10. ASTRONOMICAL BASIS OF THE SEXAGESIMAL
The first two mean Solar motions, a year consisting of 360 + 6 Earth revolutions, generate the sexagesimal number system in its entirety. These two mean motions of the Sun form the basis for the 366 day year of the Jyotisha Vedanga and are discernible in the SuryaSiddhanta from the fact that the radius of the orbit of the asterisms is given as 60 times that of the Sun. Since in this astronomical system the speed of rotation of a body varies as the inverse of the radius of its orbit, this implies that the asterisms should rotate six degrees while the Sun is rotating 360 degrees.