The festival of Makar Sankranti was celebrated recently on January 15th. This festival marks the first day of sun's transit into the Makar Rashi (Capricorn). It is believed that from this day onwards, the cycle of longer days begins. It is one of the few festivals that is observed according to solar calendar.
Makar Sankranti is known as as Maghi or Lohri in North India, Makara Sankranti in Hamarashtra, Pedda Pandaga in Andhra Pradesh; and is also celebrated in West Bengal, Karnataka and Telangana. This festival is known as Sukarat in central India, Magh Bihu in Assamese, and Thai Pongal by Tamil Nadu. To mark this occasion, Sriram had recorded this episode – chants of Lord Surya (Sun) from the 37th mantra from 10th mandal of Rigveda. You can learn more about Makar Sankranti and the 10th mandal of Rigveda on Wikipedia.