Comet, Revised Read online

  Our admiration for the Mawangdui silk is further enhanced when we consider the depictions themselves, which are at least roughly consistent, in a few bold strokes, with modern photographs of the comets. These observers drew what they saw. We have only to compare these images with a European woodcut of the Comet of 1528 (this page) to appreciate their sobriety: no dragons; no devils; no implements of torture. Just comets.

  In surveying the long-standing Chinese absorption with comets, we are reminded of another area in which the Chinese led the way, the invention of fireworks. Might the ancient Chinese have devised skyrockets to adorn the heavens during the long and tedious intervals between comets? Even if rockets and comets were not connected then, they certainly are today (Chapters 6 and 18).

  The ancient Chinese assembled a large, accurate, and detailed body of data on comets. Their catalogues list, for hundreds of apparitions, many of the following pieces of information—a date, the kind of comet, the constellation in which it was first seen, its subsequent motion, its color and apparent length, and how long before it disappeared. Sometimes day-by-day changes in the length of the comet’s tail are recorded. But for all this, they never had an inkling of what comets really were. This was to be wholly an achievement of the West, although it was a long time in coming. Western cometary astronomy prior to the Renaissance is a chronicle of occasional episodes of lucidity—especially in Ionia, Athens, and Rome—punctuating a far longer and more widespread gloom of ignorance, superstition, and delusion.

  The earliest unambiguous references to comets in the West come from what is today Iraq. The few surviving Babylonian fragments remind us of their African and Chinese counterparts. Consider this, from the time of Nebuchadnezzar I, in the twelfth century B.C.:

  When a comet reaches the path of the Sun, Gan-ba will be diminished; an uproar will happen twice …

  Small Arbiter of Human Destiny

  Autumn orchids, luxurious jungle

  Spread life below the hall.

  Green leaves, white blossoms

  A rich and fragrant scent overtakes you.

  From every person comes lovely children.

  Why then, my Lord, such bitter sorrow?

  Autumn orchids, fresh and lush

  Green leaves, purple stem.

  The hall is filled with lovely people.

  Suddenly alone with me, a meaningful glance.

  He came without a word, went without saying goodbye.

  Riding the whirlwind, carrying the cloud banner.

  Grief beyond grief are life’s separations.

  Joy beyond joy are new friends.

  Lotus garments, sweet basil belt

  Suddenly came, hurriedly left.

  His evening lodgings, the gods’ frontier.

  You wait for whom at the clouds’ edge?

  With your lady, bathe in the Pool of Union.

  Dry her hair under the Sun.

  I search the sky for my lovely one—why is he not yet here?

  Face to the wind, indistinct, I lift up my voice in song.

  Peacock-feather canopy, kingfisher-blue flag

  Climb up to the Ninth Heaven, soothe the comet.

  Grasping his long sword, he protects and nurtures the young.

  My Lord alone is fit to bring justice to mankind.

  —CH’Ü YÜAN (340–278 B.C.)

  TRANSLATED BY HEATHER SMITH AND XIE YONG

  Ch’ü Yüan, statesman and one of China’s most beloved ancient poets, committed suicide while in exile by drowning himself in a river. Every May 5, people in China still throw specially prepared rice into the rivers in a symbolic placatory gesture to prevent the fish from devouring his body. In this poem, the comet is both a metaphor for the lost lover and a link to the wise and compassionate god. Many of the seemingly irrelevant images—such as “cloud banner” and “blue flag”—are in reality allusions to the numerous Chinese names for comets.

  The diminishment of Gan-ba is bad news, you can be sure. Occasionally, as in this notice from the same time and place, the auspices are favorable:

  When a star shines and its brilliance is as bright as the light of day, [when] in its shining it takes a tail like a scorpion, it is a fortunate omen, not for the master of the house, but for the whole land.

  A comet bright enough to be seen in the daytime sky must have come very close to the Earth, or the Sun.

  Chinese comet calligraphy. Translation: Broom Star. Calligraphy by Takako Suzuki.

