雙語科技百科(天文) 第16期:《靈憲》
A monumental astronomic works，Ling Xian，translated as Mystical Laws is a distillation of the years of practice and theoretical research by Zhang Heng，a famous astronomer of the Eastern Han ing with such topics as the formation and structure of the heaven and earth and the cosmicevolvement as well as the nature and movement of celestial bodies，the book pro-moted the level of ancient China’s astronomical level to a new high and cast a pro-found impact on the following generations.
《靈憲》是東漢著名天文學家張衡積多年的實踐與理論研究寫成的一部天文鉅著。該書全面闡述了天地的生成、宇宙的演化、天地的結構、日月星辰的本質及其運動等諸多重大問題，將中國古代的天文學水平提升到了一個新階段，並對後世產生了深遠的影響。The astronomical achievements of Lang Xian are as follows:
《靈憲》的天文學成就如下:
First, Ling Xian discusses the origin and structure of the cosmos. In terms of the formation of the heaven and earth，Ling Xian believes that the heaven earth，and all the other things have their origins in primitive and chaotic yuanqi(vi-tality) further holds that，instead of staying permanently unchanged，the struc-ture of the cosmos is constantly developing. These views，basically, are similar to modern theories on the evolution of the cosmos.
第一，論述了宇宙的起源和宇宙的結構。關於天地的生成問題，《靈憲》認爲天地萬物是從原始的渾沌未分的元氣發展來的。這種天體演化思想，是從物質運動的本身來說明宇宙的形成，認爲宇宙結構不是亙古不變的，而是不斷髮展變化的。這些觀點，與現代宇宙演化學說在基本原理上是相通的。Second，based on the theory of sphere heavens，the book scientifically elabo-rates on the lunar eclipse.、。。explanation of the phenomenon，Zhang Heng wrote in the book“The moon itself is not luminescent, but rather reflecting the sunlight. The part of the moon where the sunlight fails to reach will not give out light. If the moon into the shadow of the earth，a lunar eclipse occurs.
第二，在渾天說的基礎上，科學地闡述了月食的原因。張衡在《靈憲》中寫道:“月光生於日之所照;魄生於日之所蔽。當日則光盈，就日則光盡也。”(大意爲:月亮本身是不發光的，而是太陽光照射到月亮上，月亮才折射出光，太陽光照不到的地方則出現虧缺。如果月亮進人地影，就會發生“月食”。)Third，in relation of the finity and infinity of the cosmos，Zhang Heng com-pared the heaven to an eggshell，and the earth to the egg g Heng，however , did not believe the eggshell to be the boundary of the viewed the cosmos that people could see with the naked eye as limited while the part that could not be seen as infinite.
第三，宇宙的有限性和無限性。張衡把天比作一個雞蛋殼，把地比作蛋殼中的雞蛋黃，但他並不認爲硬殼是宇宙的邊界。張衡認爲，人們目之所及的宇宙世界是有限的，但在人們目之所及之外的宇宙世界則是無限的。Fourth，Zhang recorded his measurement of both the sun and the moon’s an-gular diameter,which is 1 /736 of the celestial sphere，or rather 29度21(or 29度21)，an absolute difference of 20from the modern average value of 31度5(or 31度5)idering the scientific level and observatory conditions of over 2000 years ago，the number is fairly precise.
第四，張衡實測出日、月的角直徑是整個周天的1/736，即29021，這與近代天文測量所得的日和月的平均角直徑值3105，相比，絕對誤差僅有2。由於2000多年前的科學技術水平及觀測條件，這個數值可以說是相當精確的。Fifth，based on his careful observation of the celestial bodies，Zhang Heng sorted out the various star charts made by his predecessors and re-established a new chart, recording the position of over 3,000 stars.
第五，張衡在認真觀察天體的基礎上，對前人留傳下來的好幾種星表作了整理、彙總，建立了恆星多達三千的新星表。The last but not the least, concerning the movement of the five planets，Zhang worte:‘The sun,the moon and the flue planets all move in-between the heaven and earth rather than on the wall of the celestial sphere. Moreover the seven ce-lestial bodies move at different speeds.’
第六，關於五星的運動問題，張衡提出:日、月、五星是在天地之間運行，而非在天球壁上運行。並且，這七個天體運動的速度各不相同。Ling Xian,is one of the most outstanding astronomic works in the history of ancient Chinese astronomy，represents a milestone in the development of Chinese astronomy. Its importance in the astronomical history is not lessened at all by its mistakes and shortcomings.
《靈憲》是中國古代天文學史上最傑出的天文學著作之一，也是中國天文學發展的一個里程碑。雖然其中還有一些錯誤和不足，但在天文學史上、的意義並不因此而遜色。
