To Don Willems (Member 64,767), these clouds looked like the head of a shark swimming through the night over Eidsvoll, Norway, with the full Moon as its eye.

The pale disc of light around the Moon with a bronze and orange outer fringe is the optical effect known as a corona. It can appear when the Moon is veiled by thin cloud, in this case the high, dappled layer of cloud known as Cirrocumulus. A corona is caused by the bending, or diffraction, of moonlight passing around tiny cloud droplets. Although coronas can also appear in the dazzling light close to the Sun, they are much easier (and safer) to observe like this around the Moon.

The bright bluish-white central area of a corona is called the aureole, which is often fringed with brownish hues. Depending on the position of the cloud and the varying sizes of its droplets, the shape is often uneven. It can, like Don’s, extend more one way than the other and even have a dark gap of clear sky – like a shark’s wide-open, but toothless, maw.