Uttarayan and Dakshinayan

The apparent northward movement of the sun is a phenomenon that happens due to the earth rotating around an axis. When an observer observes the sun from a fixed point on earth, it seems that the sun is moving when it is not. This is caused due to the way the light hits the earth at specific angles because of the rotation. Sun is at the focus of the ellipse which is a point at the side of the ellipse but not at the center. The closest point on the ellipse when the earth is the closest is called the perihelion and the farthest point between the sun and the earth is the aphelion. 

Movement of Sun

The imaginary path around which the earth orbits the sun or the ellipse is not completely circular but elliptical. In India, the movement of the earth has been given two distinct names- uttarayan and dakshinayan. Uttarayan is when the sun moves from the south to the north. Both of these movements have distinct cultural and religious meanings in India. The northward movement of the sun is uttarayan. During this time, the sun shifts from the Tropic of Cancer towards the north. 

The movement of the Sun

The northward movement of the sun or the uttarayan is the northward migration of the sun from the south. It starts during the winter solstice and begins on 21st December every year. The sun gradually begins to move north throughout December and continues well into June when the summer solstice begins, roughly around the 21st of June.  The uttarayan is a very auspicious time for many religious Hindus. Important to the discussion of uttarayan is its opposite phenomenon of dakshinayan. The sun during this time travels back from the Tropic of Cancer to the Tropic of Capricorn. Here nights are longer than the days. During the northward movement of the sun, the days are longer than the nights. It begins on either 21 June or 22nd June. Important to these movements are the concepts of the equinoxes. Equinox is a time when the sun appears directly over the equator thereby resulting in an equal amount of day and night. In India, the equinox will be on 23rd September 2022. 

Solstice

The solstice is a time when the sun is the farthest from the earth. It happens twice a year, once in each hemisphere. In India, the solstice happens during the winter. It is known as the winter solstice. During this time, the earth is tilted farthest from the sun due to its axis. During the solstice, the daytime is the shortest with the night-time being the longest. The solstice is about to occur in India on 21st June 2022. 

Winter, Autumn, and Monsoon

The seasons of winter, autumn, and monsoon happen due to the rotation of the earth. Seasonal changes happen in each hemisphere due to the revolution of the earth around the sun and its rotation on its tilted axis. The differences between uttarayan and dakhsinayan are also visible through the seasons. The uttarayan begins at the tail end of winter continues through spring and summer and reaches its end near the onset of monsoon. The dakshinayan on the other hand starts from the monsoon and covers autumn and winter. 

Conclusion

Both the dakshinayan and the uttarayan are a part of the religious and spiritual cultures of India. There is scriptural importance attached to equinoxes, solstices, and the movements of the sun between the tropics. The difference between the two arises out of the time and the direction in which they occur.