‘The moon quivered like a snake’: A medieval chronicler, lunar explosions, and a puzzle for modern interpretation

A marvellous sign and a fiery globe: a medieval English report of ball lightning

“…These are all the more impressive when considering that observation of partial eclipses was visually challenging in medieval times. In a detailed account of the partial eclipse of 13 September 1178, Gervase accurately describes the turning of the horns of the partly obscured solar disc to point downwards, as well as the changing colours close to maximum eclipse (Gasper and Tanner, 2020). The dates and times of lunar eclipses are accurately noted, though more succinctly.…”

“…His description of the splitting of the image of the moon on 18 June 1178 has received recent attention since Hartung (1976) suggested that the effect was associated with the formation of the far‐side lunar crater Giordano Bruno. We have subsequently shown that the carefully recorded details in the report can be explained in terms of atmospheric refraction and total external reflection from a hot column of air above a fire such as used for metal working or bell‐casting (Gasper and Tanner, 2020). This, together with the recent identification of other similar reports in other chronicles, effectively refutes any link to lunar meteorites.…”

A cooking pot lit by fire

“…He described unusual phenomena as the natural marvels that they were, rather than being associated with specific human events. In some cases, he appears to have been an eyewitness (Gasper and Tanner, 2020) but here he most certainly was taking information from a third party. Whatever his source concerning the appearance of the eclipse in England, he correctly recorded its date and time.…”