From the Ground to the Sky：The Silk Road and Astronomy Exchange

Gong+Likun

The Silk Road was a road of exchange， except commodity trade， it brought different cultures， ideas and technologies. As a worldwide discipline， astronomy had very great achievements in the East and the West. These achievements were exchanged mutually through the Silk Road， promoting each other's development.

"Zodiac" introduced to China for the first time

In our classical literature， the meaning of the word "astronomy" was more than that existed in the form of mathematical sciences which we usually thought. In the era of pre scientific revolution， astronomy had been existing as a discipline including cosmology， view of nature， and view of history， really affecting the destiny of nations and individuals.

As for China， the above influence of view of astronomy permeated the whole Middle Ages， and the lingering influence did not completely dissipated until the 20th century. While in the classical sense， the concept of "astronomy" contained both the almanac part， the mathematical astronomy which we usually thought and a large part of occult. In the previous academic studies， there was a tendency to getting rid of occult in classical astronomy deliberately. However， in recent studies made in more than thirty years， the content of occult was attracting more and more attention of the astronomers. On the one hand， many astronomy knowledge was spread to Eurasia by means of the form of "astrology" and the like， on the other hand， this was a window for us to observe cultural exchange.

Like modern people， many people in Tang Dynasty were crazy about expensive foreign goods and exotic imagination， and "astrology" peddled for various purposes by Buddhist monks wandering up and down the country and warlocks had a market at that time. For example， "Zodiac" often mentioned in entertainment news today was usually thought to be emerged in last one century. But in fact， since Sui and Tang dynasties， from ordinary people to the stratum of scholars took delight in talking about astrology， and the translation of "Leo"， "Cancer" and the like which we are familiar with now appeared in Mahāvaipulya Mahāsamghāta Sūtra and Contributions a Uxetudessur Touen， etc. And， this fashion was not just a flash in the pan， astrologists and scholars were more familiar with Zodiac until Southern Song Dynasty. Han Yu had said in Sanxing Xing that his horoscope was Capricorn， and sympathized by Su Shi after several hundred years. In addition， there were fairly complete Zodiac patterns in tombs of Liao Dynasty unearthed in Xuanhua in the last century.

Foreign experts

making suggestions

Talking of serious issues of exchanges of astronomy technologies， there were a lot of astronomers from Central Asia and South Asia but residing in Tang Empire for a long term. In the 6th to the 10th centuries， the highest astronomical institution in Tang Dynasty， Grand Astrology Administration （it was changed in the course of change and development， for example， it was renamed as "Huntianjian" during the reign of Empress Wu， we will not list the names here） had the responsibilities of compiling calendar， and doing textual research on astronomical phenomena. In the 300 years， when reviewing the persons who had served as officers in Grand Astrology Administration， you will find that many of them are foreign calendarists.

Gautama Siddha， the "foreign expert" was from Gautama family coming to Tang Dynasty from India， whose family had been in charge of revising calendar for Tang Dynasty since early Tang Dynasty. Gautama Siddha himself had translated Navagrahe， which was more accurate than Gihō Calendar and Taien Calendar in some specific algorithms. Father and son of Gautama Siddha also had served as the officer of Grand Astrology Administration， his family was called "Officer Gautama" because it was in charge of official astronomy of Tang Dynasty for a long time.

Exchanges between the

ages was without ceasing

In Song Dynasty， because the government had always treated the power of calendar making as one of the legitimacy sources， the persons who learned astronomy without permission were controlled and punished more stringent （but street augurs related to astrology were beyond the scope of control）. It was also why sometimes astronomical knowledge spreading out was much more difficult than introducing.

China under the reign of Mongolia， some changes occurred in this state. It is worth mentioning that the equatorial armillary sphere invented by Guo Shoujing with the equator as the coordinate system was exported to Arab， and it was likely under the influence of Arab that Europeans began to notice this important invention of equatorial armillary sphere. Joseph Needham， a British historian believed that it was likely due to the influence of China that Tycho abandoned Grace-Iran coordinate system in the 16th century and adopted the coordinate system commonly used by Chinese.