"Paul Schlyter" wrote in message
...

The Black Drop is an effect of how our eyes perceive when two unsharp
edges between bright and dark approach one another. It can be readily
simulated by keeping two of your fingers as close to your eye as you can
and then let the fingers approach one another: they seem to touch before
they actually touch.

is that the same thing as seeing the drop effect in front of the sun?
somebody else explained on here, i think it was at metaresearch.org
or something, that it is due to moving cells of air in the atmosphere.

rj