That image shows clearly what would be the best places to strike from outer space.
I've been thinking that all of those people that are worried about UFO's and aliens visiting Earth should get behind a movement to go underground, that way we don't announce our presence to any potentially hostile aliens.

Seriously, astronomers do worry about all this light going up into the atmosphere because it makes observation of starts difficult for observatories near cities. There's been some attempts to get city lights directed so that there's not much light leakage upwards, not that they've been succesful even if it would also be more energy efficient, less power to light the same area if you are not wasting energy to light up the sky.

I actually think that underground dwellings would be cool, more extensive patio, garden and parking space above too.