打開天窗說天文

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1989 / 3月

文‧謝淑芬 圖‧陳品君


中國的天文之窗開啟得雖早,可惜這扇窗卻總是半遮半掩,未見有更深入的研究。而西方天文學在短短三、四百年內一日千里,終於進入太空,令我們瞠乎其後。

我們何時才能「打開天窗」,馳聘星際?


中國很早就有天文觀測的紀錄,以研究太陽聞名於世的美籍科學家海爾博士,在其著作「宇宙的深淵」中寫著:「中國古人對太陽黑子的觀測,超前西方二千年,且歷代記載不絕,精確可信。」

除了太陽黑子之外,如日蝕、月蝕、流星雨、超新星爆炸,甚至每七十六年拜訪地球一次的哈雷彗星周期等,在中國的天文紀錄中,皆歷歷可尋。

中國古代的天文觀測之所以能持續進行,而不像西方被基督教教義「上帝所造的天是完美無缺」的觀念所阻擾,是有一套政治哲學的強烈支持。

天垂象,見吉凶

中國古人認為,天是具有人格、有意志且能行賞罰的人類主宰,故而「天垂象,見吉凶」——天所示的任何異象,都是對人間的警告,自命為「天之子」的帝王,必須密切注意上天的一舉一動,做為施政參考。因此歷代都設立專司觀測天文的機構和官員,將觀測結果隨時呈報朝廷,並按時送交史官記錄,正史中「天文志」、「五行志」和「律曆志」,就是天文的觀測紀錄。

官方的支持,使中國的天文學得以平穩而持續地發展,累積出足可傲人的成就。

「中國之科學與文明」的作者李約瑟曾提到,除了天文紀錄,中國對世界天文學還有天文座標法、儀器以及「開放」的宇宙觀等貢獻。

官方支持,利害參半

觀測星辰,先要設立座標以示其位置,早期希臘用的是黃道座標法,阿拉伯用經緯度法,中國則採取赤道座標法。據傳戰國(西元前四世紀)石申製作的「石氏星表」,即以此法標示,這種方法精確而簡便,為現代天文學沿用。

為了觀測天空,中國天文學家乃成為製作觀測儀器的高手。例如,我們耳熟能詳的張衡,他的科學傑作「渾天儀」,在球面上刻有南北極、恆顯圈、恆隱圈、黃道、赤道、廿四節氣、廿八星宿及赤道南北一百多個星座等,並以流水為動力使它自己轉動,轉速控制得與天球的自轉相應。它反映我國古代先進的天文學水準,也顯示出當時高超的機械技術。

元朝郭守敬的銅製渾天儀更精美與實用,他簡化歷代渾天儀的結構(因稱簡儀),不僅使用方便、提高精確度,且開創現代望遠鏡的架筒法,現仍存於南京紫金山天文台。

只可惜,凡事「利害參半」。中國固然有官方的支持,早期在天文觀測、儀器製造方面領先其他國家,但也因泛政治之影響,而無法朝更高深的理論研究,發展成一套有系統的科學。

人文思想影響科學研究

舉例說來,我國早在戰國時期已經能推算出日蝕、月蝕的日期,但長久以來這類「異象」,常被用來象徵皇帝的德行有缺,要「減膳」、「撤樂」(節制飲食與享樂),或赦免罪犯,以補過失。

同樣地,我國天文學家觀察到五大行星的運行規律及顏色、特性,後人卻將這些成果引申為陰陽五行說,以解釋歷史與世事的興衰趨勢。

「在所謂『天人感應』思想影響之下,中國的天文觀測始終擺脫不了迷信以及占星色彩」,清大歷史所副教授黃一農解釋,我國的天文官觀測到異象,往往附會政治或解釋人事,而少探究客觀的真理。

從中國自成系統的星座與星名,可以更清楚看出這種「天人感應」思想的影響。

中國的星名,雖然有一部分如西方取材自神話傳說,像牛郎、織女;有些則取其造型和生活器具相似而命名,如營室(房子)、壁(牆壁)、畢(捕兔子的小網)、北斗(盛酒的器物)等。

另一部分星名,很明顯地象徵社會結構,把人間的階級、倫理反映於天上,例如帝、太子、庶子、後宮、上將等,它們的位置也一如塵世間的井然有序:天帝星坐鎮中央不動,皇族、親信大臣在附近圍繞皇帝旋轉。這些星星若有異變,顯示與之相對應的人必有災異禍福。後世再將每顆星星賦予性情,就發展出紫微斗數,來推算人的運命。

觀星?占星?

