While there are skeptics and camera experts out there
Who claim ALL orbs are reflections off dust particles or mositure droplets, there appears to be a group including PhD physicist W. Tiller who think that something else is at work here.
In "The Orb Project," Ledwith and Heinemann present their fascinating discoveries, along with practical tips that amateur digital photographers can use to photograph orbs and properly distinguish them from "false" orbs that are really dust or water particles"....
This is not for everybody, nor am I ready to debate anyone on this, but here's a book on the subject with a foreward by <Tiller.>