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

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should be also 12° for the occurence of an eclipse. Since
it is customary to check the occurence of an eclipse
through Sapātasūrya ie. longitude of the Sun with respect
to the node (the prefix Sa is to signify that the sum of the
Sun's longitude and that of the node should be taken, as
the longitude of a node is measured in the opposite dire-
ction from the zero-point of the ecliptic) it is stipulated
that the Sapātasūrya should be 12° for the occurence of a
lunar eclipse. But, as the True Sun might differ from
the Mean by about 2°, and as we are concerned with the
True Sun only, the limit is increased by 2°, so that a lunar
eclipse may occur if the Sapātasūrya happens to be less
than 14°. Thus there is no more complication with res-
pect to the occurence of a lunar eclipse than requiring the
longitude of the Sapātasūrya to be less than 14° for the
occurence of a lunar eclipse. If this condition be satisfied,
there will be an eclipse and that will be visible at all
places, where there is night, since a body in shadow will
not be seen from any place whatsoever.
But, there is a complication with respect to the occur-
ence of a solar eclipse namely that it is not a question of
the Sun entering a shadow. The Sun could never be
shadowed. A solar eclipse occurs when the disc. of the
Moon comes in between the Sun and an observer and
obstructs a vision of the Sun's disc. The Moon being very
near us compared with the Sun, its coming in between the
Sun and an observer may well be compared with a cloud
obstructing the vision of the Sun. Just as, when a cloud
obstructs the vision of the Sun for an observer, it could
not do so with respect to another who is situated at a
distance, so also, if the Moon effects a solar eclipse for a
particular place, it could not do so for all places. This is
said to be due to parallax or Lambana as it is called (Refer
fig. 64). It is so called because, when there is an eclipse
of the Sun for an imaginary observer at the centre C of
the Earth, the Moon intersecting in the line of sight to