Mike Polly, age 9, of Whiting, Iowa, for his question:

WHAT ARE SUNDOGS?

In astronomy halos are the large, luminous rings seen from time to time around the moon or the sun. These halos are probably formed by light rays which are refracted by particles of ice. This means that reflected light is bent together.

This type of halo is often red on the inside, then orange, yellow and white on the outside. They are often seen in the Arctic regions.

A cross is sometimes seen inside the circle, stretching outside the halo. Large spots of lights called parhelia also appear on the bands of the cross. These parhelia are sometimes called sundogs. Mock suns is another name for the perhelia.

Coronas are often called halos, but they have different causes.