Pongal on 15th January..instead of 14th!!

HAPPY PONGAL and belated MAKARA-SANKRANTI to everyone.

However, This is a phenomenon happening regularly during the past few years, that I found to be strange. The harvest festival of Pongal seems to fall on 15th of January rather than 14th of January (thus coinciding with Sankaranti). The inexplicable point is that both festivals are based on the Solar Calender and are supposed to mark the start of Uttaranayam or Makara-Sankramanam(that sounds close to Makara-sankranti. Doesn't it?). So, should they not fall on the same day??

One more cause of confusion was the "Makara Jyothi", which gave a darshan yesterday at Sabarimala to lakhs of people (and to crores more through TV channels) yesterday. A day before Pongal festival, which, according to my family 'vadhyar' falls on 15th January this year and so does 'Makara-Sankaramanam'.

I am confident on the mathematical ability of

• the Telugu astrologers who calculated Sankaranti to be on 14th.
• the 'forces' which caused Makara-Jyothi to appear on 14th
• the Tamil panchangam-makers who predicted Pongal on 15th
• the vadhyar, who said that 'Makara-Sankramanam' (and its associated rituals) should be performed on 15th.

So, where is the discrepancy? Have I missed something? Are there two different Solar Calenders, which have slightly different lengths for their years? What could be the reason???

I am really confused!!!