While walking her dog along Craigville Beach in Barnstable, Massachusetts, US, Veronica Cote (Member 20,593) saw a different kind of dog in the sky. The bright patches flanking the Sun on the right and the left are parhelia, also known as sun dogs.

Sun dogs are examples of halo phenomena, many others of which you can see in this same sky. These include the big circle around the Sun that is known as a 22-degree halo and the bright patch on this circle directly above the Sun where an upper tangent arc touches the 22-degree halo. Just visible immediately above that, and curving downwards, is a rare one: the suncave Parry arc. And far above them all, looking like an inverted rainbow near the top the image, is a circumzenithal arc.

All of these halos are formed by the refraction of sunlight through the ice crystals in the thin layer of Cirrostratus clouds that Veronica spotted. The rare suncave Parry arc suggests that some of these ice crystals were in the shape of hexagonal columns that were oriented with one of their sides completely horizontal – like tiny, unsharpened pencils of ice resting on a table. None of this was of interest to Veronica’s dog, who was focussed on chasing the fiddler crabs.