Why did I see two suns?

We put this to physicist Matt Middleton, from the University of Cambridge...

Matt - Aliens!

Kat - OK. Right, next question. moving on.

Matt - When's the next question on poo coming up. Right.

Sandy - you're not mad. The scientific name for what you say is parhelia; they're commonly referred to as sun dogs. The earliest reference I can find to this was from Aristotle who died in 322 BC, so these have been documented for a very long time. I don't know why nobody else saw it, perhaps they weren't looking at the right place in the sky.

The reason that you see these things is refraction of light. We're all familiar with refraction of light, we've all seen rainbows. We probably, as a child, had a prism or something like this or maybe cooler toys. Maybe my parents fobbed me off with something pretty weird...

Kat - Cooler kids have cooler toys than just prisms.

Matt - Essentially, it's refraction of light. So light bends as it enters a medium of a different density. What happens is if it's very, very cold you get crystals forming in the atmosphere and they act as prisms, so they bend the light rays as they pass them. So, as these crystals float downwards and the horizontal faces become more edge on, you see the light refract horizontally, so you see them to the left and the right of the sun. And those are sun dogs.

Eleanor.

Eleanor - How often does this happen - how have we been missing this?

Matt - Well, I don't think they've been missed, but you do have to have a certain combination of weather to actually get those. So again, it has to be quite cold so you will see them quite often in winter and it probably also helps that the Sun is quite low on the horizon as well. So you do see them but we just don't see them all that often.

The other thing to remember is that you're refracting light around so those two mini suns won't be as bright as the main boy so they are a little bit fainter.