If it were Poisson's spot, it would have to be a scattered reflection of the spot. The spot is much dimmer than the light which surrounds the object that created it. Likewise, reflections from the ground would scatter it again. I'm having difficulty imagining that being visible amidst the daylight all around the plane.
I think it's a glory. It might come from haze near the ground. Or it could be a retrodirective reflection from the soil.
Paul
On Jan 14, 2013, at 6:06 PM, Aburr@aol.com wrote:
But could it possibly be a Poisson bright spot?
yes