India is today celebrating Makar Sankranti and people are wishing each other on this auspicious day. This auspicious day is celebrated in different parts of India in different ways such as Lohri, sankrant, kite festival etc. It is also celebrated as Uttarayan, a six month period considered very auspicious and in which Bhishma Pitamah, a great warrior in the Greater India war (Mahabharata) chose to leave his mortal body. However while it is a fact that Uttarayan was once coninciding with Makar Sankranti (the point in the celestial sphere when earth enters the zodiac sign of capricorn) it is no more true in our times.
Uttarayan is made up of two words – Uttar (North) and Ayan (motion). It can mean one of the two things either movement in north or movement towards north. However the current makar sankranti is none of it and therefore does not qualify to be Uttarayan.
So lets understand it from the motion of Sun as seen from a given point on the equator. From the horizon where when the Sun rises, it can be understood to be in the north and when it sets it goes to the south. However, the direction of Sun’s motion is northward from midnight point (under our feet) to the noon point (zenith) above our head. From noon to midnight the sun starts descending and becomes southward and finally goes into south while it sets on the horizon. This analogy was given only to explain those who are not very familiar with celestial terminologies. In the celestial plain something similar happens. Lets understand it.
Due to the axial tilt of earth celestial equator cuts the ecliptic on two points which are exactly
opposite each other. These points are called as vernal equinox and automnal equinox. Vernal equinox falls near 21st march and automonal equinox falls near 21st september. These are also the times when days and nights are equal on the equator. Both the ecliptic and celestial equator forms an angle which is equal to the tilt of the earth i.e., 23.5 degrees. In the celestial plain the earth is on the north of the celestial plain from 21st march to 21st september with the point near 21st June being the highest altitude. 21st June is also the longest day and is called summer solistice. From Summer solitice the earth starts descending towards south and cuts the celestial plain on 21st september when it enters south of celestial plain.
Now the question is why there is this misconception on Uttarayan. The answer is that the equinoxes are moving clockwise at a rate of 50.8 seconds per year and in 70.8 years they nearly make a difference of a day. So every 70.8 years all the four points mentioned above i.e., vernal equinox, summer solistice, automnal equinox and winter solistice will move a day backward. So nearly 6360 years later the winter solistice that today falls on 21st december will be on 21st June which will become the point of shortest day.
The question therefore is whether Uttarayan is the six month period of northward motion which is between winter solistice of 21st december to summer solistic of 21st June or Uttarayan is the motion in the north which is from vernal equinox when sun actually enters into the northern zone and remains until 21st september which is the point of automnal equinox. Scholars like Bal Gangadhar Tilak have advocated for the later which is the motion in the north. To me while it looks more logical, I leave this artical open ended to elicit more views.
The medieval period or the dark age of India was known for the destruction of vast amount of knowledge base, libraries, scientific research etc. Ancient India was full of astronomical observatories, ruins of which we can still find at various historical places. The purpose of these laboratories was to carefully observe celestial objects and correct the periodical anamolies of time. That however ceased to happen with series of external invasions by barbarians and thousand of years long struggle for the survival of the civilisation. The time has now come when serious research on ancient Indian civilisation must be done for the greater benefit of humanity.