If falling stars are considered to be lucky, the opposite must be said of those vagabonds of the solar system that occasionally blaze a spectacular trail across our night-time skies. From time immemorial, comets have been regarded as portents of natural disaster or great civil disturbance in the realm. Pliny the Elder, for example, summed it up for his generation back in Roman times: "A fearful star is the comet, and not easily appeased, as was apparent in the late civil troubles when Octavius was Consul; a second time by the war of Pompey and Caesar; and in our own time when, Claudius Caesar having been poisoned, the Empire was left to Domitian, in whose reign there also appeared a blazing comet."
In 1066 the Saxons blamed Halley's Comet for the defeat of Harold by the Normans at the Battle of Hastings. Its presence over the battle-field on that occasion is commemorated in the Bayeux Tapestry, where it is shown as a prominent star with sweeping tail, being pointed at by the people on the ground.
Andreas Celichius, the influential 16th century Bishop of Altmark, came to a rather different conclusion about the origins and meaning of these mysterious cosmic apparitions. In 1578 he wrote that "the thick smoke of human sins rising every day, every hour, full of stench and horror before the face of God, becomes gradually so thick as to form what we call a comet, with curled and plaited tresses which at last are kindled by the hot and fiery anger of the Supreme Heavenly Judge." The good bishop's theory was somewhat discredited, however, by the wise remark of a contemporary sceptic: "If comets be caused by the sins of mortals, they would never be absent from the sky."
Here in Ireland, the 17th century Bishop of Kilmore and Ardagh, Dr Edward Wettenhall, was our expert on the subject. In 1682 he wrote a lengthy pamphlet called A Judgement of the Comet which became First Generally Visible to us in Dublin December XIII, about 15 Minutes before 5 in the Evening, Anno Domine 1680
His Lordship thought such superstitious notions rubbish. "The strange events pretended to be the effects of comets," he says, "have no more connection with them than that of Accidental Synchronism - and sometimes not that neither." But if some believe such things, it may well be no bad thing, says Dr Wettenhall: "They may conduce to stop the mouths of some of the grosser sort of Atheists, or make vain and inconsiderate people capable of serious thought, which thought pursued may well be happy to them in the end."