The science of Sankranti.

Dawn on Sankranti. Note the sun's position at the southern end of the horizon.
Dawn on Sankranti. Note the sun’s position at the southern end of the horizon.

What exactly is Sankranti?

Many of our religious festivals originate from ancient Indian astronomy. These festivals commemorate important astronomical events.

Actually, there is a Sankranti every month of the year. The term ‘Sankranti’ is not religious, but an astronomical one. It is used to denote the apparent movement of the Sun from one constellation to another.

The Sun, of course, does not really move with respect to the Earth. Its lateral movement across the skies is an illusion caused by the tilt in the Earth’s axis.

The Earth, as you know, rotates around its own axis, making one circuit every twenty four hours. It rotates at an astonishing speed of about 1600 km/hour. That’s much higher than the speed of sound.

The cycle of day and night is due to the Earth’s rotation. But that doesn’t explain why we have so many seasons in a year. If the Earth’s rotational axis were vertical, then each side of the planet would have the same temperature, during the day or night. And we would have only one season throughout the year.

The Earth’s axis of rotation isn’t vertical, but slightly titled at an angle of 23.5 degrees. That results in a phenomenon called precession and causes varying temperatures across the globe, and the creation of different seasons in a year.

Indian astronomers knew about the precession of the Earth’s axis. They even had a mathematical formula to precisely calculate precession and they had an official term
for it – Ayanamsa.1200px-Earth-lighting-winter-solstice_EN (1)

In addition to creating seasons in a year, the Earth’s precession also results in the apparent lateral movement of the Sun, with respect to the horizon. Ancient Indian astrologers would track this movement by using stellar constellations as reference points. Thus, the Sun would apparently move from one constellation to another during the year. This transition was referred to as ‘Sankranti’ or ‘Sankramana’.

With respect to the horizon, the Sun apparently moves to the north or south, during the year. You can observe this movement at sunrise. Over a period of months, the Sun will appear to move to the north or south, as it rises.

So, if there’s a Sankranti every month, what’s the big deal about Makara Sankranti?

Well, in Indian astrology, Makara Sankranti is given great significance because this particular Sankranti marks the beginning of the Sun’s movement to the north. From this Sankranti onwards, the Sun enters the constellation of Capricorn (known as Makara in Sanksrit). And moves into the northern hemisphere.

This northern transition of the Sun is called Uttarayana. From today, for the next six months, the Sun will continue its northerly movement. And six months later, the Sun will begin its apparent movement to the south, called Dakshinayana. This Sankranti is known as Karka Sankranti, and falls between July 14 and July 18.

Makara Sankranti marks the end of winter, and the start of the harvest season. It also marks the end of an inauspicious period.

In the Mahabharata, this is the day on which Bheeshma chose to release himself from his body – after he was assured that the kingdom of Hastinapura was in the safe
hands of Yudhistira and his brothers. Before he left the Earth, Bhishma imparted the secret of the Vishnusahasranama to Yudhistira. Vishusahasranama, or the Thousand
Names of Vishnu, is considered one of the most powerful incantations in Sanatana Dharma.

Makara Sankranti, therefore, is considered a sacred day, a day on which the rays of the rising Sun bring enlightenment to human beings.

On this day, the Sun is worshipped throughout India. Til, or sesame seed, is used across India as part of the rituals. In Maharashtra and Karnataka, people distribute laddoos made of til and jaggery. In many parts of west and north India, people mark the festival by flying kites of all shapes and sizes.

So, til-gul ghyaa, god god bola. And go fly a kite.

Happy Makara Sankranti, everyone.



4 thoughts on “The science of Sankranti.

    1. Hi Gopal:

      Every month, the Sun apparently moves from one constellation (or Raasi) to the next. The transit of the Sun is not real, of course. It seems to move across the constellations because the Earth is slowly but constantly wobbling as it rotates on its axis – just like a spinning top wobbles on its axis as it slows down. The Sun’s position is fixed. It is the Earth that is wobbling, and the wobble creates the illusion that the Sun is rising from a slightly different position each day.

      You can observe every morning at sunrise. From this month onwards, the Sun will seem to move towards the north. If you observe sunrise today and mark its position on the horizon, and observe it one month from now, you will see that the position of the Sun at sunrise is slowly moving northwards.

      The constellations themselves are imaginary. Ancient Indian astronomers observed that certain stars in the night sky were apparently arranged in specific patterns that resembled familiar objects – like a goat, or a lion, and so on. Each of these star clusters were given a name based on what they seemed to resemble. Indian astrology (and ancient astronomy) recognises twelve major constellations in the night sky. The movement of the Sun is recorded with reference to these twelve major constellations.

      The Sun takes a month to apparently transit from one constellation to the next. This month the Sun is in Makara, i.e. Capricorn. After about a month, it will seem to be in Aquarius, i.e. Kumbh Raasi.

      Each such monthly transit of the Sun is known as Sankramana or Sankranti. That is why there is a Sankranti every month. Six months from now, the Sun will enter the northernmost constellation, i.e. Cancer or Karka raasi. This is known as Karka Sankranti. After this, the Sun will again seem to move southwards, in the reverse direction. till reaches Makara again in January 2016.


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