Originally Posted by Clough
It could have been an orb. I can't discount them happening or not happening because I don't have enough evidence that would lead me to conclude that they exist or they don't. I have however, had enough experience with possible paranormal activity to which I have been witness, and that I lean toward being actual paranormal activity, that I could believe that they might exist. I have heard of them being visible to the naked eyes in such places as cemeteries. But, the first thing that I would do is to try and rule out any possible logical explanation for seeing one.
What was the weather like where you think you saw the orb? Hot, cold, summer, winter, foggy, etc.? Was this near a lot of trees? Why do you think that it might have been the spirit of your grandfather? Was it near a place where he might have been at some point in his life?