Have you ever looked up at the clouds and seen what looked like a small part of a rainbow above you? A popular name for this optical effect is “sun dog,” and the scientific name is “parhelion”.

I recently received a question from a reader asking if all rainbows are actually round. I have to admit that my initial response was “no” because I’ve never heard of a completely circular rainbow. However, by definition, rainbows could potentially be round.