01What Sankranti is
A Sankranti is the moment the Sun passes from one rashi into the next. There are twelve in a year, roughly a month apart, and each is named for the sign the Sun enters: Mesh Sankranti, Vrishabh Sankranti and on through Meen. Unlike most days on this calendar, a Sankranti is solar, not lunar, so it falls on nearly the same Gregorian date each year. The tradition counts four as especially significant: Makar and Kark, which open the northward and southward halves of the solar year, and Mesh and Tula, the Vishuva Sankrantis that begin the solar year and its second half.
02How the day and time are worked out
This page works out each Sankranti as the moment the Sun enters a sidereal rashi, measured with the Lahiri ayanamsha, and shows that moment beside the day. When the ingress happens by day, the Sankranti is kept that day. When it happens at night, the page follows the classical rule the panchangs apply: Makar Sankranti moves to the next day, Kark Sankranti stays on the day just ending, and every other Sankranti stays if the Sun moves in during the first half of the night and moves to the next day if it moves in during the second half. Bathing and charity belong to the kept day.
03How it is kept
The tradition marks every Sankranti with snan and daan: a bath at dawn, in a river where one can be reached, and charity given the same day, often grain, til, jaggery, clothes or a lamp. The hours around the ingress are called punya kaal and are held to be the fitting time for both. Many offer water to the Sun at sunrise with the Gayatri mantra or the Aditya Hridaya. Each Sankranti also has its own regional face: Makar Sankranti is a major festival across India, and Mesh Sankranti is the solar new year in Tamil Nadu, Kerala, Punjab, Bengal and Assam under different names.
04The rest of the calendar
