पञ्चसिद्धान्तिका (आचार्य वराहमिहिर - सूर्य, रोमक, पौलिश, वासिष्ठ एवं पितामह सिद्धान्त)

166 PAÑCASIDDHĀNTIKĀ VI.10 10. Subtract the Head of Rāhu from 12 rāśis, multiply it by 228, and add the Moon's longitude. If this is between 6 and 12 rāśis, the Moon is farther, and if between 0 and 6 rāśis, it is nearer. (The idea is, that the nearer this sum is to 9 rāśis, the farther is the Moon and its colour at total eclipse is nearer to red. The nearer this sum is to 3 rāśis the nearer is the Moon, and its colour is nearer to brown). Since this Siddhānta uses the latitude, (or Moon ~ Rāhu) at full moon to find the duration, the part of the duration before full moon is equal to that after full moon, and the middle is at full moon. But other siddhāntas repeat the work, using the latitudes at first and last contacts separately, so that the two parts are not equal, and the middle does not occur at full moon. Still all siddhāntas techni- cally call the moment of full moon as the middle, since at that time the eclipse is practically the maximum. As for the colour of the Moon at eclipse, it is based on observation, and given slightly differently by different Siddhāntas. Some take the fraction of the Moon eclipsed as the criterion for the colour, others the time of the eclipse and its nearness to sunset or sunrise, etc. Here, this Siddhānta uses, in addition, a new criterion, not given by any other Siddhānta, viz. the distance of the Moon from the observer, and there is truth in what the Siddhānta says. Here, it may be asked how at all is it possible for the Moon to have any colour at eclipse. It is an opaque body, and what illumination it has comes from the Sun's rays falling on it. When it is immersed in the Sun's umbra, i.e. full shadow, (we consider the Moon in umbra alone as eclipsed, and not in pen-umbra), the Sun's rays cannot fall on it. It cannot be the earth-shine falling on the Moon and dimly illuminating it, as in the crescent Moon, giving rise to the popular belief of "the old Moon in the arms of the new". At times of new moon, when the lunar eclipse occurs, there is no earth-shine opposite the Moon to illuminate it. This is the answer: Though the Moon is in the earth's shadow geometrically speaking, the Sun's rays, refracted by the earth's atmosphere, fall on the Moon and illuminate it with a red or brown glow, red light alone being able to reach the Moon after passing through the long section of the earth's atmosphere undispersed, on account of its greater wave-length. (See fig. 6). 8A.9. Quoted by Utpala on BS 5.18 8A. Om both in A and B, but included in this edition on account of its essentiality in verses 10-14 as 11-15. this context and its being quoted as a verse of VM by Utpala in continuity c. A.B. उद्यास्तांगांसधूम्रं (b. धूम्र); C. उद्यास्तग्रासधूम्रं with verse 8. d. A.B.C. ०णे च सलिलाभम् (B. om च) While C om its this verse since it is not 10a. D. मुखोनचक्रं available in the text mss. D adds it. b. A.B.C.D. त्रियमद्भिगुणं; D. शशि [हीन] संयुक्तम् (as no. 9, and the further verses (A. संयुक्तन्) numbered as 10 etc.) since Utpala has it. c. A.B. एपिक्लेशोयमुक्ष (B. क्लेशो), (A2 यमुध); C. एभिः क्लेशोऽयमुच्चं; D. अभिक्लॆशोऽयमुच्चः 9a. A. पर्वग्रांसिन्येवं; C. ग्रासे पीनं d. D. क्रियादिः. B. गो नीयः; D. गो नीचः D. numbers the verse as 10 and the