What is Makar Sankranthi ?
The transition of the Sun to the zodiacal sign of Makar (Capricorn) to make a change in season. It is celebrated in the south as Pongal or Makar Sankranthi, north as Lohri, in Assam as Bhogali Bihu.
Why the Difference Between the festival date from one astrologer to another:
Reason: The Transition(travel) of Sun from Dhanus (Saggiratus) to Makar (Capricorn) in going to happen at the Afternoon of 14th Jan. So, the ritual related to makar sankranti is to be perormed on next day i.e. 15th Jan
According to the telangana vidvadsabha the festival dates are like
Bhogi: 14th January
Sankranthi: 15th January
Kanuma: 16th January