Sky Glow and Light Trespass

At the very moment that humans discovered the scale of the universe and found that their most unconstrained fancies were in fact dwarfed by the true dimensions of even the Milky Way Galaxy, they took steps that ensured that their descendants would be unable to see the stars at all. For a million years humans had grown up with a personal daily knowledge of the vault of heaven. In the last few thousand years they began building and emigrating to the cities. In the last few decades, a major fraction of the human population had abandoned a rustic way of life. As technology developed and the cities were polluted, the nights became starless. New generations grew to maturity wholly ignorant of the sky that had transfixed their ancestors and had stimulated the modern age of science and technology. Without even noticing, just as astronomy entered a golden age most people cut themselves off from the sky, a cosmic isolationism that only ended with the dawn of space exploration.

An excerpt from Carl Sagan's Contact via Jason Kottke  who also links to The Dark Side in The New Yorker documenting the effects of light pollution.

Today, a person standing on the observation deck of the Empire State Building on a cloudless night would be unable to discern much more than the moon, the brighter planets, and a handful of very bright stars—less than one per cent of what Galileo would have been able to see without a telescope.

We are deprived of
a direct relationship with the nighttime sky, which throughout human history has been a powerful source of reflection, inspiration, discovery, and plain old jaw-dropping wonder. 
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Growing numbers of us pass most of our waking hours “in a box, looking at a box,” as Dave Crawford put it: we spend our days inside offices, looking at computer screens, and our evenings inside houses, looking at television screens.

What amazes us now in the night sky is what we humans have created.

We no longer look up to the heavens, we look down on ourselves.

Light pollution can be reduced with better design of outside lights that reduces sky glow and light trespass