Waning Gibbous Moon

Waning Gibbous Moon Definition

What is a waning gibbous moon? The waning gibbous moon, is defined to occur when the Moon appears to be more than one-half but not fully illuminated by direct sunlight. Because the fraction of the Moon’s disk that is illuminated is decreasing, we consider the Moon to be “waning.” Each new lunar cycle is measured beginning at each new moon and the waning gibbous moon occurs when the Moon is more than one-half but less than three-fourths of the way around the sky (i.e., along its orbit) from new moon.

Waning Gibbous Moon Dates / Next Waning Gibbous Moon

When is the next waning gibbous moon? A waning gibbous moon a little more than two weeks after a new moon. The average calendrical month, which is 1/12 of a year, is about 30.44 days, while the Moon’s phase (synodic) cycle repeats on average every 29.53 days. Therefore the timing of the Moon’s phases shifts by an average of almost one day for each successive month. To find out the waning gibbous moon dates, please see the waning gibbous moon calendar below.

Waning Gibbous Moon and The Moon Phases

Waning Gibbous Moon

Waning Gibbous Moon

The waning gibbous moon happens when the moon is between a 90 and 135 degree angle with respect to the Earth and Sun. So we are seeing more than half of the moon illuminated and less than half in shadow. The word gibbous refers to phases where the moon is more than half illuminated. “Waning” essentially means shrinking or decreasing in illumination. Each evening, as the moon’s orbital motion carries it away from the Earth-Sun line, we see less of the moon’s day side.



Waning Crescent Moon Calendar 2012

The waning crescent moon calendar for 2012 is expressed in Coordinated Universal Time (UT), the international basis for other time zones, and occurs on the days between each full moon and last quarter moon. On these days, a waning gibbous moon sails over the eastern horizon in the hours between sunset and midnight. Astronomers call one lunar cycle a lunation. For waning gibbous moon times in your city, please use the Time Zone Converter.

Lunation New Moon First Quarter Full Moon Last Quarter

Gibbous Moon


Moon Phases, Full Moons and Moon Calendars


Full Moons


Moon Phases


Moon Calendars


Eclipses & Moon Facts
