In article ,
randyj wrote:
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.

I'm not sure what it says at metaresearch.org, but since the black
drop effect was seen when Mercury transited the sun as observed by a
spacecraft, the black drop effect cannot be due to either the earths
atmosphere or the atmosphere of the planet in transit.