The 16th-century Italian polymath Gerolamo Cardano is known today for his work on algebra and probability theory. But he also provided an account of a rare meteorological phenomenon in Milan, when there was a report of an angelic visitation.
Cardano ran to the spot where, along with 2,000 other people, he saw what appeared to be an angel hanging in the air. “The strangeness of the sight filled everyone with amazement,” Cardano records in his book On Medicine.
The only person present not amazed was a lawyer. He pointed out that the winged figure was in fact a projection, an image of the bronze angel on the top of the bell tower of San Gottardo reflected on to low cloud by the rays of the sun.
Such images tend to be blurred. Gotham’s Bat-Signal in the Batman movies may look simple, but it is hard to replicate in real life because clouds are uneven and make poor screens.
On 25 December 1930, the inventor Harry Grindell Matthews projected the image of an angel above Hampstead Heath in London with the message “Happy Christmas”, but like other plans for cloud-based advertising, it did not come to fruition because of the poor quality of the images.
Modern cloud projectors using lasers suffer the same problem. When the artist Dave Lynch projected a galloping horse above Nottingham in 2015, though recognisable it was indistinct due to the uneven cloud.
To so impress the crowd, Cardano’s angel must have been cast on to an unusually – if not miraculously – thick and even cloud.
