Makar Sankranti has an auspicious day ity has an Astrological Significant as the Sun enters the Capricorn (makar) zodian constellation on that day this period is called Uttarayan in Vedic terms. Ultra means North direction Ayan means Movement Uttarayan of sun the remaining 6 month are termed as dakshinayan which means South movement of sun.
From Uttarayan starts the day of devtas, while dakshinayan is said to be the night of devtas, so most of the auspicious things are done during this time
The Vedas say that on this day sun visit the house of his son (Shani), Shani is the Swami of makar Rashi.
On this day, God Vishnu ended the ever-increasing terrorism of the Asura by finishing them off and burying their heads under the Mandar Parvat. So this occasion also represents the end of the negativities and beging of era of righteous living.