सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

121 does not alter the mathematics that goes into his rectifi- cation. According to modern astronomy the Sun and the Moon, one relatively and the other directly go round the Earth, in ellipses, the Earth being in one focus whereas in Hindu astronomy both the Sun and the Moon are taken to be going round the Earth in eccentric circles i.e. circles whose centres do not coincide with the centre of the Earth. In fact, Bhāskara says in so many words “ भुमेर्मध्यं खलु भवलयस्याऽपि मध्यं यतः स्यात् , यस्मिन् वृत्ते भ्रमति खचरो नाऽस्य मध्यं कुमध्ये, भूस्थो द्रष्टा न हि भवलये मध्यतुल्यं प्रपश्येत्, तस्मात् तद्ज्ञैः क्रियत इहतत् दोःफलमध्यखेटे i.e. The centre of the celestial sphere coincides with the centre of the Earth. The centre of the circle in which a planet goes does not coincide with the centre of the Earth. Hence an observer on the surface of the Earth finds the True planet’s position differing from that of the mean planet, so that what is called the correc- tion of Bhujaphala is to be made in the mean position of the planet to get the True position.” Here it has to be noted that the Bhujaphala mentioned stands both for the equation of centre and the second equation known as Sīghraphala as well. One may wonder how it could be so, but it may be noted that in the formulation of both the equations, the centre of the eccentric does not coincide with that of the Earth and also in both the cases the equa- tion contains the term H sine of the anomaly where the word anomaly whether it be of the first or second equation is known as ‘Bhuja’. . In the case of the other planets, the fact is that they go round the Sun in elliptic orbits, the Sun being in one focus. In Hindu Astronomy, we shall see that the centre of the eccentric circle in which these planets are taken to revolve coincides with the Sun. Hence, though the ancient Hindu Astronomy postulates geocentric motion, the mathe- matics that goes into the formulation of the second equa- tion, makes the Sun’s centre the centre of planetary revolu- tion. One may wonder again how the equation of centre 16