  Record of the World’s Change

  Comets are vile stars. Every time they appear in the south, something happens to wipe out the old and establish the new. Also, when comets appear, whales die. In Sung, Ch’i and later Ch’in times, when a comet appeared in the Constellation of the Big Dipper, all soldiers died in chaos.…

  When a comet appears in the North Star, the emperor is replaced. If it appears in the end of the Big Dipper, everywhere there are uprisings and war continues for several years. If it appears in the bowl of the Dipper, a prince controls the emperor. Gold and gems become worthless. Another explanation: Scoundrels harm nobles. Some leaders appear, causing disturbances. Ministers conspire to rebel against the emperor.…

  When a comet travels north but points south the country has a major calamity. Western neighbors invade and later there are floods. When a comet travels east and points west, there are uprisings in the east.

  … When a comet appears in the Constellation Virgo, some places are flooded and there is severe famine. People eat each other.… If the comet appears in the Constellation Scorpio, there are uprisings, and the emperor in his palace has many worries. The price of rice goes up. People migrate. There is a plague of locusts.

  … When a comet appears in the Constellation Andromeda, there are floods and migrations of people. Many rise up and the country is divided by civil war. When a comet appears in the Constellation Pisces there is first drought and later flooding. Rice is expensive. Domesticated animals die and an epidemic strikes the army.

  When a comet travels into the Constellation Taurus, in the middle of the double month,* blood is shed … dead bodies lie on the ground. Within three years the emperor dies and the country is in chaos. When a comet appears in Orion there are major uprisings. Princes and ministers conspire to become emperor. The emperor has many worries. Everywhere there is disaster by war.…

  When a comet appears in the Constellation Hydra, there is war and some conspire to overthrow the emperor. Fish and salt are expensive. The emperor dies. Rice also becomes expensive. There is no emperor in the country. The people hate life and don’t even want to speak of it.

  —RECORD OF THE WORLD’S CHANGE,

  LI CH’UN FENG, 602–667,

  TRANSLATED BY HEATHER SMITH AND XIE YONG

  The confidence with which these ancient astrological pronouncements are made is striking. There is no hedging of bets, no ambiguity, and no curiosity. We never find a confrontation of two contending hypotheses, much less an appeal to observations to decide the issue. Science had not yet been invented.

  In the works of Diodorus of Sicily (ca. 60–21 B.C.) and Lucius Annaeus Seneca of Rome (ca. 4 B.C.–65) there is indirect evidence—or perhaps it is only hearsay—that the Egyptians and Babylonians had devised some scientific understanding of the comets. Diodorus wrote,

  As a result of their long observations, they [the Egyptians] have prior knowledge of earthquakes and floods, of the rising of comets, and of all things which the ordinary man looks upon as beyond all finding out.

  The annual times of flooding of the Nile Valley were well-known to the ancient Egyptians. From the odd behavior of animals, it is possible —as the modern Chinese have demonstrated—to predict an earthquake early enough to save many lives. But correctly foretelling the apparition of a comet is much more difficult. Maybe someone made a lucky guess.

  As late as 1528, European perceptions of comets had distinct hallucinatory elements. In this woodcut of the comet of that year, a mélange of decapitated heads and miscellaneou
s implements of warfare are depicted. The picture was based on the description of this comet by Ambrose Paré. After Amédée Guillemin, The World of Comets (Paris, 1877).

  A portion of the world’s first cometary atlas, the Mawangdui silk, ca. 300 B.C. Wen wu. “Ma Wang Tui po shu ’T’ien wen ch’i hsiang tsa chan’ nei jung chien shu” and “Ma Wang Tui Han ts’ao po shu chung to hui hsing t’u.” Volume 2, pp. 1–9. (Beijing, Wen wu ch’u pan she, 1978).

  Seneca reports an opinion that the Babylonians believed comets were bodies something like planets. There is no elaboration. We do know that the Egyptians and Babylonians made seminal contributions to mathematics. However, it was in Greece in the fifth century B.C. that curiosity turned away from the supernatural, and first found its world-changing means of expression: science.

