The term Ayana refers to the movement of the sun throughout its annual cycle, which is split according to the direction of the sun's movement in the Hindu calendar.
The uttarayana is the six-month period during which the sun travels northward, and the dakshinayana is the six-month period during which it moves southward.
- The transition points for the sun's direction shift do not fall on the solstices as they are marked on the Gregorian calendar, but approximately three weeks later on Makara Sankranti (about January 14) and Karka Sankranti (around January 21).
- Although many other variables may affect a day's judgment, the sun's northward trip is regarded more auspicious than the sun's southbound travel.
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