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

347
Chālana is as follows. At first knowing the elongation of
the Moon at Sunrise, by rule of three, using the then daily
motions of the Sun and Moon, the moment of the
conjunction is to be computed. Again the positions of
the Sun and Moon are to be computed for that moment
and also their daily motions are to be rectified for the
moment. With these rectified daily motions and with the
then positions of the Sun and the Moon, again the
moment of conjunction is to be computed. Repeating the
process till an invariable answer is reached, we have the
exact moment of conjunction. For that moment, the
position of the Rāhu is also to be calculated. Similar
is the procedure for a lunar eclipse also. It is to be
noted that the correction called Natakarma, which we
formerly identified to be the correction for ' Astronomical
Refraction' is also prescribed here as particularly
mentioned by Bhāskara, in the commentary. (Vide verses
68, 69 Spaṣṭādhikāra).
Verse 3. The magnitndes of the orbits and the .
orbital radii of the Sun and Moon.
The distances of the centres of the globes of the Sun
and the Moon from the centre of the Earth in yojanas are
respectively 689377 and 51566.
Comm. We saw in the Kakshādhyāya of the first
chapter as to how these distances were estimated. Some
scholars pronounced these distances are parameters; but
as per the modern estimate of the Earth's radius as
compared with that of Bhāskara, (The method indicated
by him in the Bhuparidhimānādhyāya of chapter I, is
quite mathematical) a yojana equals five modern miles
and with this correspondence, the distance of the Moon
is very near the truth. So to say that the distances
given above are mere parameters is wrong; also if one
of the parameters gives a correct value of the quan-