In antiquity, comets came to have a reputation for being omens of disaster, portending the death of rulers, the outbreak of war, or the onset of plague, drought, or earthquakes. The intriguing question is: When and how did this notion become established in classical Greek and Roman culture? Surprisingly, the belief that comets are baleful signs cannot be documented until comparatively late.

An examination of textual and material evidence from antiquity, including an array of coins and artwork, demonstrates that in the Bronze Age and in the 5th and 4th centuries BC, comets were by no means always regarded as bad omens. On the contrary, some of this evidence indicates that even as late as the early decades of the first century BC, comets were occasionally treated as auspicious objects. The earliest attested expression of what was to become the stock view of comets as omens of calamity is linked to the return of Comet Halley in 87 BC. It is quite easy to understand how that comet in particular might have helped give rise to the belief that comets portended war and death because the comet of 87 was accompanied by both a devastating plague and the Marian Civil War at Rome. Two later comets that were observed in the same generation doubtless reinforced the notion that comets were messengers of doom: a comet in 49 BC that coincided with the outbreak of the civil war between Pompey and Caesar, and the famous daylight-visible comet of 44 BC that appeared four months after the assassination of Caesar. The weight of the evidence points to the conclusion that in the Ciceronian Age, there was a notable shift in the way the meaning of comets was interpreted. These celestial objects, which had always inspired wonder and awe, were henceforth chiefly regarded as messengers of doom and disaster.

Admission is free and open to the public. A reception will follow the lecture. Sponsored by the Adler Planetarium and the Archaeological Institute of America: The Chicago Society