Blue Flash of Setting Moon

From the photographer: “After the July full moon sunset shots over the Town of Ragusa (Sicily – Italy), analyzing the individual frames, I noticed that a ‘Blue Flash’ was captured in one of them.”

Technical details:
Canon EOS R5 Mirrorless Camera
Canon RF zoom 100-500 mm. lens @ 500 mm.
¼ sec. exposure @ ISO 2.000
Software: Photoshop
(No color processing was done; Cropped image)

Secondary Image:
Canon EOS 6D MarkII DSLR camera
Canon FD 300 mm. lens  @ f/6,3
Seven 0,3 sec. exposure @ ISO 3200
Software: LightRoom, Photoshop