Prahar

Prahar or Prahara is a Sanskrit term for a unit of time, or subdivision of the day, approximately three hours long.

The day is divided into eight parts: four praharas for the day, and four for the night. The first prahara of the day begins at sunrise, and the fourth prahara of the day ends at sunset. A second round of four praharas unfolds during the night, between sunset and sunrise.

The traditional system of praharas overlaps (but does not coincide) with the more precise traditional system of muhurtas, which is based on precise astronomical calculations.

Thus, the day can be regarded as divided into eight praharas (of three hours each) or thirty muhurtas (of 48 minutes each). In both systems, the day commences with sunrise. The timing of the two systems coincides only at sunrise and sunset (four praharas coincide with fifteen muhurtas at the twelve-hour, or 720-minute, point).

In the ancient Puranas we see the day divided into eight praharas: four for the day and four for the night. The concept still prevails today in India, particularly in connection with the performance of Indian classical music (see below).

The first prahara is commonly placed at sunrise, although some sources place it at the brahma-muhurta, a period of time before sunrise (around 4.30 amwhen Venus can be sighted).

The concept of prahar originated where the lengths of the day and night were based on actual, observable sunrise and sunset. The four praharas of the day start at sunrise, and the four praharas of the night at sunset. If the location is near the equator, where day and night are the same length year round, the praharas of the day and the praharas of the night will be of equal length (three hours each). In other regions, where the relative length of day and night varies according to the season, the praharas of the day will be longer or shorter than the praharas of the night.

Contemporary discussions of prahara often use 6:00 am (the time of sunrise at the equator and at the equinoxes) as a theoretical fixed point of reference for mapping out the praharas at three-hour intervals (6-9, 9-12, etc.). This scheme is a useful pedagogical tool and an efficient way of applying the concept of prahara in a technological "clock" culture. However, it's important to realize that this rigid schema most likely does not capture the original application of prahara. In a traditional, non-technological culture, the length of day and night are based on observable sunrise and sunset. The day, which starts at sunrise and ends at sunset, is divided into four praharas of equal length; and, the night, which starts at sunset and ends at sunrise, is also divided into four equal watches. During the summer, when the days are longer than the nights, the praharas of the day will be longer than the praharas of the night, and vice versa during the winter.

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