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

68 PAÑCASIDDHĀNTIKĀ III.29
(a). Rāhu's motion for 75,500 days = 8 × 75,500 divided by 151, degrees = rev. 11-1-10-0. The
exact motion = rev. 11-1-10-0 + 11 minutes = rev. 11-1-10-11 = rā. 1-10-11, omitting full revolu-
tions. Rāhu's Head = rā. 7-25-59 – rā. 1-10-11 = rā. 6-15-48. Tail = rā. 6-15-48 – rā. 6-0-0 = rā.
0–15–48.
As the motion of Rāhu is zero, the Head of Rāhu is the constant itself, viz. rā. 7-25-59.
As the motion is 8° in 151 days, according to this Siddhānta, to move 360°, i.e. one revolution, it
takes 360 × 151 ÷ 8 = 6795 days. But during this period it moves one minute more, i.e. the exact
motion is 360° 1' in 6795 days, i.e. one revolution takes 360° × 6795 ÷ 360° 1' i.e. 6794 days, 19
nāḍīs.
We have seen that the Head of Rāhu for the Epoch, according to the Pauliśa is the constant itself,
viz. rā. 7-25-59. According to the Saura (condensed by the author) it is rā. 7-26-6. According to the
Vākyakaraṇa it is rā. 7-26-11. According to modern astronomy, taking the ayanāṃśa as being zero for
the period it is rā. 7-26-0. According to the Siddhānta Śiromaṇi it is rā. 7-27.13. We see that all except
the value of Śiromaṇi agree closely, verifying the Pauliśa value for the Epoch. The disagreement of
the Śiromaṇi value is only apparent, for the zero point of the Śiromaṇi zodiac is about one degree
behind that of the rest, (as may be seen by comparing with its co-ordinates of the stars or from its
Sun being one degree more than that of the rest) and if the same point is taken as the origin, the
Śiromaṇi too gives about rā. 7-26-13.
Thus the value at epoch is necessary to get the Rāhu at any moment, and it is this that is given
by Vṛścikabhāgā Rāhoh etc. But TS have not understood this need (as they did not understand
the need for the kṣepa in the case of the Moon (see II.3) and gave a wrong interpretation of
śaśimuninava-yamāśca rāśyādyāḥ) and give the following laughable explanation: "The measurement
of the limbs of Rāhu having the form of a scorpion is 25 minutes. Deducting this from the motion
of Rāhu obtained from (28), the head or face of Rāhu is to be found. This plus six rāśis is the tail.
We have to rely only on the words of the ancients to know that the scorpion-like limbs of Rāhu mea-
sure 25 minutes, there is no other reason." Now we ask: Let it be that they have not understood the
need for the kṣepa. How did it not occur to them that Rāhu can be got only by deducting the motion
from something, whether it is a cycle or some other constant, because the motion is retrograde (as
they themselves have said in other places: "Rāhu deducted from a full revolution is the Head, this
plus six rāśis is the tail", IX. 6, "deducted from the end of Pisces is the head", VIII. 8). It also appears
here that Thibaut is not satisfied with Sudhakara's explanation. Further, how did it not occur to
them that ekaliptikāluptāḥ ṣaḍviṃśativṛściakabhāgāḥ, means rā. 7-25-59, when they have correctly inter-
preted siṃhasya vasuyamāṃśāḥ as (XVI. a) rā. 4-28-0, sārdhāḥ pañcālino (XVIII. 1) as rā. 7-5-30, nava
sārdhāḥ kanyāṃśāḥ (XVIII. 11) as rā. 5-9-30, ṣoḍaśa vṛṣabhasyāṃśāḥ nava liptikāvarjitāḥ (XVIII. 18) as
rā. 1-15-51? It is really astounding what tricks the mind can play!
Incidentally, the following should be mentioned here for general information. Following the
nomenclature of the ancient Saṃhitās, the author calls the ascending node Rāhu's head, and the
descending node 'Rāhu's Tail', both being Rāhu, though generally in later astronomical works the
word Pāta is used. In recent times, somehow the term Ketu has come to be applied to the descending
node, Rāhu being retained for the ascending node, though there is no authority in astronomical
works or Purāṇas to bring in Ketu here. The ancient Saṃhitās use the term Ketu for the
Dhūmaketūs or comets and, as deities they are generally referred to in the plural. They are also
characterised by unpredictable motions and in the Bṛhatsaṃhitā too the author says so. (This is the
view of the ancients though we now know that a number of them are periodic, and their positions
can be predicted with tolerable accuracy). They are worshipped in the collective, as seated on doves,