The Great Christ Comet (22 page)

From these surviving Bab­ylo­nian records, we can get a good idea of what typical Bab­ylo­nian cometary records looked like. Stephenson deduces from the Bab­ylo­nian evidence that the Bab­ylo­nian astronomers included entries concerning comets at particular stages of a comet's apparition—at the first observation of the comet, at its heliacal setting, at its heliacal rising, whenever the comet (i.e., coma) became stationary relative to the fixed stars and constellations, and when the comet last appeared.
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Each entry after the initial one made a summary reference back to a previous entry concerning the comet.
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The Bab­ylonians commented on the comet's locations within the sky generally (east, west, north, equatorial zone, south) and specifically within the constellations, and
the direction and length of the tail.
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Moreover, Stephenson points out that they obviously knew that the very same comet could be observed both prior to conjunction with the Sun and after it.
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Interestingly, the surviving Bab­ylo­nian cometary records seem to reflect a bias toward comets that are located within the zodiac (the band of sky through which the Sun, Moon, and planets seem to traverse).

Strangely, Diodorus Siculus,
Bibliotheca
15.50.3, reports that the Bab­ylonians were believed to be able to predict cometary apparitions accurately on the basis that comets complete cycles through age-long movements in appointed courses. Hermann Hunger et al. highlight that the logical deduction of what Diodorus Siculus claims is that the Babylonians compiled extensive tables of data regarding comets, as they did for eclipses.
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It is not unlikely that there were, included in these records, cometary observations dating back as far as the eighth century BC.

As we have already seen, Bab­ylo­nian records of Halley's Comet in 164 BC and 87 BC have survived, the latter only in fragmentary form. Concerning the Halley's apparition of 12 BC, Hunger et al. comment that, although the Bab­ylo­nian astronomers no doubt analyzed the comet very closely, no trace of their records has survived.
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Chinese Records

A major boon for students of the history of astronomy is the surviving records of celestial phenomena kept in the Far East, particularly in China and Korea. They provide an invaluable collection of cometary observations all the way back to the first millennium BC.

For our purposes, however, the records we have from Korea are few and far between and of questionable reliability, and those from ancient China, largely preserved in a multivolume historical work known as the
Han shu
,
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while more numerous and reliable, are far from complete.

There can be little doubt that the Chinese astronomers at the end of the first century BC observed many, if not most, naked-eye comets. However, a large number of these reports were not available to the writers of the
Han shu
, either because they were not made the subjects of memorials to the emperor and therefore were not formally included in the court register, or because they had been lost in the subsequent period. Of the records of cometary apparitions that
were
available to the historians, they elected to use only certain ones that were in accord with their ideological reading of the larger narrative of the Former Han dynasty. The criteria for inclusion rather than exclusion were not the brightness or coma/tail size, but rather the perceived astrological significance of the comet and especially the usefulness of the apparition in advancing the historian's ideological agenda.
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As John T. Ramsey and A. Lewis Licht put it, “Our extant sources clearly reflect but a small fraction of the records that were once kept by the imperial Astronomical Observatory, and the records that do survive are far less detailed and complete than the accounts from which they were drawn. We should not, therefore, conclude from the absence of a report in the Chinese sources available to us today that the sighting of a given comet
was not necessarily made from China.”
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How Comprehensive Are the Surviving Ancient Records?

Unfortunately, even when we combine all the records for any given ancient period, they fall far short of a comprehensive list of visible comets.

In his study of how many naked-eye cometary apparitions there would ordinarily be each century, Licht calculated that there would be an average of 87.
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Ramsey and Licht wrote about the situation in the first century BC:

To take the first century B.C. as an example, Hasegawa lists 34 naked-eye comets seen during those hundred years, out of which 16 were seen by only the Romans and/or Greeks, 15 by only the Chinese and/or Koreans, and 3 by observers both in the Mediterranean and in the Far East. However, based upon the statistics in Hasegawa's catalogue for recent centuries, for which our records are fullest, there should have been as many as 87 naked-eye comets visible during the first century B.C.
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According to the analysis of Hughes, the rate of naked-eye-observed long-period comets has been rather consistent over the past 2,000 years at approximately 81–99 per century.
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For the period 50 BC to AD 50 we have surviving records of at most one-third of all visible comets.

Consequently, any investigation of ancient comets must bear in mind that relatively few records have been preserved. As Ramsey and Licht highlight, “The vast majority of comets have come and gone without leaving a trace.”
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Ancient Views of Comets

The influential Greek philosopher Aristotle believed that comets were merely meteorological phenomena, the product of the earth's warm exhalations rising to the highest part of the sphere of air and indeed to the border of the sphere of fire, where they ignited. Thereafter they were transported around the region of the upper air.
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Seneca, following the Bab­ylo­nians, had
more sensible ideas concerning comets. He accurately predicted that “one day a human will be able to show the regions in which comets have their orbits, why their course is so far from the other stars, what size they are, and of what they are constituted” (Seneca,
Natural Questions
7.26.1).
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Unfortunately, it was Aristotle's atmospheric view of comets that dominated Western thinking about comets until the modern era.

