Makara-Sankranti (the junction of the capricorn), when the Sun enters the tenth house of the Zodiac, about the middle of the month of January, which is regarded as a kind of New Year by many. Bhishma of the Mahabharata fame waited for the beginning of the Northern course of the Sun, to leave his mortal coil. The seventh day of the bright half of the month of Magha (January-February) is called Rathasaptami, and is supposed to be the day on which the Northern movement of the Sun takes definite effect, and is traditionally regarded as the day when the chariot of the Sun is diverted to the North by his charioteer, Aruna. The plant which is sacred to the Sun is called Arka, whose leaves are placed by people on their heads when they take the sacred bath on this day. http://www.dlshq.org/religions/theology.htm