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http://en.wikipedia....isolar_calendar
A lunisolar calendar is a calendar in many cultures whose date indicates both the moon phase and the time of the solar year. If the solar year is defined as a tropical year then a lunisolar calendar will give an indication of the season; if it is taken as a sidereal year then the calendar will predict the constellation near which the full moon may occur. The Hebrew, Buddhist, Hellenic, Hindu lunisolar, Burmese, Tibetan, Chinese, Vietnamese, Mongolian, and Korean calendars are all lunisolar.
http://en.wikipedia....Hebrew_calendar
The Hebrew calendar (הלוח העברי ha'luach ha'ivri), or Jewish calendar, is a lunisolar calendar used today predominantly for Jewish religious observances. It determines the dates for Jewish holidays and the appropriate public reading of Torah portions, yahrzeits (dates to commemorate the death of a relative), and daily Psalm reading, among many ceremonial uses. In Israel, it is an official calendar for civil purposes and provides a time frame for agriculture.
Because of the roughly eleven-day difference between twelve lunar months and one solar year, the length of the Hebrew calendar year varies in a repeating 19-year Metonic cycle of 235 lunar months, with an intercalary lunar month added according to defined rules every two or three years, for a total of 7 times per 19 years. Seasonal references in the Hebrew calendar reflect its development in the region east of the Mediterranean and the times and climate of the Northern Hemisphere. The Hebrew calendar year is longer by about 6 minutes and 25+25/57 seconds than the present-day mean solar year, so that every 224 years, the Hebrew calendar will fall a full day behind the modern solar year, and about every 231 years it will fall a full day behind the Gregorian calendar year.
http://en.wikipedia....i/Metonic_cycle
In astronomy and calendar studies, the Metonic cycle or Enneadecaeteris (from Greek words for nineteen years) is a period of very close to 19 years which is remarkable for being very nearly a common multiple of the tropical year and the synodic (lunar) month. The Greek astronomer Meton of Athens observed that a period of 19 tropical years is almost exactly equal to 235 synodic months, and rounded to full days counts 6940 days. The difference between the two periods (of 19 tropical years and 235 synodic months) is only 2 hours ... To keep a 12-month lunar year in pace with the solar year, an intercalary 13th month would have to be added on seven occasions during the nineteen-year period. Meton introduced a formula for intercalation in circa 432 BC ... Traditionally (in the ancient Attic and Babylonian lunisolar calendars, as well as in the Hebrew calendar), the years 3, 6, 8, 11, 14, 17, and 19 are the long (13-month) years of the Metonic cycle. This cycle can be used to predict eclipses, forms the basis of the Greek and Hebrew calendars ... The Chaldean astronomer Kidinnu (4th century BC) knew of the 19-year cycle, but the Babylonians may have learned of it earlier. They measured the moon's motion against the stars, so the 235:19 relation may originally have referred to sidereal years, instead of tropical years as it has been used in various calendars ... The Runic calendar is a perpetual calendar based on the 19-year-long Metonic cycle. Also known as a Rune staff or Runic Almanac, it appears to have been a medieval Swedish invention. The calendar does not rely on knowledge of the length of the tropical year or of the occurrence of leap years. It is set at the beginning of each year by observing the first full moon after the winter solstice.
http://en.wikipedia.org/wiki/Saros_cycle
The saros is an eclipse cycle with a period of 223 synodic months (approximately 6585.3213 days, or nearly 18 years 11 1/3 days), that can be used to predict eclipses of the Sun and Moon. One saros after an eclipse, the Sun, Earth, and Moon return to approximately the same relative geometry, and a nearly identical eclipse will occur. The earliest discovered historical record of the saros is by the Chaldeans (ancient Babylonian astronomers) in the last several centuries BC, and was later known to Hipparchus, Pliny and Ptolemy, but under different names. The Sumerian/Babylonian word "šár" was one of the ancient Mesopotamian units of measurement and as a number appears to have had a value of 3600
A lunisolar calendar is a calendar in many cultures whose date indicates both the moon phase and the time of the solar year. If the solar year is defined as a tropical year then a lunisolar calendar will give an indication of the season; if it is taken as a sidereal year then the calendar will predict the constellation near which the full moon may occur. The Hebrew, Buddhist, Hellenic, Hindu lunisolar, Burmese, Tibetan, Chinese, Vietnamese, Mongolian, and Korean calendars are all lunisolar.
