128 astronomy: Asia and the Pacific understanding of astrology Kings, in fact, restricted such study to scholars under royal employment, in hopes of maintaining a sure hold on power that was often secured through accurate predictions Into medieval times ordinary citizens were punished for possessing or using objects associated with the measurement of celestial bodies or with divination based on such measurements The importance ascribed to the study of astronomy is reflected in the fact that the Chinese recorded a number of observations before either the Greeks or the Babylonians In general, the ancient Chinese classified astronomical events into two categories: predictable and unpredictable Predictable events included the shifting of the phases of the moon and the rotation of the constellations around the North Star Unpredictable events of particular note included the wandering of the planets (whose orbits were long undetermined in geometric terms), the appearance of comets, and instances of sunspots, which were especially observable when dust storms in northern China screened the sun’s glare A great deal of attention was paid to these unpredictable events, which wise men, particularly those in the service of rulers, interpreted in order to extract cosmic meaning Knowledge regarding predictable events, then, was valued largely for its providing the frame of reference against which unpredictable events occurred The origins of an imperial almanac, which served as a register of these predictable events, are so ancient as to be obscure The almanac delineated the annual astronomical cycle, including the lengths of the months (which were based on the phases of the moon and thus varied from year to year) and the dates of the equinoxes (the two times of the year at which the sun crosses the equator and day and night are of relatively equal length) and solstices (the times of year when the sun is at the greatest distance from the equator and the day is either at its shortest or at its longest, depending on the season) The year began at the winter solstice, when the yang force—a Chinese conception associated with warmth, among other qualities—was at its nadir Since the winter solstice often proved to be a cloudy day, its date was calculated based on that of the summer solstice, which was determined through the measurement of the shadow of an 8-foot stone pillar The length of the year was estimated to be 366 days until the fourth century b.c.e., when the figure was revised to 365¼ days; further corrections were made continually thereafter According to legend, basic star charts were first compiled sometime before 1000 b.c.e by a shaman named Xian, who identified the Big Dipper, among other constellations The revolution and rotation of the Big Dipper around the North Star, rather than the movement of the sun, provided the basis for many Chinese astronomical computations Records still exist of the star charts compiled in the fourth century b.c.e by the early astronomical observers Shi Shen and Gan De—whereas charts compiled by Timocharis (ca 320–260 b.c.e.), of Greece, have never been found Much later, in the fift h century c.e., Qian Lezhi incorporated the findings of his Covered jar, from the second to first century b.c.e., China; the scene is of a blue beast (the star Sirius) with bared fangs lunging at a mounted archer (the adjoining constellation, Bow) (Copyright the Metropolitan Museum of Art) three regional predecessors into a single chart, coding their findings with the colors white, red, and black Comets, eclipses, and supernovae (explosions of stars) were seen as especially momentous astronomical occurrences Records of comets are more extensive in China than in anywhere else in the ancient world, and these records provided the original basis for determining the orbit of Halley’s comet, which was sighted in China first, in 240 b.c.e Records of eclipses extend back even further in time, as inscriptions were found on oracle bones— animal bones that were used for divination—dating back to the Shang Dynasty, which ended around 1045 b.c.e Thus, Chinese records predate Babylonian ones by some seven centuries Starting in the third century b.c.e eclipses were carefully registered Supernovae, which are stellar explosions that can make distant stars visible to the naked eye for the first time, were referred to as inexplicable new stars or stranger stars The Chinese made a number of advances in the design of astronomical equipment The Han Dynasty, which lasted from the second century b.c.e to the second century c.e., witnessed the invention of a star-mapping tool called the armillary sphere, a fi xed set of rings demarcating the sectors of the sky The ring representing the skyward extension of the