Hindu Lunisolar Calendar

• Report rights infringement
• published: 19 Jan 2013
• views: 5106

This animation illustrates the Hindu lunisolar calendar and its relationship to planetary motion. As the Sun and the Moon orbit the Earth (in a geocentric model), the lunisolar calendar keeps ticking, displaying the appropriate Rashi, Masa, Paksha and Tithi. The following are easily observable: When the moon is in conjunction with the sun, that is a new moon. When the moon is in opposition to the sun, that is a full moon. The Solar Calendar: * A solar year (Sauramana Varsha) is the time taken by the Sun to traverse the entire zodiac. It is assumed that the Vernal Equinox coincides with the beginning of the Hindu Zodiac. * A solar year is divided into two equal Ayanas - Uttarayana and Dakshinayana, being the northward and southward movement of the Sun respectively. Uttarayana begins with the Winter Solstice and Dakshinayana with the Summer Solstice. * Each Ayana is divided into three seasons (Ruthus) resulting in six seasons: Shishira (Winter), Vasantha (Spring), Grishma (Summer), Varsha (Monsoon), Sharath (Fall), Hemanta (Winter again). Shishira begins with the winter solstice the others following in order. Each season comprises of two solar months. (There is a tradition of defining seasons using the lunar calendar, but that is obviously erroneous). * A solar month (Sauramana Masa or Rashi) is the time taken by the Sun to traverse one segment of the zodiac. The moment when the Sun crosses a zodiac sign boundary is called a Sankramana or Sankranthi. Mesha is designated the first solar month. * A solar day (Savana Dina) is from sunrise to sunrise (not modeled here). * The assumption that the Hindu zodiac begins with the Vernal Equinox is no longer accurate. Due to the Precession of the Equinoxes, the starting point of the Hindu zodiac is approx. 24 degrees behind the vernal equinox. Hence all Sauramana definitions which depend on the equinoxes and solstices (i.e. Ayana and Ruthu) are late by 24 days. The Lunar Calendar: * A lunar month (Chandramana Masa) is from new moon to the next new moon. Twelve (and sometime thirteen) lunar months make a lunar year (Chandramana Varsha). * A lunar month is divided into two fortnights (Paksha). A new moon begins Shukla Paksha, i.e. the fortnight of the waxing moon. A full moon begins Krishna Paksha, i.e. the fortnight of the wanning moon. * Each Paksha is constituted of 15 lunar days (Tithis). A Tithi is defined by a 12 degree synodic movement of the moon (i.e. wrt to Earth- Sun axis which itself is moving because of the Sun's movement). The fifteen Tithis of a Paksha are referred to as Prathama, Dwitiya, Tritiya etc. upto Chaturdashi (which simply means First, Second, Third etc. up to Fourteenth in Sanskrit). The fifteenth days is Paurnami (Full Moon) or Amavasya (New Moon). * Every Masa witnesses one Sankramana. Chaitra witnesses a Mesha Sankramana and so on. This is the key link between the solar and lunar parts of the Hindu lunisolar calendar. * A lunar year (of 12 Masas) falls short of a solar year by 11 tithis resulting in the lunar calendar falling out of sync with the solar calendar. This eventually results in a Masa which does not witness a Sankramana. Such a Masa is declared an Adhika Masa i.e. "extra" month. For instance, in the above video, Bhadrapada Masa repeats twice in Year 2; the first of these is the intercalary month (Adhika Bhadrapada) and is entirely within Simha rashi without witnessing any Sankramana; the second is the "NIja" Bhadrapada witnessing a Kanya Sankramana. This resyncronizes the lunar calendar with the solar calendar. The Lunisolar Calendar: * A lunisolar calendar superimposes the lunar calendar on the solar calendar (which in turn is superimposed on the Gregorian calendar). * Some Tithis fall entirely within a solar day and hence are not marked on the lunisolar calendar. * Some Tithis extend over two solar days and hence are repeated twice in succession. An interactive version of this model is available at: http://geogebratube.org/student/m21477