Today, Google reminds its British users, is the 355th anniversary of Edmond Halley’s birth. (The attribution is questionable; the parish records for Haggerston in the year of Halley’s birth are not extant, and another possible date is the 29th of October. The ultimate source of Jean-Jaques d’Ortous de Mairan’s Eloge of Halley, the source of the November birthdate, is unknown. Although Halley’s most authoritative biographer, Alan Cook, plumps for October, the BBC, History Today, and Wikipedia all give November the 8th. Furthermore, until a sharp-eyed editor spotted it, Google was reporting the date as Halley’s 335th anniversary, not his 355th). Last Thursday, the 3rd of November, was the anniversary of the first appearance of a giant comet in the skies above Europe in 1679, which would remain visible for much of the next four months. This comet was part of a remarkable concentration of celestial activity in the late 17th century: comets also appeared in Europe in 1677, 1680-81, and 1682, the last being the comet that now bears Halley’s name.
By successfully extrapolating the periodicity of the comet of 1682 from previous sightings (in 1607 and 1531) Halley was able to predict the return of the comet in 1758. Its appearance, just about on cue, on Christmas Day of that year was hailed as a triumphant confirmation of Newtonian theories. Benjamin Martin, an indefatigable populariser of science in the eighteenth century and an enthusiastic advocate for Newtonian mechanics, confidently announced that it would “fill the minds of all astronomers with a ravishing satisfaction, as it has, by this return, confirmed Sir Isaac Newton’s rationale of the solar system, verified the cometarian theory of Dr Halley and is the first instance of astronomy brought to perfection.” It’s perhaps possible to detect a note of relief in Martin’s tone – he had, by publishing and lecturing widely on the comet’s imminent return throughout 1758, largely staked his reputation on Halley’s turning out to be right. The comet arrived just in time to vindicate Halley and Martin and to justify the interest and competing interpretations that had been lavished upon it.
Halley’s demonstration that comets might have their own orbital periods did not simply transform them from harbingers of catastrophe into stately processes in an ordered Newtonian universe. The act of prediction, predictably enough, turned the comet’s arrival into a news event of its own; the tension surrounding the verdict it was supposed to deliver on Newton’s cosmos was only heightened by its late arrival. (Simon Schaffer, C.B. Waff and Sara Schechner have all written illuminatingly on the ways in which their new-found status as (potentially) predictable phenomena did little to diminish the fury of interpretation surrounding comets.)
In the late 1670s and early 1680s, comets were concurrently the subjects of serious astronomical investigation, folkloric superstition, astrological prognostication, and polemical pamphlets. They were news events in themselves, generating trans-continental exchanges between natural philosophers who argued over their positions, trajectories, functions and identity; and they were simultaneously regarded as heralds and causes of political, religious or apocalyptic upheaval. The transformations in the state they were supposed to prefigure were of course unspecified, and so they were ready-made for partisan pamphleteers to appropriate as emblems of their adversaries’ evil. Ephemeral literature about them abounded. (One startling individual instance, cited by Schechner, is of a “blazing starre” striking dead a “deboysed Cavalier” in the act of raping a Roundhead girl in Totnes in 1642.)
Comets imaginatively fuse sublime remoteness with terrible agency – a conjunction that is apparently still potent. Schaffer’s argument, that the newfound predictability of comets didn’t make them safe, is nicely illustrated by returning to the question on which we came in, namely the reliability of some of the information thrown up by the world’s favourite search engine. Entering the title of Schaffer’s 1993 article, ‘Comets and the world’s end’, into Google yields an interesting top page of results: nothing for the article, four results predicting the world’s fiery annihilation-by-comet in the next few years, and six results debunking the other four…