That's fascinating! It's good that you had the 10-20 with you when this occurred, and that you knew what settings to use to capture it so nicely.
I just noticed that I had already commented on this. It's interesting that my reaction was the same as before.
That is amazing, what a brilliant shot! I didn't even know about solar haloes, but it does explain something I saw once - it would have been a tiny fragment of one.
Wow, I just stumbled onto this shot after seeing your "Busses" photo... but I just saw my first solar halo today, complete with rainbow spectrum... of course I didn't have my camera! Great shot and an amazing phenomenon.
This is just too cool. I have always wanted to see one of these. We get parts of them in this area, but I have never seen a full circle like this. You were fortunate to have the 10-20 mm with you so that you could get the whole scene the way you did.