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).
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