Ayurveda In
Ayurveda, the period of Uttarayana is associated with seasonal changes believed to influence human health and bodily balance. Ayurvedic texts describe this six-month period as
Adana Kala ("the time of taking away"), referring to the belief that the Sun's increasing intensity gradually draws moisture and strength from living beings and the environment. During this period, the cooling and nourishing qualities of the earth are believed to diminish as solar heat increases. Classical Ayurvedic literature on "
Ritucharya" states that
tikta (bitter),
kashaya (astringent), and
katu (pungent) rasas (tastes) become more dominant in nature during this time. These qualities contribute to dryness in the body and a gradual reduction in
bala (physical strength or vitality).
Surya Siddhanta Mayasura, the composer of
Surya Siddhanta, defines
Uttarayana, at the time of composition, as the period between the
Makara Sankranti (which currently occurs around January 14) and
Karka Sankranti (which currently occurs around July 16). Lātadeva describes this as half revolutions of the Sun, using the terms Uttarayana and Dakshinayana to describe the "northern and southern progress" respectively. Bal Gangadhar Tilak, a scholar and mathematician, proposes an alternative, early vedic definition of Uttarayana as starting from Vernal Equinox and ending with Autumnal Equinox. This definition interprets the term "Uttara Ayana" as "northern movement" instead of "northward movement", i.e. as the movement of the Earth in the region North of the Equator. In support of this proposal, he points to another tradition that the Uttarayana is considered the daytime of the Gods residing at the North Pole which tradition makes sense only if we define Uttarayana as the period between the Vernal and Autumnal equinoxes (when there is
Midnight Sun at the North Pole). Conversely, Dakshinaya is defined as the period between the Autumnal and Vernal Equinoxes, when there is midnight sun at the South Pole. This period is also referred to as Pitrayana (with the Pitrus (i.e. ancestors) being placed at the South Pole).
Drik Siddhanta This festival is currently celebrated on the 14th or 15 January but due to
axial precession of the Earth it will continue to shift away from the actual season. The season occurs based on tropical sun (without ayanamsha). The Earth revolves around Sun with a tilt of 23.44 degrees. When the tilt is facing the Sun it is defined as summer and when the tilt is away from the Sun it is called winter. That is the reason when there is summer north of the equator, it will be winter south of the equator. Because of this tilt, the Sun appears to travel north and south of the equator. This motion of the Sun transitioning from south to north is called Uttarayana (the Sun is moving towards north). Once the Sun reaches north, it begins moving south and is called Dakshinayana – the Sun is moving towards south. This causes seasons which are dependent on equinoxes and solstices. == Religious significance ==