Once again, Chinese astronomers have started making observations on the comets hundreds of years ago. In Chun Qiu (Spring and Autumn Annals), it stated that in the autumn of 613 B.C., a comet(western astronomers call it Halley's Comet) was seen travelling into the Great Dipper. The Chinese astronomers have continued to keep record on the appearance of Halley's Comets on 31 occasions for the next 2500 years. The most detailed description of the Halley's comet was written in History of the Han Dynasty in 12 B.C.. It stated "On the 12th month in the first year of the reigh of Yayuao of the Yuan Dynasty a star first appeared in the Dongjing constellation, then travelled past Wuzhuhou and the region north of Heshu.It was seen successively in Xuanyuan and enclosure Taiwei and was six degrees behind the sun when it appeared in the east in the morning. On the 13th it was seen in the west after sunset. Its tail was again in the enclosure Ziwei. It headed south at the same longitudes at tajiao [Arcturus] and Nieti [Muphrid]. It slowed downwhen it reachedthe Enclosure Tianshi with itz tail in the center of that group of stars. Ten days later it flew westward and after 56 days it disappearded along with Canglong of the ecliptic." The passage abovegave lively descriptions of the route, apparent velocity and the time of appearance and disappearance of the gigantic comet.