Our Vanishing Nights
If humans were truly at home under the light of the moon and stars, we would go in darkness happily, the midnight world as visible to us as it is to the vast number of nocturnal (夜间活动的) species on this planet. Instead, we are diurnal creatures, with eyes adapted to living in the sun's light. This is a basic evolutionary fact, most of us don't think of ourselves as diurnal beings. Yet it's the only way to explain we've done to the night: We've engineered it to receive us by filling it with light.
The benefits of this kind of engineering come with consequences – called light pollution – whose effects scientists are only now beginning to study. Light pollution is largely the result of bad lighting design, which allows artificial light to shine outward and upward into the sky, it's not wanted, instead of focusing it downward. III-designed lighting washes out the darkness of night and radically alters the light levels – and light rhythms – many forms of life, including ourselves, have adapted. Wherever human light spills into the natural world, some aspect of life is affected.
Among mammals alone, the number of nocturnal species (be) astonishing. Light is a powerful biological force, and many species it acts as a magnet. The effect is so powerful that scientists speak of songbirds and seabirds being "captured" by searchlights on land or by the light from gas flares on marine oil platforms. Migrating at night, birds tend to collide with brightly lit tall buildings. Frogs living near brightly lit highways suffer nocturnal light levels that are as much as a million times brighter than normal, (throw) nearly every aspect of their behavior out of joint, including most other creatures. We do need darkness. Darkness is as essential to our biological welfare, to our internal clockwork, light itself.
Living in a glare of our own making, we have cut off from our evolutionary and cultural patrimony (遗产) — the light of the stars and the rhythms of day and night. In a very real sense, light pollution causes us (forget) the scale of our being, which is best measured against the dimensions of a deep night with the Milky Way — the edge of our galaxy — arching overhead.
