Lost Discoveries: The Ancient Roots of Modern Science--from the Babylonians to the Maya - Softcover

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Dick Teresi is the author or coauthor of several books about science and technology, including The God Particle. He is cofounder of Omni magazine and has written for Discover, The New York Times Magazine, and The Atlantic Monthly, and is a frequent reviewer and essayist for The New York Times Book Review. He lives in Amherst, Massachusetts.

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from Chapter Three

Astronomy: Sky Watchers and More

China

Chinese astronomy resembles most other premodern sky technologies in that it was driven by divination. Yet Chinese astronomy differed from all others. It was run solely by a government bureaucracy and based on a worldview that said the ruler was "emperor under all heaven" -- a divine appointment. Yet the connection between celestial events and human fate was perhaps even more profound. The link was not just between heavenly deities and the emperor; the earth, the emperor, and the entire cosmos were bound together in one gigantic entity, a superorganism in which the five elements, or "phases" -- fire, air, wood, earth, and water -- were in constant interaction as they sought their affinities with one another.

Yet in China as elsewhere, portent astrology called for careful and regular observations of celestial events. The cosmic importance of every omen in the sky demanded that its results be noted down in detail. As a consequence, the Chinese possess the longest unbroken run of astronomical records in the world, observations of considerable importance to modern astronomers, whose research requires data about long-term celestial events.

China developed astronomy very early in its history. Evidence goes back five thousand years. The ancients wrote stars-laden texts in many forms -- on wine jugs, tortoise shells, and silk. The earliest records from archaeological sites in Qinghai Province consist of ceramic fragments on which are painted images of rayed sun disks and moon crescents. A piece of bone found to be thirty-five hundred years old contains writing showing that the Chinese already knew the length of the year to be 3651Ž4 days. There is evidence of star observation from before the twenty-first century B.C.186

The first recorded astronomical inscriptions date from the sixteenth to nineteenth centuries B.C. in the Shang kingdom of Henan Province. These artifacts are examples of an astronomical-divination system, technically called scapulimancy, a technique going back to Neolithic times. Selecting an ox or deer shoulder blade (scapula) or a tortoise shell, the diviners then dried, polished, and drilled the material with holes. They inserted a hot metal brand into one hole and examined the pattern of resulting cracks in the bone or shell. The diviner noted both the prognostication and later results on the cracked material.

The oracle bones' existence was lost to the modern world until 1899, when a scholar from Peking became ill and sent his valet to a drugshop for medicines. One ingredient in the potion the pharmacist sent him was labeled "dragon's bones." The scholar realized it was bone chips with words inscribed on them in ancient Chinese -- oracle bones.

During the following decades the bones were traced to a field near An-yang, around three hundred miles southwest of Beijing. During the 1920s and '30s, some twenty-five thousand oracle bones were excavated there, from what may have been a palace archive. At least 135,000 more pieces have been excavated since, forming a treasury of information going back to Shang times. This vast library recorded on the bone texts has enabled modern historians of astronomy to backtrack regularly occurring celestial events with computers to match sky phenomena inscribed millennia ago.

Recently, NASA astronomers used fourteenth-century B.C. oracle bones to help determine how much the earth's rotation is slowing down. Based on analysis of the tortoiseshell inscriptions, Kevin Pang and his colleagues at the Jet Propulsion Laboratory at Pasadena reported they had fixed the exact date and path of a solar eclipse seen in China in 1302 B.C. That, in turn, led them to calculate that the length of each day was 47Ž1,000 of a second shorter in 1302 B.C. than it is today.

A cache of five thousand pieces of oracle bones excavated in An-yang in 1972 yielded a series of divinations of sky events. The Chinese astronomical historian Zhang Peiyu found that six dates recorded in the inscriptions matched perfectly with a series of solar eclipses visible from the Henan area in the twelfth century B.C., half a millennium earlier than records of such events obtained from Babylonia or Egypt. Other Shang bones yielded inscriptions of lunar eclipses.

A reconstruction of another bone recording from around the same time revealed the observation of a supernova. The supernova inscription, perhaps the most ancient extant record of a nova sighting, says, in part, "On the seventh day of the month...a great new star appeared in company with Antares." The Chinese called these supernovas "guest stars." Thus the Chinese knew well what they were observing when, in June 1054 (A.D.), a star in the constellation Taurus blew. Chinese sky watchers reported it to be as bright as Venus, apparent during daylight, and visible for twenty-three days. The remnant of this explosion can be seen today and is called the Crab Nebula. (The Greeks have no record of the supernova.) Experts today have compiled detailed descriptions of supernova explosions that coincide with contemporary X-ray and radio sources.

In the Greek-influenced West, the sun and heavens were supposed to be immaculate. But Chinese astronomers saw spots on the sun. The earliest surviving record of a sunspot observation is by the astronomer Kan Te in the fourth century B.C. Kan Te assumed that these spots were eclipses that began at the center of the sun and spread outward. Although he was wrong, he recognized the spots for what they were -- solar phenomena.

The next documentation of sunspots was in 165 B.C., when it was reported the Chinese character wang appeared in the sun -- shaped like a cross with a bar across the top and bottom. It is accepted as the world's earliest precisely dated sunspot. The West's earliest reference to sunspots is Einhard's Life of Charlemagne, around A.D. 807. Joseph Needham found 112 instances of sunspots recorded in Chinese histories between 28 B.C. and A.D. 1638. In other Chinese books he found hundreds more notices, "but no one has had time or stamina to collect them into a body," comments sinologist Robert Temple. Nonetheless, the sunspot records constitute the oldest continuous series of such observations. And again, these are of great use to modern astronomers. Sunspot cycles, for instance, affect the earth's ionosphere and weather (magnetic storms are related to sunspots). Analyzing available records, Japanese astronomer Shigeru Kanda reports he has detected a 975-year sunspot cycle. If so, it may have significant implications for weather cycles.

The Chinese were also careful observers of comets. They computed the approximate orbits of about forty comet trajectories with such precision that many of their trajectories could be drawn on star charts simply from reading ancient texts. They were interested in the precise position and direction of the tail of each comet.

In the year 240 B.C., astronomers officially documented the appearance of a comet today known as Halley's. Another comet recorded in 467 B.C. is also thought to be Halley's. In the 600s A.D., they observed that comets shine by reflected light like the moon. They noted that comet tails always pointed away from the sun, suggesting this phenomenon was the result of a solar "energy." Today it's known that this cometic tail direction is caused by the force of "solar wind," the sun's radiation. It wasn't much of a stretch, says Temple, for the Chinese to formulate the idea of solar wind. It is congenial with their cosmological assumptions, Chinese literature being filled with references to the ch'i of the sun's radiation. Ch'i, translated as something like the "emanative or radiative force," comes from the sun. To Chinese astronomers it would have been obvious that the sun's ch'i was strong enough to blow the tails...