A Collection of Ancient Reports of Strange Aerial Object, by a NASA's Richard Stothers (NASA Goddard Institute for Space Studies).

 The most liberal attitude would allow that, to an ancient obser- ver, many aerial phenomena were mysterious and hence to some extent unidentified, despite the observer’s ability to describe them in familiar subjective terms and despite ancient attempts at theorizing about their nature. Today we can filter out the most obvious cases of conventional phenomena, in spite of the archaic terminology used to describe them. The approach adopted here will be to search for aerial phenomena in the more reliable ancient reports that look like modern UFOs, but without ignoring other manifestations of “strangeness.” My working hypothesis will be that most such reports can be explained by conventional scientific ideas and that, among all the reports, only those that defy reasonable interpretation after full ana- lysis can be said to resemble the most puzzling reports made today.

• In 217 BC “at Arpi round shields (parmas) were seen in the sky” (Liv. 22.1.9; Orosius 4.15). A parma was a small round shield made partly or wholly of iron, bronze or another metal; we do not know whether the luster of these devices (and not just their shape) was intended to be an element of the description. Mock suns are an unlikely explanation, since in the Roman prodigy lists these were routinely described as “double suns” or “triple suns” (i.e. two mock suns on either side of the real one).

• In 212 BC “at Reate a huge stone (saxum) was seen flying about” (Liv. 25.7.8). The implication would seem to be that the object in question was a stony gray color; that it is said to have moved irregularly (volitare) leaves open the possibility that the object Livy describes was a bird or some kind of airborne debris.

Sporadic reports of similar objects continue to appear after this in the Roman prodigy lists. The immediate sources are again Livy and his extractors Pliny, Plutarch, Obsequens and Orosius.

• The same year, 91 BC, a much stranger object was noticed near Spoletium:

Furthermore, several Romans on a journey saw a gold colored ball roll down from the sky to the earth; after growing larger, it was seen to rise upward again from the earth toward the rising sun and to block the sun itself by its size.

Bicknell proposed that this was ball lightning. But outside of high altitude storm clouds, ball lightning averages only 23 cm. in diameter, and the description suggests something much larger than this. Although the reported vertical motion, drawn out duration and prevailing sunny weather are not unheard of in ball lightning observations, the combination of improbable characteristics makes this explanation unattractive. The object’s apparent trajectory appears more consistent with the approach, overhead passage and retreat of a bolide. On the other hand, an actual landing on or near the ground is strongly indicated.