Uttarayana or Uttarayan is six-month period between Makar Sankranti and Kark Sankranti (around July 14) when the sun is moving north on the celestial sphere. Uttarayana name comes from joining two Sanskrit words "Uttara" (North) and "Ayana" (movement against). The period from July 14 to January 14 is known, Dakshinayana. The starting point for Uttarayana celebrated as Makara Sankranti throughout India.
This festival is celebrated on 14 January or 15 January. The season is based on the tropical sun (without ayanamsha). Earth orbits the Sun with an inclination of 23.45 degrees. When the tilt, the sun's summer and when the tilt is away from the sun we get in winter. That is why when it is summer north of the equator, it will be winter south of the equator.
