It had a cost, for in doing so we have intruded in the environment with such forcefulness it has suffered. So much so that we have now for a long time been growing concerns about our own capability to keep harvesting from once thought endless resources which are proving not to be.
Pollution is one of the aggressions we are inflicting in the environment, and the environment is also ... the night sky.
No doubt lighting is akin to comfort. We shudder at tales of just over 100 years back, where black streets, dim interiors were unavoidable consequences of sunset. To a good measure, civilization can be measured by illumination levels. Darkness suggests fear, insecurity, poverty. Shining streets suggest security, open spaces with no menaces lurking behind nonexistent shadows, welfare.
And this is true to a good measure, but as always, blind application of a recipe may be not only wasteful, it may be worst than useless.
What is light pollution?
The image at left is an answer for itself. All the photons which impinged on the satellite's camera made no good on Earth, and as you can see, they are a lot. They betray billions of dollars worth of electrical power sent skyward. Of course some spillover is to be expected, for when you illuminate a downtown crossing, light reflects from the streets, from buildings, and goes up. But a badly designed or badly maintained lighting fixture, sends light down where it should go, but also sideways, frequently glaring you out, and regularly upwards to be seen by survey satellites or perhaps some curious alien wondering which kind of mystery energy resources we have, that let us indulge in such exotic treats.
Or rooted habits which go unchallenged, like turning on your facade with brilliant floodlights to stand out in the neighborhood. Only of course that You are glared out, and the bad guys have a splendid stage to contemplate before committing to their wrongdoings.
The point is, wasted light costs money - lots of it - and does not go far as to provide security, in fact it may well be detrimental. And of course, our forbearers had a sky show we cannot even dream of today unless we pack and trek hundreds of kilometers to selected pristine backcountry where light pollution has not yet made a dent.
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