On the day of Sankranti it is said that the Lord Sun (Surya) visits his son Shani. It is said that generally the two do not get along well but not this day, the Sun visits his son forgetting all differences of opinion.
Hence, Makar Sankranti is considered to be a day to forget sourness and bitter relationships. One must forget all the bitterness or ill-feelings and talk sweetly with everybody.
On this day, people take a dip in the holy Ganga and offer water to the Surya (Sun God).