This has been bugging me for a while, I'm not sure what I saw exactly. A few months ago there was some thin clouds blowing past the sun, obscuring it to the point you could easily look at the disk with the unaided eye. There was a dark spot, that looked like a sunspot as seen in filtered pictures of the sun. The clouds were blowing by fast and the spot didn't change position on the sun for 10-15 minutes I was watching it. Is a sunspot a rational explanation for it?