Sun Dogs, Moon Dogs, and Halos
I saw the coolest thing on April 1, and this is not a belated April Fool’s prank. The midday sun was encircled by an enormous bright & beautiful halo. It looked like a giant eye, with a very clear blue sky as background. The intensity and clarity of this halo was almost alarming, quite eldritch really. I had once before in my life seen a halo around the sun, also in South Florida. Somewhat ironically, given my sub-tropical location, these halos are caused by ice particles in the atmosphere. A strong light source interacts with the ice crystals, which can reflect and refract the light, sometimes breaking it up into its component colors, all depending on the shape of the crystals themselves.
Sun Halo, Islamorada, Florida Keys
I had believed this phenomenon to be called a “sun dog,” but have since learned that sun dogs are bright spots of light sometimes accompanying a sun halo such as this. Sometimes called a “second” or “mock” sun — more formally a parhelion — I couldn’t make out any sun dogs with this halo.
Both beautiful and uncanny, they’ve undoubtedly caused quite a panic throughout history. But we’re no longer such superstitious creatures, are we?
And not to be outdone, the moon can be graced with a halo also. This one was shot outside my house in Miami. The dots across the lower right are the blinking marker lights of a passing plane in this long-exposure image:
Moon Halo
Panic! It's a Sun Halo!
Kenneth Setzer 