流風及於民間,從稗官野史、小說叢談之中,都很容易發現例子。「水滸傳」的一百零八條好漢,就是天上的卅六顆天罡星和七十二顆地煞星,因為亂世混濁而下凡替天行道。

神話軼聞固然平添不少趣味,卻不無負面影響。「直到現在,太空梭已在宇宙穿梭,部分國內民眾仍將『觀星』和『占星』混為一談」,私人文山天文台長陳正鵬就不時接到民眾找他占卜、算命的電話。他無奈地表示,小說「三國演義」中那個手持八卦、夜觀天象,就能談笑退敵的諸葛亮,形象早已深植國人心中。

「市面書店到處充斥著中西占星、算命的書籍,而大學生交友,見面就先報自己的星座,卻不知那個星座在天空的形狀、位置、出現的季節」,中央研究院地球科學研究所副所長李太楓認為,國人對天文的興趣雖濃厚,但知識淺薄。

「原因在於天文教育沒做好」,李太楓表示,雖然中、小學的自然教科書中都有天文課程,但「教育人員素質不齊,資訊雜亂,以致有些本身未受專業訓練的教育人員,甚至將似是而非的假科學如星相、命運、不明飛行體等,夾雜在天文課程中。」

排除迷信,加強天文教育

「目前國內沒有正式的天文科系來培養師資」,黃一農道出推行天文教育的困難,去年他在清華大學開通識教育課程「天文與宇宙」,預選人數多達三百人,卻只能讓一百人選修。「師資不夠,設備也不足」,黃一農說,結果還是得勞動數位助教輪流排班,用全校唯一的高倍望遠鏡教學生觀測天象。

省立台北師範實小的自然老師于瑞珠也坦率地表示,她在大學畢業以前從未碰過望遠鏡,一直到教書後,才去圓山天文台教師研習營受訓。「一般人提到『天文』,不是神秘兮兮,就是一副嚴肅、敬畏的表情」,她說,要釐清這些觀念並不難,她就常利用神話故事編成生動活潑的劇本,配合星象儀教學,以引起學生的興趣,灌輸他們正確的天文知識。

「一個國家的天文發展,往往比經濟發展落後至少二、三十年」,李太楓認為,我國近代屢遭戰亂,政府播遷來台後百廢待舉,使我國天文研究呈現斷層,以致許多我們覺得毫不起眼的國家,天文發展都超過我國。

雖然如此,想急起直追也並非不可能。他以日本為例,日本在六十年代經濟起飛,廿年後,才開始在天文研究上嶄露頭角,但去年的超新星爆炸研究,日本的微中子偵測結果為全球矚目。而日本的業餘天文觀測人口密度也居世界之首。

重拾傳統,急起直追

「老祖宗留給我們一筆豐富的遺產」,黃一農認為,重拾傳統、連結現代,全力發展天文科學研究,是我們可以努力的方向。

黃一農本身就是一個好例子。他讀清大物理系時,對天文觀測產生興趣,出國後改攻天文物理,而在研究超新星時發現中國的天文記錄成就,然「外國天文學者不懂中文,我國歷史學者則大多未受過天文訓練,常曲解或忽略了這部分」,回國後,他開始著手整理這些歷史,並與美國海軍噴射推進實驗室的天文研究人員互相支援。目前他已利用電腦,抓出不少古人為了政治目的而造的「假天象」。

西方的天文水準雖曾受宗教束縛,但自從十七世紀哥白尼提出「日心地動」說(地球繞著太陽旋轉),及伽利略發明望遠鏡實測天文,打破教會的禁制之後,牛頓進一步用「萬有引力」定律解釋宇宙、日月、星辰的運行動力。後人更結合物理與天文(天文物理學),探求宇宙的本質。這種求真求實的精神,促使西方的天文學在短短三、四百年內一日千里,終於進入太空,令我們瞠乎其後。

看來,在即將邁入廿一世紀的今天,應該是我們打開「天窗」,延伸無限視野的時候了。

〔圖片說明〕

P.42

天空繁星點點,能否令人想一探究竟?圖為北美洲星雲。(陳培溺寣^

P.43

堯帝時掌管天文的官吏羲和,用簡單的工具觀測日影,制定農時。

P.45

西方星座圖,為一六四五年波蘭天文學家賀威利歐斯所繪。(陳正鵬提供)

P.44

中國古星圖,約繪於一七○○年左右。(陳正鵬提供)

P.46

郭守敬所製的渾天儀,全為精銅打造,又稱「簡儀」。(陳俊榕提供)

P.47

天文觀測教育可培養認真求知的科學精神。

P.47

台北市立圓山天文台的星象館常令小朋友留連忘返。

相關文章

近期文章

EN

Chinese Astronomy--Looking Back……Looking Up?

Daisy Shieh /photos courtesy of P. J. Chen /tr. by Phil Newell

Although the window of Chinese astronomy was early opened, it was half blocked. Rarely was deeper research conducted. And in a brief 300- to 400-year period, Western astronomy made strides, finally entering outer space and leaving us behind. When will we open the window and run wild through the heavens?


China has had astronomical records from very early on. The scholar George Hale wrote: "The observation of sunspots by Chinese preceded that of the West by 2000 years, and moreover accurate and reliable records were kept continuously by successive generations." Solar and lunar eclipses, meteor showers, the explosion of supernovas, and even Halley's Comet can all be found in Chinese astronomical records.

