Astronomy and Cosmology

Author(s): L C Jain
Publisher: Rajasthan Prakrit Bharti Sansthan Jaipur

Page 62

The moon
The rahu
or 12
The kinematic motion of the nakşatras is actually due to the rotation of the earth, Keeping or regarding them as fixed, the relative motion of remaining bodies with respect to the nakşatras can be found to be 5, 67, and 5 celestial parts per muhurta. 12
1
2
61
Now the rahu, as it appears from the Trilokasara (11th century), is a fictitious body meant for a seasonal or sayana tu or karma year (samvatsara), By this rahu, celestial parts are traversed in
61 12
of a solar
1768 celestial parts
11
1829
12
day, hence the stretch of a zodiacal sign of 300 or 4575 celestial parts is travelled in a month of 30 solar days. Thus 54900 celestial parts are traversed in 360 days or twelve months. This rahu, thus defines the mean annual
1
motion of the sun, which describes 1830 celestial parts in
30
of a day or 3600 in a day which defines the basic unit, solar day, used in astronomy. The Tattvarthasūtra also describes, "The astral bodies the sun, the moon, the planets, the constellations and the scattered stars, in the human region (nploka), are characterized by incessant motion around Meru, and they cause the divisions of time.90
RELATIVE MOTION OF NAKSATRAS
such revolutions make 359
""
The daily motion of the nakşatras is defined as 1835 celestial parts muhurta or 48 minutes. Thus 54900 celestial parts or
degrees per
35 1835
د.
1830
1060
3600 are covered in 1835 part of a day, or 23 hours 56 minutes and 4 1835
seconds. Modern value of such a sidereal day is 23 hours 56 minutes 4.1 1685
seconds. Thirty such revolutions make 29 1835 days. Three hundred sixty
days. Three hundred sixty-six such revolu
5 days. Relatively this will be regarded as rotation of 1835 respect to a fixed nakşatra or a star therein, without any as the first point of Aries has at the rate of 50."2 per
tions make 365 the earth with proper motion annum).
90. Cf. Reality, op. cit., ch. 4, vv. 12-14,
43
1
30