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The Moon then wanes as it passes through the gibbous moon, third-quarter moon, and crescent moon phases, before returning back to new moon. The terms old moon and new moon are not interchangeable. The "old moon" is a waning sliver (which eventually becomes undetectable to the naked eye) until the moment it aligns with the Sun and begins to wax ...
A lunar calendar is a calendar based on the monthly cycles of the Moon's phases (synodic months, lunations), in contrast to solar calendars, whose annual cycles are based on the solar year. The most widely observed purely lunar calendar is the Islamic calendar .
The term lunar month usually refers to the synodic month because it is the cycle of the visible phases of the Moon. Most of the following types of lunar month, except the distinction between the sidereal and tropical months, were first recognized in Babylonian lunar astronomy .
The lunar standstill phenomenon was probably known from Megalithic times. In high latitudes, there was a period within the 18.6 years cycle, when the Moon became circumpolar. [4] It would have drawn the attention of locals. In other latitudes, the major lunar standstill featured constant scene illumination during the full Moon.
A lunar day is the time it takes for Earth's Moon to complete on its axis one synodic rotation, meaning with respect to the Sun. Informally, a lunar day and a lunar night is each approx. 14 Earth days. The formal lunar day is therefore the time of a full lunar day-night cycle.
The Lunation Number or Lunation Cycle is a number given to each lunation beginning from a specific one in history. Several conventions are in use. The most commonly used was the Brown Lunation Number (BLN), which defines "lunation 1" as beginning at the first new moon of 1923, the year when Ernest William Brown's lunar theory was introduced in the American Ephemeris and Nautical Almanac.
Lunar New Year is the beginning of a new year based on lunar calendars or, informally but more widely, lunisolar calendars. Lunar calendars follow the lunar phase while lunisolar calendars follow both the lunar phase and the time of the solar year. The event is celebrated by numerous cultures in various ways at diverse dates.
The (19-year) Metonic cycle is a lunisolar cycle, as is the (76-year) Callippic cycle. [8] An important example of an application of the Metonic cycle in the Julian calendar is the 19-year lunar cycle insofar as provided with a Metonic structure. [9] Meton introduced the 19 year cycle to the Attic calendar in 432 BC.