Very rare “moon dog” seen in Fresno

I did a post on a pretty 22 degree halo in Fresno not too long ago. But, an even more elusive optical phenomenon decided to reveal itself: A moon dog. Just as the sun can have halos around it, so can the moon, and they’re both completely analogous. Moon dogs are rarer than sun dogs because the moon must be bright enough; in my case, it was a full moon.

In this photo, only one sun dog is truly visible (on the right), while part of a 22 degree halo can be seen on the left.

So, what are dogs anyway? Dogs are the the bright spots (or spot, as both aren’t always visible) flanking the moon/sun, often extending from a 22 degree halo (which may or may not be visible). Dogs are usually accompanied with other optical phenomenon; my photo reveals a very faint light pillar, the vertical light from the moon.

Rare Sun Halo seen in Fresno

Up in the sky, sometimes there are amazing things to look up at. If you looked up at the sky today, you likely saw a sun halo; a rainbow ring circling the sun. A sun halo is in the family 22 degree halos, which are formed by hexagonal ice crystals refracting light by 22 degrees. The halos can be caused by the moon as well, and can vary in appearance, such as the case with a Sun Dog, which is even rarer to spot in Fresno.

A closer view of the sun halo.
What a full blown sun dog looks like; last I saw one in Fresno it was much more faint. Image from Wikipedia.