Sun Dogs: The Two False Suns That Flank the Real One

On a cold, bright day you glance toward the sun, low over the horizon, and something is wrong with the sky. Flanking the sun, at the same height, hang two more bright spots, glowing and faintly rainbow-edged, like the sun has grown escorts. For most of history, people who saw three suns in the sky were certain it meant something, and armies and kings sometimes acted on it. What they were actually seeing was ice, doing geometry.

Sun dogs are one of the most striking and misread sights in the sky, and the explanation is as elegant as the omen was dreadful.

What you are actually seeing

A sun dog, more formally a parhelion, is an atmospheric optical effect caused by sunlight passing through ice crystals high in the atmosphere. When thin, cold cirrus clouds are full of tiny, flat, hexagonal ice crystals, and those crystals drift with their flat faces roughly horizontal, they bend sunlight by a fixed angle, about 22 degrees, and concentrate it into bright spots on either side of the sun. The bending also splits the light slightly by color, which is why a good sun dog shows a reddish inner edge fading to blue outward.

They appear at the same altitude as the sun, one on each side, and are most vivid when the sun is low. In very cold conditions, near the poles or in a hard winter, the display can be spectacular, sometimes accompanied by a full halo ring and pillars of light, so that the sun seems genuinely multiplied. The two flanking "dogs" that follow the sun across the sky are what gave the phenomenon its homely name.

The omens people read

Three suns in the sky was, understandably, taken as a portent. Ancient and medieval observers recorded parhelia as signs from the heavens, often of upheaval, division or the death and rise of rulers. One famous instance was interpreted before a medieval battle as an omen of victory, three suns read as a heavenly endorsement. Because the effect is dramatic, unusual and appears without warning, it slotted neatly into the human habit of reading the sky for messages.

It is worth being plain that a sun dog foretells nothing. It is weather, a specific arrangement of ice crystals, and its main practical meaning is meteorological: the high cirrus that produces it can signal an approaching change in the weather, which is a genuine and useful bit of folk forecasting, not a supernatural warning.

The residue in the cold sky

The optics are complete, ice crystals, a 22-degree bend, split light. What survives the explanation is the sheer strangeness of the sight. Knowing why there are three suns does not fully cancel the jolt of looking up and seeing them, and people still photograph a good display with a kind of unease, half certain it must mean something. Understanding covers the phenomenon. A thin residue, the ancestral pull to read a tripled sun as a sign, does not tidy away, and that is what our readers argue over.

Below, readers have filed their own sightings of false suns, halos and skies that seemed to signal something, each voted True, Fake or Not sure by the jury. Read them and cast your verdict.