 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 Maghe 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 English mathematics and astronomy.