My pleasure, Michiel! I'm sure you can teach me some English too... [img]/phpBB/images/smiles/icon_biggrin.gif[/img]

But back to the OP...

There are plenty of signs of mankind on the night side of Earth. Lots and lots of artificial light sources.

And the smoke from the WTC was photographed from space, though I don't know if it was naked-eye visible.