The Cosmic Tusk

William P. Napier

Comets are jokers in the celestial pack. They irrupt, usually without forewarning, into the orderly progression of the sky. They cross the celestial sphere in weeks or months, growing one or more tails, before fading and disappearing from sight. On rare occasions a comet may be an awesome sight, and the historical literature of the past two thousand years is sprinkled with accounts of the fear induced when a great comet, its smoky red tail bisecting the heavens, appears in the night sky. In the remote past, tales of such apparitions were often conflated with stories of disaster on Earth. A comet called Typhon in Greek mythology was connected with a mythological flood, and the legend of Phaethon, in which the sun’s chariot went off course and the Earth was first burned up and then flooded, may describe an exceptional meteorite impact. There is good evidence that the sky in Neolithic times was dominated by a recurrent, giant comet, and that the Earth annually ran through an associated meteor storm of huge intensity. The origin of religion dates to these times and may be tied up with this spectacular night sky. The prospect that cosmic myths, megaliths and art dating from this time may have been responses on the ground to threats in the sky has in recent years moved from Velikovskian fancy to a subject for serious scholarly discussion. In more scientific times, too, it was often suggested that a comet striking the Earth might create create worldwide havoc. For example past encounters of Halley’s comet were supposed to have coincided with Noah’s flood in 2342 BC. This catastrophist view of Earth history was widely held until late 1830s. From about the middle of the 19th century, however, it was supplanted by a uniformitarian one, at least in the English-speaking world. Partly this came about because geologists came to recognise that the terrestrial landscape had been formed over aeons by gradual forces, by erosion and slow mountain building. The astronomers too played their part in this changing perception. Several periodically returning comets were found to be associated with annual meteor streams. It seemed that the end state of comets was nothing more exciting than a swarm of dust. By the time of the Victorians, the universe was seen as a more or less irrelevant backdrop to the affairs of Earth. Scientists were free to explain evolution unhindered by any thoughts of celestial disturbance. The occasional revivals of the catastrophist worldview became the domain of cranks. This long slumber lasted until the late 1970s.

Continue reading Rare Bill Napier Essay: Giant Comets — Messengers of Life and Death