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

GRAHACCHĀYĀDHIKĀRA Verse 1. The orbital inclinations of the planets. The inclinations of the orbits of Mars, Mercury, Jupiter, Venus and Saturn to the ecliptic are respectively 110, 152, 76, 136 and 130 minutes of arc. The nodes of Venus and Mercury get rectified by adding their respective Śīghra anomalies to their values obtained originally. Comm. The values given above are said to be the mean values. Those given for the superior planets namely Mars, Jupiter and Saturn approximately accord with their modern values. Bhāskara says that these values pertain to that moment of observation, when the Śīghra anomaly is equal to 90 + ½ H sin⁻¹ a where a is Hsine of the maximum Śīghraphala. This is quite in order because when the Śīghra anomaly assumes the said value, the true planet is at the point of intersection of the deferent and the eccentric, which means that the planet is equidistant from E₁ as well as E₂ (vide fig. 103). Identifying E₁ to be the earth's centre and E₂ to be that of the Sun in the case of the superior planets, the mean latitude of the planet observed will be the same as that observed either from the earth or from the Sun. Hence in the case of the superior planets, the maximum latitudes of the planets observed accord with the geocentric as well as heliocentric observation. These are taken to be the mean values of the maximum latitudes. In the case of the inferior planets, it will be clear why the modern values of 7° and 3°-24' for Mercury and Venus are far higher than the Hindu values namely 152' and 136'. Since the mean planet in this case is taken to be the Sun, the linear values of the latitude observed from E and S, the centres of the Earth and the Sun respectively will be in the ratio SP/ES (vide fig. 104). 57