【英语时差8，16】光污染

 To really behold¹ the stars these days, you have to travel far from cities and towns to escape urban glow.   The magnificent sight of the Milky² Way, for example, can now only be seen in rural areas. But why do we shine light up into the sky in the first place? We need light shining down on streets and walkways--not up into the sky!

Look around your neighborhood. Are there security or street lights shining directly into your windows, or up into the sky? Billboards³ lit from below, aiming light up, instead of down? Misdirected light is not only a concern to astronomers⁴ and stargazers who love the night sky--it's also a waste of energy. The International Dark Sky Association, a non-profit group that educates people on light pollution, estimates that unnecessary light wastes a billion dollars a year in the US.

So what can we do about light pollution? Use light fixtures⁵ that shield the bulb, directing light down where it's needed. This prevents light from shining up into the sky, and from shining sideways into our eyes, where it only blinds us by its glare. Motion sensors⁶ and timers limit unnecessary light, and energy efficient bulbs decrease energy use.

Astronomers particularly like low pressure sodium⁷ lamps because their light is mostly one color, so it's easy to filter out of a telescope's view. After changing their streetlights to downward-directed, low pressure sodium lamps, the city of San Diego saved millions of dollars in energy costs per year. And gained a better view of the stars, to boot!   

1 behold   

v.看，注视，看到

参考例句：

• The industry of these little ants is wonderful to behold.这些小蚂蚁辛勤劳动的样子看上去真令人惊叹。
• The sunrise at the seaside was quite a sight to behold.海滨日出真是个奇景。

2 milky   

adj.牛奶的，多奶的；乳白色的

参考例句：

• Alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
• I like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。

3 billboards   

n.广告牌( billboard的名词复数 )

参考例句：

• Large billboards have disfigured the scenery. 大型告示板已破坏了景色。 来自辞典例句
• Then, put the logo in magazines and on billboards without telling anyone what it means. 接着我们把这个商标刊在杂志和广告看板上，却不跟任何人透漏它的涵意。 来自常春藤生活英语杂志-2006年4月号

4 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

5 fixtures   

（房屋等的）固定装置( fixture的名词复数 )； 如（浴盆、抽水马桶）； 固定在某位置的人或物； （定期定点举行的）体育活动

参考例句：

• The insurance policy covers the building and any fixtures contained therein. 保险单为这座大楼及其中所有的设施保了险。
• The fixtures had already been sold and the sum divided. 固定设备已经卖了，钱也分了。 来自英汉文学 - 嘉莉妹妹

6 sensors   

n.传感器，灵敏元件( sensor的名词复数 )

参考例句：

• There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
• Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句

7 sodium   

n.（化）钠

参考例句：

• Out over the town the sodium lights were lit.在外面，全城的钠光灯都亮了。
• Common salt is a compound of sodium and chlorine.食盐是钠和氯的复合物。