  Everything we know of the inventors of this new way of thinking comes to us secondhand. Democritus (born around 460 B.C. and believed to have lived to a very old age) wrote at least seventy works, all of which have been destroyed or lost. Our knowledge of Democritus comes mostly from Aristotle (384–322 B.C.), who held him in high regard and disagreed with virtually everything he had to say. We are told that Democritus believed comets to be produced when one “star” passed near to another. It is unclear whether he held comets to be actual celestial bodies, as the Pythagoreans did. More likely he thought the effect was visual, an optical illusion.

  Aristotle believed he could disprove this hypothesis by noting that in his time Jupiter had come close to a star in the constellation Gemini, and had not produced a comet. But Aristotle did not know that the star was light-years behind the planet, and that only from our perspective were they passing “near” one another. Aristotle’s argument appealed to observation, not myth or conventional wisdom. The debate was scientific.

  Aristotle had other reasons for believing that comets could not live among the planets, reasons again based partly on observation. He framed a supportable scientific hypothesis, which went something like this: The zodiac is the succession of constellations, many named after animals, through which over the months and years the planets, the Sun, and the Moon move. (During daylight, you can’t see what constellation the Sun is in, of course, but with a star map near twilight or dawn you can tell.) The zodiac runs all the way around the sky at an angle to the horizon. For all our ancestors knew, the planets, the Moon, and the Sun might, over the course of a lifetime, wander through every constellation in the sky. Since this does not happen, all the planets must lie very nearly in the same plane. In contrast, comets are observed to travel sometimes within, but sometimes well outside the zodiac. Furthermore, unlike planets, comets change their forms in a few days, before the eyes of the observers. Thus comets could have nothing in common with planets. They must be sublunary, beneath the Moon—that is, within the Earth’s atmosphere. (Aristotle thought the Moon represented the farthest reach of the atmosphere.) The conclusion was clear: Comets were a form of weather. Although there was some debate early on, this view held sway for two thousand years.

  All of Aristotle’s astronomy was predicated on his deep conviction that the heavens were “free from disturbance, change and external influence …” He believed that the Earth was absolutely stationary in space—as if nailed down. The heavens, on the other hand, were whipping around the Earth at the brisk rate of a rotation a day. The bottom of the atmosphere clearly is stationary with the Earth. But the top of the atmosphere must share the sky’s rotation. Now, imagine an exhalation of hot, dry gas from the Earth—perhaps through a fissure, a crevice, or a volcano. That gas will rise and, when reaching the sky, be heated by the Sun and, he thought, burst into flame. But since the burning gas has reached the realm of the heavens, it must now move with the stars and the planets. This was Aristotle’s explanation of the comets. And—given the limitations of the science of his day—it was far from foolish.

  He taught that the aurora borealis and even shooting stars were examples of the same sort—exhalations from the interior of the Earth rising to the stars. Comets survive, he taught, until all the gas had burst into flame. New comets were due to new exhalations. There was thus a balance or steady state between the production and the destruction of visible comets, an idea still central to understanding them. Aristotle held that there are so few comets because most of the flammable vapors outgassed by the Earth were otherwise employed—in producing the continuous band of fire called the Milky Way. In contrast, Democritus had concluded that the Milky Way is composed of an enormous number of stars, so far away that we cannot see them individually—exactly the right answer.

  Underlying Aristotle’s scientific arguments was a quasi-religious doctrine: He was forced to concoct a terrestrial source for the comets, since he had locked them out of his changeless skies, decreeing that no new celestial bodies may be born, and no old ones die. His insistence on the immutability of the heavens was the most influential error in the history of astronomy, contributing to a detour from reality that lasted nearly two millennia. But Aristotle cannot be held fully accountable for the acceptance accorded his opinions by succeeding generations.

