Nigel Calder’s latest successful foray into the exotic depths of space investigates one of the more psychologically compelling problems in astronomy – comets and their consequences. Comets have always fascinated us: it is the task of this book to document that fascination – it does not explain it. Calder’s previous spectaculars, such as Violent Universe or Einstein’s Universe, have tried bravely to give us an insight into those problems which astronomers now find exciting: black holes, quasars, pulsars, general relativity. The celestial world is a good resource for such works: we can rely on the amazement conjured into being by contemplation of the heavens. Comets, however, seem to raise a few problems. For modern astronomy, we are told, they are ‘trivial’. More illuminatingly, ‘most of the agencies that finance high astronomy would frown on the allocation of salaried astronomers and valuable telescope time to so frivolous a task.’
Comets are now ‘amateur’ objects, and they remain singularly attractive for the public even when they are ignored by, or at least are unimportant for, the professionals. Some of the motives involved in comet mania emerge here: the Japanese comet-watcher Kaoru Ikeya, for example, was the son of an alcoholic father and a mother who worked as a maid at a hotel: ‘He needed fame, but how could one so young achieve this? If he could attach his dishonoured name to a new comet, his glory and synonymously his family glory would be rung over all Japan.’ Evidently comets have to be seen as a resource for humans, a resource which can be used in lots of different ways, although comets themselves, as Calder takes some pains to emphasise, really are dull. Snowballs, fireballs or hailstorms, they orbit round the Sun just like planets but in erratic and lengthy orbits. This book is timed to preempt the flood of even more obviously exploitative works we can expect as the most famous of all comets approaches the Earth during the next six years. This comet, named after the late 17th-century astronomer Edmond Halley, takes about 76 years to make its way round its orbit. On 9 February 1986 it will reach its nearest point to the Sun. During the next few years it will be at its most visible from the Earth. Such events have always excited public admiration, interest and, occasionally, terror. Halley’s comet appears on the Bayeux Tapestry as a harbinger of King Harold’s doom. It was probably first spotted by the ever-watchful Chinese. In 840 AD an imperial edict in China forbade astronomers to mix ‘with civil servants and common people in general’ lest their knowledge of these terrible objects incite popular fear and unrest.
Calder suffers from no such constraints. He cheerfully documents, in some detail and with full colour illustration, both the development of our understanding of the nature of comets, and the kinds of popular response they have attracted. He also discusses two of the more interesting current uses of comets in scientific theory-making: the claim by the cosmologists Fred Hoyle and Chandra Wickramasinghe that life on Earth comes from the residue of a comet and that epidemics of influenza still come from comets; and the idea of some scientists at Berkeley that the dinosaurs were wiped out by a cloud of iridium left in the Earth’s atmosphere after the impact of a comet. Neither of these ideas is particularly new: Francis Crick, co-discoverer of the structure of DNA, appealed to comets as the origin of life on Earth in his theory of ‘directed panspermia’; in 1684 the anonymous author of a book called Cometomantia explained that ‘we must expect sickness, diseases, mortality, and more especially the sudden death of Great Ones’, after the passage of a comet; some explained the Great Plague of 1665 by appealing to comets; and in 1750 the French astronomer Pierre Maupertuis said that whole species must have perished in the past history of the Earth when comets came near. Evidently comets are uncomfortable neighbours for the planets in our Solar System: for several centuries they have been uncomfortable objects for astronomers to live with too.
