Florence, Italy — 9 December 1731
Unexplained luminous “cloud”
“A luminous cloud was seen, driven with some violence from east to west, where it disappeared below the horizon.” A contemporary author named Bianchini speaks of several strange luminous spheres making a whirring sound.
Source: Robert Mallet, “Catalogue of recorded earthquakes from 1606 BC to AD 1850,” Annual Report of the British Association for the Advancement of Science (1852), and “Third Report on the facts of earthquake phenomena,” id., 1853 and 1854. Case: W280