First Quarter Moon PhaseW
hat is a first quarter moon
? The first quarter moon
, sometimes known as 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 90 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 increasing. Each new lunar cycle is measured beginning at each new moon
and the first quarter moon
occurs when the Moon is one-quarter of the way around the sky (i.e., along its orbit) from new moon.
First Quarter Moon Dates / Next First Quarter Moon
When is the next first quarter moon? A first quarter moon comes a week after 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 first quarter moon calendar below.
First Quarter Moon and The Moon Phases
First Quarter Moon
The first quarter moon (often called a “half 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.
First Quarter Moon Calendar 2019
The first quarter moon calendar for 2019 is expressed in Coordinated Universal Time (UT), the international basis for other time zones. A first quarter moon rises at noon and is high overhead at sunset. It sets around midnight. Astronomers call one lunar cycle a lunation. For first 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.
Popular Full Moon Calendars
Some popular full moon calendars, in addition to the First Quarter 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.
You can also check out our Full Moon Calendar, Lunar Calendar, Lunar Eclipse Calendar and Solar Eclipse Calendar!