For the plain fact is that astronomers are more interesting objects than comets. Judging from books like this, astronomers’ behaviour has been as bizarre as that of the most erratic body in the heavens. There is much more to the story of comets than the mere fascination of the public and the developing understanding of them on the part of the experts. They are a very useful hook on which to hang some widely-canvassed theories of the place of the scientist in our society. In statements like that of Hoyle, or in books like this one of Calder’s, we can detect something of the tension inherent in the privileged place of the expert in the modern world. On the one hand, modern ‘big’ science, of which astronomy is a very good example, justifies itself to its paymasters in essentially self-imposed terms. Technical spin-offs are mentioned, but the pursuit of pure knowledge is obviously an activity worth supporting, and comets certainly do not figure large on a map increasingly dominated by the visually unexciting but theoretically compelling objects of the new astrophysics. On the other hand, comets retain their place in popular cosmology. They might crash into the Earth, as something big certainly did in Siberia in 1908. They might spread disease, or move the Earth from its orbit, or foretell some human disaster or success. So they still exist as a resource which can be used by professional astronomers. The motives here are perfectly clear. Sciences such as astronomy are now distant from popular comprehension: the social relations of their production separate astronomers from an audience just as surely as they were separated by Chinese imperial edict. Science as a whole preserves its purity, and hence its licence to produce the truth, by exactly such a separation. The objectivity of scientific knowledge is closely connected to the taboo placed around its producers. The screams of rage emanating from a medical profession recently assailed by Ian Kennedy in the Reith Lectures bear eloquent testimony to this. Similarly, an obvious user of comets like Immanuel Velikovsky came under fire precisely because of his appeal to the wrong – that is, the popular – audience.
We can now see where comets fit in. Until the end of the 16th century comets were spoken of by two distinct kinds of commentator: they were the objects of astrology, foretelling disaster for the great and change for the many, while medieval philosophers knew from Aristotle that they were exhalations expelled from the Earth like mists and fogs. Two kinds of books were written on the subject: titles like Cometomantia dealing with judicial astrology; titles like Meteorologia dealing with scholastic philosophy. At the Renaissance new kinds of job and new kinds of book appeared. In the Baltic a Danish astronomer, without the aid of telescopes but with the encumbrance of an artificial nose gained after a wound in a duel, asserted that comets were not fiery exhalations from Earth, nearby in our atmosphere, but were further away than the planets. Their free and erratic paths, it was said, proved that the stately crystal spheres of medieval astronomy were imaginary. The period between 1600 and 1800 was the Age of Comets with a vengeance: their problematic nature dominated astronomy. Newton and his collaborator Edmond Halley established the basis of a mathematical theory of comets in the late 17th century. They were, however, just as concerned with what comets might do as where they might travel. They did show that comets move in regular orbits round our Sun, and Halley even predicted that some comets would return at mathematically calculable moments in the future. Of his predictions, only one was even vaguely correct. The comet of 1682 did return roughly 76 years later, as he had sketchily suggested. Calder blames Halley for reactivating comet mania by making such a prediction. However, astronomers saw comets as the carriers of divine activity round the universe, fulfilling the purposes of God for good or ill; and in that sense comet mania was precisely the goal of astronomy at this period. Halley and William Whiston, his contemporary, both said that Noah’s Flood had been caused by a comet. Newton said that comets revitalised the Earth with an active spirit carried along in their tails. Other writers suggested that comets might be the cause of the final conflagration; that they might represent the site of Hell itself; some even claimed that comets were inhabited, and that their inhabitants must be very good astronomers because of their excellent vantagepoint for viewing the Sun, planets and stars. The purpose of such suggestions, indeed the purpose of natural knowledge, was to create a sense of wonder in the audience, so that they would behave with the proper deference towards God’s own ministers here on Earth. One of Newton’s closest followers made a close connection between comets and kings:
Comets from far, now gladly would return,
And, pardon’d with more ardour burn.
Attraction now in all the Realm is seen
To bless the reign of George and Caroline.
The coronation of George II, the poet felt, needed support from heaven. Natural philosophers performed bizarre experiments in coffee houses and theatres to impress their paying audiences; the Christmas Lectures at the Royal Institution are a linear descendant of these events. Astronomers could offer their public scale-models of the heavens with electrical machines to help them demonstrate the magnificence of comets. No polite gentleman could be without his telescope and orrery. A leading French philosopher wrote in 1742 that ‘the greatest astronomers of the century have spoken of comets in a fashion designed to re-establish them in all of that terrifying reputation they once possessed,’ while one of his colleagues described such astronomers as ‘authorised prophets’. These prophets knew their job. It was a new one: that of licensed experts who could use the wonders of nature to impress their audience, and introduce them to the theatre of truth. Comets could act professionally on such a stage.
