April 19

You may have seen sun dogs if you looked in the sky on the morning of April 19, 2010. What is a sun dog? It is one several optical effects you can see near the sun. It is also called a parhelion.

If you look at the picture above, the spot of colored light on the right side of the sun is the sun dog. If you look closely at the picture below, you can see a sun dog on the left side of the sun as well.

A sun dog is formed when sunlight is refracted by ice crystals. Sunlight is bent by 22 degrees, which is similar to the formation of a halo (full ring around the sun.) Other than the look, the main difference between a halo and sun dog is the orientation of the ice crystals. Sun dogs are best seen when the sun is low.

April 20

There were no sun dogs in the sky on the morning of April 20, 2010, but the sunrise was still colorful.