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

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εA is a tangent to the Moon's disc and M the centre of
the Moon, Sin B = r' / d where B is the angular semi-dia-
meter of the Moon's disc, r' = the spherical radius of
the Moon's disc measured in yojanas, so that since
Sin B = B' in Hindu trigonometry when the angle is small,
2πr' / 2πd = 2πr' / 324000 = 16 / 3438 ∴ 2πr' = (324000 × 16) / 3438 ; hence
r' = (18000 × 16) / 191 × 7 / 44 = 504000 / 2101 = 240 yojanas.
Bhaskara gives the semi-diameter of the Moon's disc to be
16'-0"-9"' so that the above r' is very approximately 240
yojanas as given by Bhaskara.
Now with these constants pertaining to the Moon's
distance, and his spherical radius, it was sought to find the
spatial distance traversed by the Moon during a day. The
rule of three used was " If 16'-0"-19"' of the Moon's angu-
lar semi-diameter pertains to a spatial distance of 240 yoja-
nas at his orbit, what does the mean daily motion of
790'-35" pertain to ? " The answer is 683064000 / 57609 = 11858¾
yojanas as given by Bhaskara elsewhere or taking the
Moon's mean semi-angular diameter to be 16' only, and
using the rule of three " If 16' at the lunar orbit correspond
to 240 yojanas, what do 790'-35" correspond to " we have
(790'-35" × 240) / 16' = 15 × 790 7/12 = 5/4 × 9487 = 9487 + 2371¾
= 11858¾ yojanas as given by Bhaskara.
Thus having obtained the daily spatial motion, the
Hindu Astronomers assumed all the other planets (includ-
ing the Sun) to have the same daily mean spatial motion.
On this assumption since the, Moon's orbit will be
27.3217 × 11858¾ = 324000 yojanas, and the circumference
of the universe will be 324000 × 57753300000
= 18712069200000000 yojanas the Sun's orbit will be
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