It is therefore misleading to picture the history of comets as a steady move away from wonder towards truth. We can trace a move from amateur wonder to professional wonder and on, after 1800 and right up to the present, to the contrast between professional boredom and professionally-produced wonder. For after 1800 the place of comets changed again. It changed because society changed, and so the job of the astronomer changed. Astronomers were more and more professionally organised, and more and more separate from their public. Robert Peel complained in the 1840s about the difficulty of justifying government support for astronomy to a Parliament of country gentlemen. Science was specialised, divided, demarcated. At the same time Peel’s problems could have been solved by keeping the public aware of the triumphs and grandeurs of the understanding of the heavens. From this moment the astronomer faces his public with two kinds of resource. On the one hand, his command of the system of the universe, his immense theoretical grasp of its complexities. On the other hand, the basic spectacle of the heavens themselves. Comets have kept their place because they are still spectacular, and we need to be reminded that science really is (literally) wonderful.
Where have we come since the wonder of the 18th century? In 1773 the whole of Paris was terrified to learn that a leading astronomer of the Royal Academy of Sciences was seriously discussing whether a comet might crash into the Earth. In Normandy pregnant women suffered still-births; Voltaire wrote a satirical poem mocking those citizens who had fled the city in terror. This comet scare recurred 18 years later, during the middle of a more obviously terrifying revolution in France. We might recall the effect of Orson Welles’s broadcast of War of the Worlds in the 1930s, which brought New Yorkers out of their homes and scurrying across the Hudson into New Jersey. We can also recall the recurrent ‘crazes’ of popular science which this book of Calder’s describes. We can remember Velikovsky, Von Däniken, the debate on UFOs in the House of Lords. Have we ‘grown up’ since the 18th century? Evidently not. The social structure of these events has, however, changed. In the early 19th century the figure of the professional scientist emerged, and he now pays a high price if he gets involved with the disreputable face of science. Magnus Pyke and Patrick Moore stay very close to the professional end of this division; Desmond Morris seems to be crossing over; and from Nigel Calder’s evidence the most recent effort by Fred Hoyle seems destined to be seen in the same way. Why? After all, as Calder explains, the work of Hoyle and Wickramasinghe is perfectly documented, with the formal appearance of accumulated statistics, detailed theory and considerable positive evidence. Furthermore, it is certainly not the prerogative of such glamorous scientists and glamorous theories to be notably fallacious. One contemporary astronomer, attacking a respectable theory of cometary origins, wrote in 1976 that ‘if the claims of science and reason are waived, there could be said to be something heroic about the way in which for a quarter of a century the numerous icy-nucleus proponents have stuck to their guns with not a shred of acceptable scientific evidence to support the theory.’ Surely the point is that Hoyle is discussed in books like this one and therefore is to be treated with mistrust by his colleagues. ‘Popularity’ is closely related to unsound science, precisely because ‘popularity’ and ‘purity’ seem to be mutually exclusive, and because purity is the precondition for the claims science makes to its high status. Wittingly or unwittingly, Calder may have done his best to destroy the slim chance Hoyle and his collaborators have of being treated seriously by even mentioning him. Calder himself reports the ‘heavy-handed scorn and vilification’ with which his own (correct) suggestion about the incidence of past Ice Ages was greeted by the professionals: this is symptomatic of the divide which separates science in our society from that society itself.
Comets symbolise most of these points: they are terrifying and so useful, and they are popular and so relatively taboo. There will always be sceptics, of course; and scepticism about the power of science, as a mid-18th-century English journalist explained, is both reasonable and necessary: ‘We all very well know of what ill consequence the common stories of ugly bugbears and hobgoblins are to children in general: scarce one pretty master or miss in a hundred that dares put a foot into the dark for fear of them and yet ridiculous as their fears are, I cannot think the gloomy imaginations of astronomers relating to comets are better grounded.’