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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.
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.
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.
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|
|1001||Jan 1 06:15||Jan 9 07:30||Jan 16 09:08|
|1002||Jan 23 7:39||Jan 31 04:10||Feb 7 21:54||Feb 14 17:04|
|1003||Feb 21 22:35||Mar 1 01:22||Mar 8 09:40||Mar 15 01:25|
|1004||Mar 22 14:37||Mar 30 19:41||Apr 6 19:19||Apr 13 10:50|
|1005||Apr 21 07:18||Apr 29 09:58||May 6 03:35||May 12 21:47|
|1006||May 20 23:47||May 28 20:16||Jun 4 11:12||Jun 11 10:41|
|1007||Jun 19 15:02||Jun 27 03:30||Jul 3 18:52||Jul 11 01:48|
|1008||Jul 19 04:24||Jul 26 08:56||Aug 2 03:27||Aug 9 18:55|
|1009||Aug 17 15:54||Aug 24 13:54||Aug 31 13:58||Sep 8 13:15|
|1010||Sep 16 02:11||Sep 22 19:41||Sep 30 03:19||Oct 8 07:33|
|1011||Oct 15 12:02||Oct 22 03:32||Oct 29 19:50||Nov 7 00:36|
|1012||Nov 13 22:08||Nov 20 14:31||Nov 28 14:46||Dec 6 15:32|
|1013||Dec 13 08:42||Dec 20 05:19||Dec 28 10:21|
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.
As the Moon orbits Earth, it changes phase in an orderly way. Follow these links to understand the various phases of the moon.
Full Moon | Full Moon Names | Blue Moon | Wolf Moon | Snow Moon | Worm Moon | Pink Moon | Flower Moon | Strawberry Moon | Buck Moon | Sturgeon Moon | Harvest Moon | Hunters Moon | Beaver Moon | Cold Moon |
Full Moon Calendar | Lunar Calendar | Lunar Eclipse Calendar | Solar Eclipse Calendar | Full Moon Calendar 2011 | Full Moon Calendar 2012 | Full Moon Calendar 2013 | Full Moon Calendar 2014 | Full Moon Calendar 2015 |
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