Significance meaning of Tamil New Year on Thai Month (Suravam) & Pongal Festival.
500 Prominent Tamil scholars under the leadership of Maraimalai Adigal like Professor Namachivayam, K.S. Pillai, Sachithanandam, N.M. Vengadesasamy, V. Kalyanasundaram, Somasundara Bharathiyar, U.V. Swaminatha Iyer, K.V.P. Visvanatham and poet Bharathithasan on Jan 18, 1935 at Pachaiappan College, Chennai Tamil Nadu proclaimed 1st of Thai (Suravam) as Tamil New Year.

It was decided at that conference that the Tamil New Year should be based on the birth of Tiruvalluvar and that first of Thai should be celebrated as Ponggal Tamil New Year.
Dr. M. Varatharajan, a well known Tamil research scholar, has said that in the early period the Tamils celebrated Thai as their New Year and not Chitirai and that is the reason why Ponggal is being celebrated not only in the villages but also in towns and cities.
There is also evidence that Chitirai was introduced only after the 14th century in Tamil Nadu.
The ancient Tamil astrologers studied the revolution of the earth around the sun and noted the movement of sunlight to the north and south of the equator for six months each. This is called as Solstice. The north movement starts somewhere in January, hence the most important one as per as the renewal of the world is concerned.The movement of sunlight towards the north was named Vada Selavu (Uthraayanam) and that towards the south as Then Selavu (Thatchanaayanam). This signals the end of winter and the onset of spring throughout the northern hemisphere. For the next six months, the days are longer and warmer. The Sun begins its journey northward as it transits into the constellation of Suravam (Makaram) – Capricorn, signaling the return of ever increasing daylight and the Sun going to start drive out the darkness. This is pure scientific evidence and nothing to do with religious beliefs.

2 Kanniyam = 1 Nodi
2 Nodi = 1 Mathirai
2 Mathirai = 1 Guru
2 Guru = 1 Uyir
2 Uyir = 1 Sanigam
1/2 Sanigam = 1 Vinadi (second)
60 Vinadi = 1 Naligai
2 1/2 Naligai = 1 Orai
3 1/4 Naligai = 1 Mulutham
2 Mulutham = 1 Yamam
4 Yamam = 1 Poluthu
2 Poluthu = 1 Nal (Day)
15 Nal = 1 Pakkam
2 Pakkam = 1 Matham (Month)
6 Matham = 1 Suyanam
2 Suyanam = 1 Andu (Year)
Hence it is beyond any doubt that the Ponggal festival is the Tamil New Year.
- Notes:
Dr G. Johnson, Masai, Johor Malaysia
Mr Thirumavalavan, Malaysia Tamil Neri Kalagam
Mr Vijayakumar Alagappan, Indian Knowledge System Academy, Malaysia
OMTAMIL.com Online Learning on Tamil Religion, Language & Culture
http://en.wikipedia.org/wiki/Puthandu
http://sharmalanthevar.blogspot.com/2013/03/tamil-new-year-date.html