The six months of the solar year during which the sun is thought to be travelling northward are known as the Solstice.
This would be the time between the winter and summer
solstices (approximately December 20 and June 20) in the common era, and it
would be based on the actual motion of the sun with regard to the earth.
The Indian solar year is calculated differently from Western
astrology and is based on the path of the sun across the zodiac.
The uttarayana starts on Makara Sankranti (the day the sun
enters Capricorn, which is generally January 14) and concludes the day before
Karka Sankranti (the day the sun enters Cancer, usually calculated as July 14).
Because the guardian god for the southern direction is Yama,
who is death personified, the Uttarayana is considered a more fortunate period
than the Dakshinayana (when the sun is traveling toward the south).
