The mystery of Uttarayana

Winter Solstice is a significant event and celebrated across northern hemisphere. Winter Solstice occurs on 22 December every year which marks beginning of northward journey of Sun. It brings more sunlight leading to longer days and Sun is important for life on earth. 

In India, this celebrated as Uttarayana. Uttarayana means journey towards north. However it is celebrated around 14-15 January every year. This festival is called Makara Sankranthi. Uttarayana start on the day when Sun enters Capricon constellation.

If Winter Solstice occurs on 22 December why is Uttarayana celebrated on 14/15 January?

As we know seasons occur on earth due to tilt in its axis. The current tilt is 23.5^o.

 

Due to this tilt, as earth moves around the sun, we experience varying levels of sun-light across northern & southern hemispheres. On earth we see this as change in angle of sun movement across the horizon.

 

In northern hemisphere on Winter Solstice (22 December), we Sun at its lowest point and in Summer Solstice (22 June), we see Sun at its highest point. This is opposite in southern hemisphere. Winter Solstice (22 December) marks the day when Sun appears to start its journey northwards. On this day, northern hemisphere experiences shortest day. Summer Solstice (22 June) marks the day when Sun starts its journey south. This is the longest day in northern hemisphere.

In between winter & summer solstices, we experience two special days called as equinoxes. These are 22 March & 22 September. On both these days day and night are equal lengths.

We have defined imaginary lines circling around the globe called Latitudes.

Of these latitudes, 5 lines are significant. On Equinox days, Sun crosses equator. On 22 March defined as Spring Equinox, sun cross equator from southern to northern hemisphere. This event is celebrated in some cultures like Arabs. 22 September is the day of Autumnal Equinox when sun crosses over equator to southern hemisphere. Also on the both these days midday sun is right above our head on equator (i.e. Sun is at 90^o to earth’s surface). That means if you stand on equator at midday, you won’t see a shadow of yourself.

Tropic of Capricon is lowest latitude where midday sun is above our head (i.e. 90^o to earth’s surface). This happens on Winter Solstice (22 December).

Tropic of Cancer is the highest latitude where midday sun is at 90^o to earth’s surface and this happens on Summer Solstice (22 June).

Because of 23.5^o tilt in earth’s axis, Tropics are exactly 23.5^o above and below equator.

Arctic and Antarctic circles are lines which define highest & lowest points where either there is daylight or dark. That is in winter it is complete dark and in summer it is just daylight.

Well! What is all this got to do with Uttarayana on 14/15 January? I’m just coming to that.

As we already know earth’s axis is tilted at 23.5^o. However it is not always been same. It is not constant. It changes between 22.1^o and 24.5^o. It changes over thousands of years.

 

This phenomenon occurs because earth’s rotation is like a spinning top. Which means axis goes in a circle / elliptical shape. While earth is rotating daily, the axis itself rotates over a long period. Due to this phenomenon, the axis tilt changes.

 

With the current angle of 23.5^o, earth’s North Pole is pointing to Polaris. In the past (few thousands of years) it would have been pointing to Vega as we can see in the diagram below.

 

Sometime in the past about 2000 year ago, when Greeks defined Tropic of Capricorn, Sun was entering constellation Capricornus at Winter Solstice (22 December). On Summer Solstice (22 June), Sun was entering constellation Cancer.

In current times, Sun appears in constellation Sagittarius during Winter Solstice (22 December).

In India, we celebrate Uttarayana on 14/15 January when Sun enters Capricorn (Makara rashi) constellation. I think our ancestors started celebrating Uttarayana during the times when Sun entered Capricorn during Winter Solstice. However we are stuck to the tradition and celebrate Uttarayana according to the date when Sun enters Capricorn, whereas actual Uttara Ayana (journey to north) starts on 22 December.

For that matter, we should even rename our tropics for current times. Tropic of Capricorn should be called as Tropic of Sagittarius.

 I don't own copyright to any of these images used. I have copied them from web.