We celebrate January 14th as Makar Sankranti — the day on which the sun begins to rise in the Makara Rashi (Zodiac Capricorn), Sankranti meaning entering. On some occasions the Makar Sankranti falls on January 13 or 15. There is a common misconception that Makara Sankranti is the Uttarayana (winter solstice).
From time immemorial, the days on which the sun touches its northernmost and southernmost points are noted. These are called solstices — winter or summer. In Sanskrit, the journey southwards is called Dakshinayana, and the one northward is called Uttarayana, ‘dakshin’ and ‘uttar’ being south and north respectively. The winter solstice falls on December 21st, and hence Uttarayana begins on that day, while the summer solstice falls on June 21st, when Dakshinayana begins.
While the exact day on which the winter or summer solstice occurs remains steady (within one day error), there is a slight change in the way the Earth’s rotation axis is aligned to the sun. Due to axial precession of the earth, the date of Makar Sankranti is shifting away from the actual season. In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body’s rotational axis. In particular, it refers to the gradual shift in the orientation of Earth’s axis of rotation.
Every year equinoxes slide by 50 seconds i.e. approximately 1 day in every 70 years due to precession of equinoxes, causing Makara Sankranti to slide further. As a result if Makar Sankranti is considered as Uttarayana then as it is sliding. Makar Sankranti was on December 31st in ca. 1000 CE. The Makar Sankranti and Uttarayana coincided during the times of Aryabhatta, around 1,500 years ago.
Now Makar Sankranti comes on January 14th, however it continues to hold the importance in Hindu rituals. It marks the beginning of auspicious times. On this day, thousands of devotees take a holy dip in river Ganga and other holy streams. Many Hindu devotees take a holy dip at Ganga Sagar, where river Ganga meets the Bay of Bengal.
Makar Sankranti is about nature, energy of the sun, harvest of new crop, and progress of mankind. Happy Makar Sankranti!
H/T Mayank Vahia