  Seneca, born in Cordoba, Spain, to a wealthy and famous family, was a contemporary of Jesus, although the two never met. His brother, though, was an acquaintance of Saint Paul. As a young man, Seneca went to Rome, where he studied grammar, rhetoric, law, and philosophy. He enjoyed a substantial reputation as writer and orator until the year 41, when he was banished to Corsica for sleeping with Caligula’s sister. Considering this emperor’s predilection for cruelty, the punishment was mild. Seneca spent his years of exile writing and studying philosophy and natural science; astronomy was among his pursuits.

  In the year 49, he was recalled to Rome to teach. As a tutor, his success was mixed, his only pupil being the future emperor Nero. When at the age of seventeen Nero was raised to the purple, Seneca became political adviser to the emperor and minister of state. For the next eight years, Seneca and Sextus Afranius Burrus, the commander of the Praetorian Guard, ran the Roman Empire. By all accounts they performed well, fostering fiscal and judicial reforms and somewhat easing the lot of the slaves. But Nero grew more tyrannical, Burrus died—perhaps of foul play—and Seneca’s political power withered. He withdrew from public life, and wrote some of his most celebrated works until, in the year 65, he received an imperial command to commit suicide for his alleged involvement in a conspiracy against the Empire. He died with courage and composure.

  Seneca left works on many subjects, but it is his Natural Questions, written during the last years of his life, that concerns us here. The seventh “book” is entitled “Comets,” and Seneca does the subject considerable justice, taking on Aristotle with some success. He argues that comets could not be atmospheric disturbances: they move with stately regularity and are not dissipated when the wind is blowing. Thus, “I do not think that a comet is just a sudden fire, but that it is among the eternal works of nature.” In refuting Aristotle’s argument that comets cannot be planets since they are not restricted to the zodiac, Seneca asks, faintly echoing the Book of Job:

  Who places one boundary for planets? Who confines divine things in a narrow space? [The planets] … have orbits that are different from one another. Why, then, should there not be other stars which have entered on their own route far removed from them? What reason is there that in some part or other of the sky there should not be a passageway?

  To the objection that stars can be seen through comets, so comets must be incorporeal and cloudlike, Seneca replies correctly that the transparency applies only to the tail, not necessarily to the head.

  One of the most fascinating passages is Seneca’s exposition and critique of the views of one Apollonius of Myndos, an otherwise unknown Greek scholar from the fourth century B.C.:

  … Many comets are planets … a celestial body on its own, like the Sun and the Moon. It has a distinct shape … not limited to a disk, but extended and elongated lengthwise.… A comet cuts through the upper regions of the univer
se and then finally becomes visible when it reaches the lowest point of its orbit.… Comets are many and various, different in size, unlike in color.… Some are bloody, menacing—they carry before them the omen of bloodshed to come. Others diminish and increase their light, just as the other stars [planets] do which are brighter and larger when they descend because they are seen from a closer position, and are smaller and dimmer when they recede because they are withdrawing far away.

  Except for the business of comets as omens, Apollonius’ views—which Seneca shares and extends—seem astonishingly modern.

  In “Comets,” Seneca’s style is so direct that you have no difficulty hearing his voice speaking inside your head. “We can only investigate these things,” he tells you, “and grope in the dark with hypotheses, not with the assurance of discovering the truth, and yet not without hope.” He continues,

  Many things that are unknown to us the people of a coming age will know. Many discoveries are reserved for ages still to come.… Nature does not reveal her mysteries once and for all. We believe we are her initiates, but we are only hanging around the forecourt.

  And the loiterers in the temple forecourt were dwindling. Seneca laments what he saw in his time as a waning of “interest in philosophy. Accordingly, so little is found out from these subjects which the ancients left partially investigated, that many things which were discovered are being forgotten.” For good reason, he surmised a growing intellectual lassitude in his world. His reliance on reason, his willingness to decide between alternatives on the basis of objective evidence, stand in marked contrast to the approach of the next generation—of Lucan (39–65), for example, Seneca’s own nephew, who wrote: “The heavens appeared on fire, flaming torches traversed in all directions the depths of space; a comet, that fearful star which overthrows the powers of the Earth, showed its horrid hair.” Or consider the view of Seneca’s contemporary, the naturalist Pliny the Elder (23/24–79):