http://en.wikipedia....Hebrew_calendar
The Hebrew calendar (הלוח העברי ha'luach ha'ivri), or Jewish calendar, is a lunisolar calendar used today predominantly for Jewish religious observances. It determines the dates for Jewish holidays and the appropriate public reading of Torah portions, yahrzeits (dates to commemorate the death of a relative), and daily Psalm reading, among many ceremonial uses. In Israel, it is an official calendar for civil purposes and provides a time frame for agriculture.
Because of the roughly eleven-day difference between twelve lunar months and one solar year, the length of the Hebrew calendar year varies in a repeating 19-year Metonic cycle of 235 lunar months, with an intercalary lunar month added according to defined rules every two or three years, for a total of 7 times per 19 years. Seasonal references in the Hebrew calendar reflect its development in the region east of the Mediterranean and the times and climate of the Northern Hemisphere. The Hebrew calendar year is longer by about 6 minutes and 25+25/57 seconds than the present-day mean solar year, so that every 224 years, the Hebrew calendar will fall a full day behind the modern solar year, and about every 231 years it will fall a full day behind the Gregorian calendar year.
http://en.wikipedia....i/Metonic_cycle
In astronomy and calendar studies, the Metonic cycle or Enneadecaeteris (from Greek words for nineteen years) is a period of very close to 19 years which is remarkable for being very nearly a common multiple of the tropical year and the synodic (lunar) month. The Greek astronomer Meton of Athens observed that a period of 19 tropical years is almost exactly equal to 235 synodic months, and rounded to full days counts 6940 days. The difference between the two periods (of 19 tropical years and 235 synodic months) is only 2 hours ... To keep a 12-month lunar year in pace with the solar year, an intercalary 13th month would have to be added on seven occasions during the nineteen-year period. Meton introduced a formula for intercalation in circa 432 BC ... Traditionally (in the ancient Attic and Babylonian lunisolar calendars, as well as in the Hebrew calendar), the years 3, 6, 8, 11, 14, 17, and 19 are the long (13-month) years of the Metonic cycle. This cycle can be used to predict eclipses, forms the basis of the Greek and Hebrew calendars ... The Chaldean astronomer Kidinnu (4th century BC) knew of the 19-year cycle, but the Babylonians may have learned of it earlier. They measured the moon's motion against the stars, so the 235:19 relation may originally have referred to sidereal years, instead of tropical years as it has been used in various calendars ... The Runic calendar is a perpetual calendar based on the 19-year-long Metonic cycle. Also known as a Rune staff or Runic Almanac, it appears to have been a medieval Swedish invention. The calendar does not rely on knowledge of the length of the tropical year or of the occurrence of leap years. It is set at the beginning of each year by observing the first full moon after the winter solstice.
http://en.wikipedia.org/wiki/Saros_cycle
The saros is an eclipse cycle with a period of 223 synodic months (approximately 6585.3213 days, or nearly 18 years 11 1/3 days), that can be used to predict eclipses of the Sun and Moon. One saros after an eclipse, the Sun, Earth, and Moon return to approximately the same relative geometry, and a nearly identical eclipse will occur. The earliest discovered historical record of the saros is by the Chaldeans (ancient Babylonian astronomers) in the last several centuries BC, and was later known to Hipparchus, Pliny and Ptolemy, but under different names. The Sumerian/Babylonian word "šár" was one of the ancient Mesopotamian units of measurement and as a number appears to have had a value of 3600