I go with Salamander’s response.
http://ghoststudy.com/main/fakepageorbs.html
http://www.iprfinc.com/brian9.html
As a digital photo nut [even delving into IR and UV, for kicks] I’ve “photographed” more “orbs” than I can count.
99.9% of the time, it’s dust/moisture/pollen/bugs/whatever.
There’s one ‘friendly’ reddish-orange one that always shows up in the photos I take on “Suicide Ridge” right beside my house.
Have no clue “what” it is but the little bugger’s almost always showing itself somewhere in the area, no matter which camera I’m using.
The stuff that really intrigues me more are the ‘mists’ that pop up in night shoot cemetery photos when the atmospheric conditions simply do not exist for them to occur “naturally”.