (Fun fact: Light travels 93 million miles from the Sun, bounces off the surface of the Moon, and then travels another 240,000 miles to reach your eyes.) The phase you see depends on where the Moon is in its orbit around Earth.

When the Moon is between the Sun and Earth, it is usually not seen. This is called a “New Moon.” After a day or so, the Moon begins to pass the Sun in its orbit around the Earth. As it does, its right side becomes a crescent Moon. See the photo below:

The Moon continues to travel eastward in its orbit and reflect more of the Sun’s light. As it does, its right side glows brighter.

When the Moon has made one fourth (or one quarter) of its trip around the Earth, it reaches its First Quarter phase. At this time, the Moon, and Earth form a right angle. From this point, the Moon’s brightness continues to grow through the waxing gibbous phase until it becomes a full Moon. Full Moons occur when the Moon is at the exact opposite side of the Earth as the Sun.

See full Moon dates and times here.

After the full Moon, the Moon is considered to be waning (diminishing in light). The Moon phases continue in reverse order, beginning with gibbous and ending with crescent. Then the cycle repeats again with the next New Moon.

The Moon is always illuminated from right to left over the course of the month. So if you happen to see a crescent on the right side, you know the Moon is waxing (heading towards a full Moon) and if you see a crescent on the left side, the Moon is waning (heading towards a New Moon phase).

The information above was provided by Dean Regas, Astronomer for the Cincinnati Observatory.

Moon Phase Calendar From The Farmers’ Almanac

The calendar below is a general guide for the Moon phases over the course of the current month.

This information is helpful for observing the Moon and stars according to our Monthly Night Sky Guides!

Note: On occasion, you will see a full Moon listed on two days. This is usually due to the Moon reaching peak illumination between the end of one day and the beginning of the next. Peak illumination sometimes occurs during daylight hours. If you would like to learn more about each of the full Moons throughout the course of the year, visit our Full Moon Dates And Times Page.

In some cases, moonrise and other times may be missing because they do not apply. For example, the Moon may not rise and set every day (particularly in higher latitudes). In addition, while the Sun always sets after the Sun rises on the same day, the Moon may set in the morning and rise in the afternoon as the Moon’s orbit is not based on the Earth day.

Learn more about the next full Moon.

Join The Discussion

What are your favorite Moon phases?

Do you prefer a crescent Moon or a full Moon?

Have you used our Moon Phase Calendar to plan any activities?

Share with your community here in the comments below!