Waning Gibbous Moon Phase

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

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.Each lunar cycle begins with a new moon. As the Moon moves eastward away from the Sun in the sky, we see a bit more of the sunlit side of the Moon each night. We call this waxing. After the new moon, the sunlit portion is increasing, but less than half illuminated, so it is a waxing crescent moon. When half of the Moon’s disc is illuminated, we call it the first quarter moon. As the sunlit portion continues to increase, now more than half illuminated, it becomes waxing gibbous moon. When the Moon reaches maximum illumination, a full moon, the Moon has completed one half of the lunar month.During the second half of the lunar month, the Moon grows thinner each night. We call this waning. The waning gibbous moon phase occurs first, followed by the last quarter moon when half of the Moon’s disc is illuminated. Next is the waning crescent moon, which wanes until the illumination is completely gone; a new moon.

Waning Crescent Moon Calendar 2020

The waning crescent moon calendar for 2020 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. You may also simply subtract five (5) hours to get to U.S. Eastern Time.

Gibbous Moon

Any moon that appears more than half lighted but less than full is called a gibbous moon. The word gibbous comes from a root word that means hump-backed. You can see the hump-backed shape of the waning gibbous moon.

Popular Full Moon Calendars

Some popular full moon calendars, in addition to the 2025 Full Moon Calendar, include the following: Moon Calendar 2011,Moon Calendar 2012, Moon Calendar 2013, Moon Calendar 2014, Moon Calendar 2015, Moon Calendar 2016, Moon Calendar 2017, Moon Calendar 2018, Moon Calendar 2019, Moon Calendar 2020, Moon Calendar 2021, Moon Calendar 2022, Moon Calendar 2020, Moon Calendar 2023, Moon Calendar 2024, Moon Calendar 2025.
You can also check out our Full Moon Calendar, Lunar Calendar, Lunar Eclipse Calendar and Solar Eclipse Calendar!

Full Moon Names History