Guess you just had to be there

I guess you could put this one in the "You had to be there to see it" file. Late last week there was a transient phenomenon in the evening sky, it is called a sun dog, or parhelion, which means along side the sun and it lasted only about 15 minutes.

A sun dog is a fleeting event which could last from 10 minutes to an hour. It is when a blotch of light appears in the sky near the sun looking like a rainbow only in a blob, not the usual arch that we are accustomed to seeing.

The event is related, however, to the same principle which causes the rainbow arch; light from the sun is refracted through water droplets into its red, green, and blue components.

Only in this case the light from the sun is refracted through ice crystals in the cirrus or cirrostratus clouds near the horizon and is most usually seen at sunrise or sunset.

These sun dogs, or false suns, appear about 22 degrees on either side of the sun, or in rare events above the sun. In the event where the sun dog is above the sun all three are sometimes connected by an arc of light.

I have seen one of those three sun events. It was about two years ago at about an hour and a half before sunset. I was traveling west on the interstate and the sun dogs on the left and right appeared first then the sun dog over the sun with the arches came a few minutes later. It was quite a sight to watch. I pulled the car over to take it all in and of all occasions to be without a camera.

These sun dogs can also be in the form of a bright spot without color. In that case the light if only reflected off the ice crystals and not refracted. It is the refraction that gives the colors.

While prediction of sun dogs is near to impossible a good way to guess at their pending appearance is to look for the cirrus or cirrostratus clouds, the thin, white, feathery kind of clouds, near the horizon at about sunrise or sunset. Look 22 degrees on either side of the sun for the rainbow or bright white spots and hope you have a camera.

SKY WATCH

All of the excitement about the conjunction of Saturn and Mars has passed. It is too bad that on the two most critical evenings for viewing it was cloudy with thunderstorms in this area. Both planets are still in the early evening sky but are rapidly moving into the bright glare of the setting sun and may not be visible much longer. However, bright Jupiter has joined the evening crew rising in the southeast at about 8 p.m. located in the eastern edge of Sagittarius. You will find Scorpius, the scorpion to its right with the distinctive shape of the three stars for the head and claws and the "J" hook shape of the body and tail with two stars for the stinger in the tail. Bright Antares marks the heart of the beast. If you look real hard in the west about 30 minutes after sunset you might be able to find bright Venus just above where the sun sat. You will probably need binoculars to pull our planetary twin out of the glare. Third quarter moon, July 25.

NEXT TIME:

More astronomical blathering.