Page:On Chronology and the Construction of the Calendar.pdf/21

11.

We may conclude, that these 28 Moon-stars are very ancient in Chinese astronomy and existed already about the time of the emperor Yao, from a remark in the Shu-king, according to which at that remote time the sign of spring was the Moon-star, then called niao, at present called sing; the sign of summer the Moon-star, then called ho, at present called fang; the sign of autumn the Moon-star hiu and the sign of the winter solstice the Moon-star mao, that is, to say at the time of Yao, about 2300 years B. C., these stars stood at sunset in the meridian, when the corresponding seasons commenced, or, in other words, the difference in rightascension between Sun and stars was nearly ninety degrees or 6 hours.

As the declinations and latitudes of these four Moon-stars, the European names of which are, according to table (7) α Hydrae, π Scorpii, β Aquarii and η Tauri, are slight, their rightascensions increase for a long period yearly by about 3,^s2 or 0,8 minutes in arc and about 4000 years ago, in the time of the emperor Yao, they were 0,8 · 4000 = 3200′ or 53° less than at present. Thus we have:

Table (8)

	Chinese names		European names	Rightascension
	at the time of Yao	at present		1858 A.D.	at the time of Yao $A$	of the Sun $B$	$A-B$
Sign of spring	niao	sing	α Hydrae	140°	87°	0°	87°
Sign of„ summer	ho	fang	π Scorpii	237	184	90	94
Sign of„ autumn		hiu	β Aquarii	321	268	180	88
Sign of„ winter		mao	η Tauri	55	2	270	92

The difference $A-B$, calculated for Yao's time according to modern astronomical tables being nearly equal to 90 degrees, proves the truth of the statement in Shu-King and that the Moon-stars were already established and applied by the Chinese about 4000 years ago, in order to determine the seasons.

As the Moon's orbit is inclined to the ecliptic only 5°, the Moon-stars determining the moon's course and position, are all not far from the ecliptic, that is, their latitude is small and the moon's courses during different lunations never deviate much from the ecliptic andfrom each other. Nevertheless Chinese astronomers distinguish 8 different orbits of the moon, because from one Newmoon, with which the moon's course always commences, to the next Newmoon the place of the Sun among the stars, where the New moon occurs, is advanced from West to East about 29 degrees and the Moon, though passing during every lunation near the same 28 Moon-stars, begins its course in the neighbourhood of another Moon-star, than a month ago and passes the Moon-stars, when in other phases.