细谈光污染：一起守护夜的黑

灯火辉煌的城市，光影交错。在欣赏现代科技带来的炫目夜景时，我们是否意识到——用光线填满的黑夜，已遮蔽了深邃苍穹那点点繁星?

You may think that light pollution isn’t something extraordinarily important. You may believe that every other type of pollution has a larger impact on the environment than light pollution does. You may not even have heard of it before. It may not be polluting our lakes, our air or the Earth’s living creatures, but light pollution is serious, and it needs to be addressed by everyone.

Light pollution, or “sky glow”, is the glow you can see at night above cities and towns. Light pollution is a problem that has been accompanying man ever since he started his first fire some 15,000 years ago, and technology has only made it worse. Light pollution is the stray light that comes from streetlights, billboard signs, buildings, parking lots, sports arenas and any other source of illumination that is reflected or directed into the atmosphere. Light pollution is made worse with air pollution, as the small particles that float in the air serve to scatter and reflect the light,compounding the problem. The effect of light pollution is to reduce the contrast, and therefore the visibility of dimmer objects in the night sky, which affects professional, as well as amateur astronomers. Light pollution has obscured our view of constellations, meteor showers, and even the planets.

Light pollution exists on every continent except Antarctica. Urban light pollution means that one-fifth of the world’s population can no longer see the Milky Way with the naked eye. Many city kids, even if they did peer through the orange smog above their heads, would probably see only a handful of stars. We have lost our view of the stars, and we have mucked up our nighttime environment as well. Astronomers are calling for the dark places on Earth to be preserved as national parks, so that we do not lose completely ourwindow on the Universe.

Light pollution impacts astronomical research and can even affect human health. The excess illumination also affects wildlife in various ways from altering migration routes to eating habits and breeding behavior, to name a few.

Lots of people find the ever-brightening night annoying, and animals that areprogrammed to prefer the dark may avoid brightened habitat. Sea turtles can get lost searching for a beach to lay eggs, and their hatchlings may confuse over-lit beachfront resorts for the ocean horizon, wasting precious energy needed to find the sea and escape predators. Because their necks aren’t yet long enough to see things far away, baby turtles rely on the mirror image of the moon to guide them to the sea, to begin their new life. A car may even hit a particular turtle, which was thinking the light from a nearby city was moonlight reflecting off the ocean waves. Birds that live in and around cities can die because of sky glow, too. The abundance of bright lights can blind them, leading to countless collisions with buildings, billboards and other tall structures.

These are merely a few of the possible negative effects light pollution has on our world. A very serious issue in our modern-day society is that light pollution is a terrible waste of energy.

Reducing light pollution is not difficult. Light pollution is the easiest type of pollution to end. On an individual level, people can help reduce much sky glow by using lighting only when necessary and by choosing well shielded lighting fixtures. The stars above us are a priceless heritage—not only for astronomers but for all humans. More of our children should be able to look up at night and see that the Milky Way is not just acandy bar.

或许你觉得光污染不是什么了不得的大事。或许你认为其他任何一种污染对环境造成的影响都要比光污染严重。没准儿在此之前你连听都没听说过光污染。或许此刻它并没有污染湖泊、空气或者地球上的生物，但是光污染之严重，需要大家协力解决。

光污染，也称“人工白昼”，在夜晚的城镇上空均可见到这种发光现象。自大约1.5万年前人类生起第一堆火起，光污染问题就一直伴随着人类，科学技术只是令这一问题更加严重而已。光污染属杂散光，来源于街灯、广告牌、建筑物、停车场、露天体育场以及其他反射或直射入大气层中的照明光。而空气污染又使光污染问题愈发严重，因为漂浮在空气中的小颗粒通过散射和反射光线，加剧了这一问题。由于光污染导致明暗对比降低，夜空中较暗物体的能见度因此而下降，这给专业及业余天文学者都造成了影响。光污染使星座、流星雨甚至行星都变得模糊不清，遮蔽了我们的视线。

除南极洲外，各大洲均存在光污染。城市光污染意味着世界上五分之一的人都无法再用肉眼看见银河。而许多在城市的孩子，即便他们能透过头顶上方的橙色烟雾凝视夜空，瞥见的也很可能只有屈指可数的几颗星星。我们已经看不见星星，也破坏了夜晚的自然环境。天文学家们呼吁，将地球上无光源的地点保护为国家公园，这样才不至于彻底丧失我们了解宇宙的窗口。

光污染不仅影响天文学研究，甚至还会影响人类健康。过度照明也会对野生动物造成不同方面的影响，譬如，改变迁徙路线、摄食习惯和繁育行为等。

许多人都会觉得持续明亮的夜晚很烦人，而天性喜黑的动物或许也会避开明亮的栖息地。海龟会在寻找海滩产卵的途中迷路，新生的小龟则会把过于明亮的海滩度假胜地误认为是大海的水平线，从而浪费掉寻找大海、躲避天敌的宝贵精力。由于幼龟颈部不够长，视物不远，因此要依赖月亮的映像引导它们爬向大海，开始新的生活。一只这样的幼龟甚至可能会被汽车撞到，因为它误以为附近城市的灯光就是从海浪反射而来的月光。生活在城市及周边的鸟类也会死于人工白昼。大量的强光令它们无法视物，从而导致无数次撞上大楼、广告牌及其他高层建筑的事故发生。

这些仅仅是光污染可能给我们的世界所带来的几种负面影响。现代社会面临的一个非常严重的问题就是光污染是对能源的可怕浪费。

减少光污染并不难，它是最容易消灭的污染类型。就个人而言，仅在必要时使用照明，且选择遮光性能好的照明设备，就能有助于大幅减少人工白昼现象。我们头顶上方的点点繁星，不仅对天文学家而言是无价遗产，对全人类来说也是如此。我们应该有更多的孩子能够仰望夜空，眼中所看到的银河不应仅仅只是(模糊的)“一条糖块”而已。