Hi,

Almost every orbs in digitals pictures are light relfection on dust pieces when they are close of the lens (i.e. out of focus).

It's easy to reproduce.  Try it yourself, it's fun!

When I worked as a school crossing guard.I saw what I thought was a soap bubble coming down the road.it came near the curb and moved close to me.I could not see through it.I kept saying to myself,what is it?I could reach out and touch it,but I did not.it was as big as a basket ball.it moved down and across the street to the orther side.than went strait up and I lost it in the fog.now this could have been an orb,but at the time i never knew what an orb was.George