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 23.5o.
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 90o 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. 90o to earth’s
surface). This happens on Winter Solstice (22 December).
Tropic of Cancer is the highest
latitude where midday sun is at 90o to earth’s surface and this happens
on Summer Solstice (22 June).
Because of 23.5o tilt
in earth’s axis, Tropics are exactly 23.5o 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 23.5o.
However it is not always been same. It is not constant. It changes between 22.1o
and 24.5o. 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 23.5o, 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.