Oh Yeah! They Know We're Here
If there is intelligent life out there zooming around in their interstellar craft then without doubt, should they happen upon us at night there would be little doubt that there is at least semi-intelligent life on this planet.
Here is what an alien would see if they passed close to Earth oribit over the North American Continent at night.
[View of parts of Canada, the USA, Mexico, Central America & Caribbean at night taken from the orbiting International Space Station]
Awesome pic but no way that was taken FROM the ISS, it's only 150 miles or so up. This pic was taken from waaay out there.
Cool picture. I couldn't help but notice how sparsely populated the western half of the US is (compared to the everything east of Texas). Must be all that desert.
Oh, I could tell you all about the wonderful emptiness of the Southwest! I't amazing to be able to go places and know there isn't another human being for miles. Very liberating. :)