Makar Sankranti or Uttarayan or Maghi or simply Sankranti, is a festival day in the Hindu calendar, dedicated to the deity Surya (sun). It is observed each year the day Sun enters the Capricorn zodiac which corresponds with the month of January as per the Gregorian calendar. It marks the first day of the sun’s transit into Makara rashi (Capricorn), marking the end of the month with the winter solstice and the start of longer days.
Makar Sankranti is one of the few ancient Indian festivals that has been observed according to solar cycles, while most festivals are set by the lunar cycle of the lunisolar (चंद्र – सौर) Hindu calendar. Being a festival that celebrates the solar cycle, it almost always falls on the same Gregorian date every year (January 14), except in some years when the date shifts by a day for that year (January 15). As a result, it can fall on different date of the Hindu calendar each year.