Unlike the West, where the Christian doctrine that "The heavens created by God are perfect," Chinese astronomy was able to continue uninterrupted with strong political support. Early Chinese believed the heavens revealed portents of good or bad fortune, and the Emperor, called "The Son of Heaven," had to refer closely to the motions of the heavenly bodies in governing. Because of this successive generations all established agencies and officials for astronomical observation, whose results were reported to the throne and delivered to the historiographer.

Joseph Needham, author of Science and Civilization in China, points out that the Chinese also pioneered in astronomical coordinates, instruments, and an "open" view of the universe.

To observe the heavenly bodies requires a coordinate system for identifying locations. The early Greeks used the zodiac method, while the Arabs used longitude and latitude. Chinese developed the equatorial method, used in the Warring States era (4th century B.C.) work, Star Charts of the Scholar Shih. Accurate and convenient, the method is still used to today.

Chinese astronomers also became excellent designers of instruments, including the first armillary sphere. Powered by water, it automatically rotated to match the rotation of the earth. It reveals not only the high level of astronomy, but also superior machinery techniques, of early China. A brass armillary developed by Kuo Shou-ching in the Yuan dynasty (1271-1368) simplified the earlier models and improved accuracy; it can be seen today at the Tse-chin Mountain observatory in Nanking.

Unhappily, because of politicization, there was no way to move further toward theoretical research to develop a systematic science.

For example, astronomers could calculate the lunar and solar eclipses as early as the Warring States period, but these "oddities" continued to be interpreted not scientifically, but as symbols that the Emperor lacked in moral propriety, that there was a need to cut back feasting and festing, or that prisoners be amnestied as a benevolent gesture to compensate for the emperor's failures.

"Given the influence of the thinking that 'man and the heavens each reflect the other,' Chinese astronomical observation could never escape superstition," explains Hwang Yi-nung, associate professor of History at Tsing Hwa University. When official astronomers witnessed an unusual celestial event, they would attach some forced political meaning to it, and rarely explored for the objective truth.

The connection between man and heaven can be seen in the names Chinese give to heavenly bodies. While some borrow names from myths or legends, many take the names of common items of daily life: "house," "wall," "rabbit trap". . . . Even more revealing are names reflecting status differences on earth: "emperor," "crown prince," "general." Moreover, their locations reflected their status: the "Emperor of heaven" star sat unmoving in the center, while "family" and "close advisors" bodies circled round it.

Examples abound from unofficial histories or popular tales, revealing the prevalence of the connection of the heavens to man's fate for the common man. In The Water Margin, for example, the 108 heroes are personifications of the 36 Tienkang and the 72 Tisha stars, dispatched to earth to do righteous deeds in a time of troubles and chaos.

Myths and anecdotes are fascinating, but they may have negative side effects. Daniel J. P. Chen of the Private Wen-shan Astronomical Observatory says, "Right up to now some people still confuse 'observing the stars' and 'reading the stars.'"

Li Tai-feng, associate director of the Earth Sciences Research Institute at the Academia Sinica, argues that while interest in the stars and astrology is high, real scientific knowledge about their positions, shapes, and times is lacking. Li says that although middle and primary school textbooks include astronomy, some teachers are inadequately trained, data is disorganized, and sometimes even pseudosciences like fortune telling are mixed into the astronomy curriculum.

"The development of astronomy in a country often lags behind economic development by 20 or 30 years," notes Li. With war, chaos, and the moving of the government to Taiwan, astronomy work was interrupted and developments have passed China by. However, the example of Japan, which was a focus of global attention for results on last year's supernova explosion (and which leads the world in the concentration of amateur astronomers), is encouraging.

Hwang Yi-nung says, "Our ancestors have left a rich heritage," which can be linked with the present. Hwang is a living example: he became interested in astronomy while studying physics at National Tsing Hwa University, and began studying astrophysics abroad. While researching supernovas he discovered the accomplishments recorded in Chinese histories. Since returning to the ROC he has begun putting together historical data, and has used computers to discover politically motivated "false phenomena."

The development of the scientific, experimental outlook in Europe and the discoveries of Copernicus, Galileo, and Newton led to the West's overtaking of China in astronomy. Now, as we approach the 21st century, we can open the window all the way and extend our perspectives to encompass the boundless universe.

[Picture Caption]

The official in charge of astronomy for the Emperor Yao, Hsi Ho, used simple tools to work out the shadows of the sun, and established the lunar calender.

Space is rich in stars; does it make people think of finding its limit? The photo is of the North American Nebula. (photo by P. K. Chen)

A Western chart of the zodiac, done by the Polish astronomer Hevelius in 1645. (photo courtesy of Daniel J. P. Chen)

This ancient Chinese map of the stars was done in about 1700. (photo courtesy of Daniel J. P. Chen)

The armillary made by Kuo Shou-ching was made entirely of refined copper . (photo by Chen Chun-jung)

Education in mapping out astronomy can cultivate an earnest thirst for k nowledge and scientific spirit.

The Taipei City Astronomical Observatory's Planetarium often makes littl e visitors linger and forget to go home.

 

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