Lunation

The complete cycle of moon phases beginning with the new moon and ending with the next new moon. Lunation has an average duration of 29.5 days.

New Moon

The moon's not visible in the sky. Except during a solar eclipse!

Waxing Crescent

The moon's less than one-half illuminated by the sun but less than one quarter illuminated. The waxing crescent occurs when the moon is illumination is increasing.

First Quarter

The moon's one-half illuminated by the sun. The first quarter occurs when the moon is illumination is increasing.

Waxing Gibbous

The moon's more than one-half illuminated by the sun but not completely illuminated. The waxing gibbous occurs when the moon is illumination is increasing.

Full Moon

The moon's totally visible in the sky. Except during a lunar eclipse!

Waning Gibbous

The moon's more than one-half illuminated by the sun but not completely illuminated. The waning gibbous occurs when the moon is illumination is decreasing.

Last Quarter

The moon's one-half illuminated by the sun. The last quarter occurs when the moon is illumination is decreasing.

Waning Crescent

The moon's less than one-half illuminated by the sun but less than one quarter illuminated. The waning crescent occurs when the moon is illumination is decreasing.