Makara (month) month of Kumbha. The start of this month is almost always January 14, the day of the Makara Sankranti festival, and periodically the Kumbh Mela. The Makara month is called "Tai" in the Tamil Hindu calendar. The ancient and medieval era Sanskrit texts of India vary in their calculations about the duration of Makara, just like they do with other months. For example, the "Surya Siddhanta" calculates the duration of Vrschika to be 29 days, 10 hours, 45 minutes and 12 seconds. In contrast, the "Arya Siddhanta" calculates the duration of the Vrschika month to be 29 days, 10 hours,
Aryabhata 23:56:4.091. Similarly, his value for the length of the sidereal year at 365 days, 6 hours, 12 minutes, and 30 seconds (365.25858 days) is an error of 3 minutes and 20 seconds over the length of a year (365.25636 days). As mentioned, Aryabhata advocated an astronomical model in which the Earth turns on its own axis. His model also gave corrections (the "śīgra" anomaly) for the speeds of the planets in the sky in terms of the mean speed of the Sun. Thus, it has been suggested that Aryabhata's calculations were based on an underlying heliocentric model, in which the