The experience that I am about to share with you has happened on more than one occasion. I first noticed it when I was out fishing in the Rockies with some close friends of mine. I looked up to soak up the beautiful sky and noticed I saw what looked like to be a lot of bugs. I grabbed for gnats and nothing. I looked longer and they seemed far away but there were thousands of half circles outlined moving freely about the sky. They were translucent. The best way to describe them are eye floaties, though I can assure you this is not actually in my eye. These move a lot faster and seem to be miles and miles away. When I see this I get overwhelmed with happiness and calmness sensations. Anytime I have experience this I have asked people around me if they see anything strange. No one has ever seen it.
I can only see these when it is a clear sky and bright. I haven't tried on cloudy days too much as Colorado doesn't have many overcast days unless its snowing like crazy. I thought maybe it had something to do with me living in Colorado with the altitude but I recently visited IL and I could see them there as well. I just couldn't see as many.
I'm not 100% sure what this is, but I would like to hear what others think. I consider myself spiritual and get a lot of gut feelings that turn out to be true.