These “hairy stars,” as the Egyptians and Greeks thought of comets, were widely regarded by the ancients as heralds of important events on Earth.

The Romans, particularly the ruling elite, could assign great significance to the appearance of comets. For example, Suetonius,
Nero
36, relates how Nero, in the middle of the first century AD, responded to a comet during his latter years: “It chanced that a comet had begun to appear on several successive nights, a thing which is commonly believed to portend the death of great rulers. Worried by this, and learning from the astrologer Balbillus that kings usually averted such omens by the death of some distinguished man, thus turning [the omens] from themselves upon the heads of the nobles, he resolved on the death of all the eminent men of the State.”
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Rulers from across the ancient world, from Europe to the Near East to the Far East, were acutely aware of the need to be kept abreast of any strange astronomical phenomena, in particular eclipses and comets, that might augur ill for them, their dynasty, or their kingdom. They also knew that celestial signs, and any unfavorable interpretations of them by court astrologers that might leak out, risked empowering enemies inside and/or outside their realm, because to those eager for change, comets could be important portents of hope.

Even Aristotle and Seneca believed that cometary apparitions were harbingers of disaster.

Because bright comets have orbits that may cut across the ecliptic at any angle and hence are frequently located well away from the zodiac, they often did not fit neatly into the standard Bab­ylo­nian and Greco-Roman system of astrological interpretation focused on the zodiac. A different interpretive approach was therefore called for in the case of comets.

Pliny the Elder (
Natural History
2.22–23) set out principles by which cometary apparitions could be interpreted; by taking note of the comet's appearance, its placement within the sky, and the way in which its tail pointed, one could figure out the nature and geographical location of the doom of which the comet was warning:

It is thought important to take note of the direction in which [the comet] shoots, the star from which it receives its influence, what it looks like, and in what places [in the sky] it shines. If it looks like a flute, it is an omen regarding the art of music; if it appears in the private parts of constellations, it is an omen for immoral behavior; it portends genius and erudition if it forms an equilateral triangle or a rectangular quadrilateral in relation to some of the fixed stars; and it portends poisonings if it appears in the head of either the northern or the southern Serpent.
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Ptolemy held a view similar to Pliny, stating that the shape, the zodiacal constellation in which the coma appeared, the direction of the tails, the timing and duration of the apparition, and the position of the comet
relative to the Sun were important clues for determining the meaning and target audience of a comet.
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From Pliny and Ptolemy we get a good idea how the astrological system of interpretation with regard to comets worked. When one factors in that comets often move around through different parts of the sky, one begins to appreciate the number and complexity of messages that astrologers might divine from them.

Based on what Pliny and Ptolemy wrote, we can set forth a series of questions that astrologers in the Greco-Roman and probably Bab­ylo­nian environment around the turn of the ages would have asked in order to determine a comet's meaning and significance:
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Where in the sky did the comet first appear?

What did the comet as a whole look like? For example, did it seem similar to a beam of wood, a sword, a javelin, a flute, a trumpet, a horn, a torch, a beard, a mane, a goat, a discus, a jar, or a cask? What was its color? Shape? Size? Movement? Brightness?

What did the comet's coma (or head) look like?

In what zodiacal constellations was the comet seen?

Where within constellations did it appear? The private parts of a human constellation figure such as Hercules, Orion, or Andromeda? The head of one of the celestial serpents? Etc.

In what direction did the comet seem to point?

What events in the heavens or on the earth coincided with the comet's appearance? For instance, a comet that occurred at the time of an eclipse or the commencement of a new ruler's reign was liable to be interpreted with reference to that event.

Where in the sky did the comet seem to pause?

How long did the cometary apparition last?

With which stars was the comet in conjunction? How did it relate to established celestial entities like the stars, the planets, the Moon, and the Sun?

What was the position of the comet relative to the Sun? This revealed the beginning of the augured events: if it was to the west, it meant the onset of the prophesied woes was delayed; to the east, it meant the onset was imminent (Ptolemy).

Of course, many of these principles for the interpretation of comets would have been adopted well beyond the circle of astrologers. One did not need to buy into an astrological system of interpretation to conclude that a serpent-shaped comet in a serpentine constellation might be bad news for
a ruler or dynasty, or to believe that a large and bright sword-like comet hanging over a city was an omen of judgment against that city. Josephus, the Jewish historian, made it clear that he believed that a cometary sword standing over Jerusalem in AD 65–66 was a powerful omen auguring the destruction of the city in AD 70.

Although comets were often perceived to be negative omens in the ancient world, on many occasions they were interpreted positively, as we shall see in the following chapter.

Comets in the Bible?

In the Biblical tradition, comets seem to be regarded as capable of functioning as messengers from God. Genesis 1:14–15 appears to have comets chiefly in mind when it refers to “lights” that are “for signs”:

God said, “Let there be lights in the expanse of the heavens to separate the day from the night. And let them be for signs and for seasons, and for days and years, and let them be lights in the expanse of the heavens to give light upon the earth.” And it was so.