Last Quarter Moon Phase

What is a last quarter moon? The last quarter moon, sometimes known as the third quarter moon or a half moon, is defined to occur when the excess of the apparent ecliptic (celestial) longitude of the Moon over that of the Sun is 270 degrees. This means that one-half of the Moon appears to be illuminated by direct sunlight and the fraction of the Moon’s disk that is illuminated is decreasing. Each new lunar cycle is measured beginning at each new moon and the last quarter moon occurs when the Moon is three-quarters of the way around the sky (i.e., along its orbit) from new moon.

Last Quarter Moon Dates / Next Last Quarter Moon

When is the next last quarter moon or third quarter moon? A last quarter moon comes about three 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 first quarter moon dates, please see the last quarter moon calendar below.

Last Quarter Moon and The Moon Phases

The last quarter moon (often called a “half moon” or the “third quarter moon”), happens when the moon is at a 90 degree angle with respect to the Earth and Sun. So we are seeing exactly half of the moon illuminated and half in shadow.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.

Last Quarter Moon Calendar 2020

The last quarter moon calendar for 2020 is expressed in Coordinated Universal Time (UT), the international basis for other time zones. Astronomers call one lunar cycle a lunation. For last quarter 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.