MAKAR SANKRANTI

Sankranti is one of those rare Hindu festivals which is based on a solar event, where as the prominent Hindu calendar itself is actually a lunar calendar. Which is why we find that the calendar dates of all Hindu festivals keep changing every year, because lunar calendar is based on motion of the moon and the calendar dates are based on Sun (Earth’s motion around Sun).
What is the Significance of Makara Sankranti?
Makara Sankranti, more popularly known as Sankranti is the day on which Sun enters the zodiacal sign of Capricorn (Makara).
This is celebrated on January 14/January 15 every year.
Makara Sankranti is also celebrated to mark the beginning of Uttarayana - the northward journey of Sun in the sky. This is WRONG in today’s context because Uttarayana DOES NOT start on the day of Makara Sankranti anymore! Let me explain why.
What is Uttarayana?
Uttarayana starts on the day of Winter Solstice i.e when Sun begins its northward journey in the sky as observed from Northern Hemisphere. What this means is that from the day of winter solstice onwards for the next six months Sun will make a northward journey towards the tropic of Cancer. Uttarayana means northward journey (Uttara=North and Ayana=journey in Sanskrit).
[NOTE: In the southern hemisphere this marks Dakshinayana i.e Sun starts a southward journey as observed from southern hemisphere on the day of winter solstice of northern hemisphere. Please see Astronomical Dating of Vedic Ages for more details about equinox and solstices.]
Why are Makara Sankranti and Uttarayana events not on the same date today?
Sun entering Capricorn is Makara Sankranti. Makara means Capricorn and Sankranti means change for the good ( Samkyak Kranthi ithi Sankranti in Sanskrit meaning Change for the good is Samkranti)
Uttaryana on the other hand is the beginning of the northward journey of Sun in the sky and this happens on the winter solstice when Sun touches the Tropic of Capricorn which is 23.5 degrees South.
So Makara Sankranti is when Sun enters Capricorn and Uttaryana is when winter solstice occurs.
About 2000 years ago, the events of Sun entering Capricorn and winter solstice coincided with each other. Which is why in those days, Uttarayana was celebrated on the day of Makara Sankranti.
Actually there are 12 sankrantis each corresponding to the Sun entering each of the 12 zodiacal signs. For ex: Mesha Sankranti is when Sun enters Aries, Tula Sankramana is when Sun enters Libra, etc. And yet Makara Sankranti was celebrated as a popular festival in the ancient times because Uttarayana (Winter Solstice) took place on the same day in the ancient times.
But today its NOT the case. Today Sun enters Capricorn on January 14/15 January 21, where as winter solstice takes place on December 21/22!
Winter Solstice was also the festival that was celebrated by the Roman Pagans (which then occurred around December 25) before Christianity entered Rome, which is why Church declared it as Christmas to overshadow the pagan festival. See the Birthday of Christ for more details.
So presently we should be celebrating Uttarayana on December 21 or December 22 when the actual winter solstice occurs. Which is why I said, Happy Makara Sankranti, but belated Uttarayana!
In fact even Makara Sankranti should be celebrated on January 21 today, because that is when Sun actually enters Capricorn today.
Also the real reason for celebrating Makara Sankranti was Uttarayana, and hence we should be celebrating it on December 21/22 NOT on January 15.

A traditional rangoli (Decorative Art) painted on Sankranti. Image: http://www.flickr.com/photos/srikanthmanda/3329699792/sizes/z/in/photostream/

Why do the dates of Makara Sankranti and Uttarayana change?
In the not so ancient times Makara Sankranti and Uttarayana coincided, and people continue the same practice even today by celebrating Uttarayana on the sameday of Makara Sankranti, which is incorrect. Today both Makara Sankranti and Uttarayana occur on different dates and both the events are separated by almost a month.
For instance, at one point of time in the vedic civilization, Sun was in Kumbha (Aquarius) during the Uttaryana (winter solstice). More specifically sun was in Purvabhadra (Pegasi) star of Aquarius on the day of winter solstice (Uttaryana) at one point of time in the vedic ages. Then it moved on to Capricorn (Makara) and today its in Sagittarius (Dhanus) on the day of the beginning of Uttarayana (Winter Solstice).
This change of Sun’s constellation during winter solstice is because of the precession of the earth’s axis which causes Sun to rise in different constellations for the same solar events like equinox and solstices, over a period of time. This is a cycle of about 25800 years. So if today Sun rises in Sagittarius during winter solstice, then after about 2100 years it will rise in Vrishchika (Scorpio) during winter solstice and so on, and will return back to Sagittarius on winter solstice after about 25800 years from now.
Today the winter solstice has moved away from Capricorn to Sagittarius, but the celebration of Uttarayana is still fixed with Makara Sankranti (Sun entering Capricorn). In fact even the date on which Sun enters Capricorn today is still a week later (which is around January 21)
Tropic of Capricorn (Makara Sankranti Vratta) infact got its name because Sun was in Capricorn when it touched this circle on the day of winter solstice. Tropic is derived from the Greek word Tropos which means turn, indicating the turn that Sun took in terms of its direction from South to North after it touched this circle. Today Sun is in Sagittarius (Dhanus) when it touches this circle! So today this circle should actually be called Tropic of Sagittarius.
Summary
Makara Sankranti and Uttaryana are two different astronomical events.
2000 years ago, both the events coincided, but today they are about 25 days apart from each other.
The date of January 14/January 15 for Uttaryana as well as Makara Sankranti is WRONG
Makara Sankranti today takes places on January 21 which is when Sun enters Capricorn.
Uttarayana today takes places on December 21 which is when the winter solstice occurs in the northern hemisphere.
Also most astrologers today make incorrect predictions because they DO NOT consider the precession of earth’s axis and end up drawing wrong birth charts and make wrong predictions. I am not an expert on the accuracy of astrology, but definitely know that NOT including the precession in the calculations of astrology is WRONG. Considering a different star/constellation, when the actual event took place in some other star/constellation, is definitely not correct astrology.