Many Indians conflate this festival with the Winter Solstice, and believe that the sun ends its southward journey (Sanskrit: Dakshinayana) at the Tropic of Capricorn, and starts moving northward (Sanskrit: Uttarayaana) towards the Tropic of Cancer, in the Nepalese Hindu month of Poush on this day in mid-January. While there is no overt solar observance of Winter Solstice in the Indian religion, the Vaikuntha Ekadashi festival, calculated on the lunar calendar, falls the closest. Further, the Sun makes its northward journey on the day after winter solstice when day light increases. Therefore, Makar Sankranti signifies the celebration of the day following the day of winter solstice. Scientifically, currently in the Northern Hemisphere, winter solstice occurs between 21 and 22 December. Day light will begin to increase on 22 December and on this day, the Sun will begin its northward journey which marks Uttarayaan. The date of winter solstice changes gradually due to the Axial precession of the Earth, coming earlier by approximately 1 day in every 70 years. Hence, if the Makara Sankranti at some point of time did mark the day after the actual date of winter solstice, a date in mid-January would correspond to around 300CE, the heyday of Indian mathematics and astronomy.