What happened
In Book II of his Natural History, written around AD 77, Pliny the Elder includes a short chapter on 'burning shields' (clipei ardentes) among the wonders of the sky. His single example is precise. In the year when Lucius Valerius and Gaius Marius were consuls, 100 BC, a burning shield darted across the sky at sunset from west to east, throwing out sparks. The same event appears independently in Julius Obsequens' Book of Prodigies, which drew on Livy. For the same year Obsequens records that around sunset an orb like a shield seemed to be carried across the sky from west to east, alongside a blazing torch seen far and wide at Tarquinii. The phrase clipeus ardens became a fixture of modern UFO literature, and 'clypeology' was even coined in Italy as a name for the study of such ancient sky 'shields'.
The original account
A burning shield darted across at sunset, from west to east, throwing out sparks, in the consulship of L. Valerius and C. Marius.
Pliny the Elder, Natural History 2.34, trans. John Bostock and H. T. Riley (1855, public domain)
The official explanation
Most historians and astronomers read the 'burning shield' as a bright fireball (bolide). A round glowing head, a trail of sparks and a steady west-to-east path across the sky are typical of a large meteor entering the atmosphere. Bostock and Riley's 1855 translation adds a note: 'Probably an aërolite.' The astronomer Richard Stothers, who studied Roman sky reports, interpreted Pliny's comparable account of a falling 'spark' as a bolide. Romans already used the word 'shield' as a label for round celestial lights.
The anomalous case
This is one of the better-documented ancient aerial reports because two separate Roman writers record it for the same year, with the same direction and the same time of day. Pliny gives the consular date, the sunset timing, the west-to-east track and the sparks. Obsequens, working from Livy, independently describes a shield-like orb borne across the sky at sunset in the same direction. Both writers use the specific image of a shield, a round, flat, rimmed object, rather than the 'torch' or 'beam' they use for meteors elsewhere in the same lists. Obsequens records a separate falling torch at Tarquinii that year, which suggests Roman record-keepers distinguished the two. Writers such as Harold T. Wilkins and later 'clypeologists' argued that a disc-shaped luminous object crossing the sky horizontally fits modern disc reports better than a falling meteor.
The strongest argument that this was something genuinely unknown or classified, with each claim attributed to the person who made it.
Documents
- Pliny, Natural History 2.34 (Bostock and Riley translation) report, perseus.tufts.edu
- Julius Obsequens, Book of Prodigies 45 (100 BC) report, attalus.org
Sources
- Pliny the Elder, The Natural History, Book II, chap. 34: Burning Shields (trans. Bostock & Riley) Perseus Digital Library, Tufts University
- Julius Obsequens: Book of Prodigies (trans. Alex Nice) attalus.org
- List of reported UFO sightings Wikipedia
- Final Report of the Scientific Study of UFOs, Sec. 5 Ch. 1: UFOs in History (Samuel Rosenberg) University of Colorado / NCAS
Witness reports elsewhere
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