Just as the sun is rising or setting on one of those hazy days of spring, you may get to see an unusual phenomenon. The sun will appear to have had pups: smaller reddish-orange spots that are nestled up close on either side. Called sundogs, these bright spots can’t show up on clear or cloud-covered days. They need just the right kind and amount of haze - which is why being able to see them is a fairly rare occurrence. Sundogs are just sunlight, reflected off ice crystals in the atmosphere. They’re not that different from a ring around the sun or moon. But if you’re lucky, you may get to see sundogs’ most unique forms - a pillar or even a cross. As you can imagine, early humans thought those forms looked a bit scary!
Mary Knapp, Weather Data Library