Their warnings point to the problem as well as revealing a missed opportunity. We have only been pitching our tents for a little while in the land of power stations and industry, so it is no surprise that we are sometimes blinded by its promise. Part of the advance of our technological society has been a steady if sometimes intermittent advance in the efficient uses of energy. However, when energy appears cheap, we tend to waste energy rather than use less of it. Light pollution represents a waste of a magnitude that almost no homeowner would allow inside their homes.
Interior lights bounce off of all the room's surfaces, providing for good general illumination.
Only small amounts of light will escape out of the windows. How strange it is, then, that when we attempt to light the outdoors, we often carelessly allow a large percentage of light to escape unused. Like a driver driving toward the light of the setting sun, such unshielded lighting creates glare and diminishes visibility. Our tolerance of wasted light means most lighting fixtures are oversized by at least a third in wattage. Many light sources are of an older, less efficient type, which means that opportunities often exist to significantly reduce energy consumption by switching to a newer, more efficient type of light source in a fixture with good control of the light output and proper shielding.