防紫外线的魔毯(双语音频)
Water Blankets Forming Planets
In 2008 astronomers discovered surprising amounts of water molecules where planets were forming near young stars. But how, they wondered, could those molecules survive? They should have been destroyed by ultraviolet radiation. In theory, planetary dust could block out UV rays, but the dust was bound up in the creation of those young planets. So what's protecting the water? Now researchers at the University of Michigan believe they have the answer, which they published in the December 18th edition of the journal Science.
2008年，天文学家在年轻恒星附近形成的行星上发现了数量惊人的水分子。可这些水分子怎么可能存活下来呢？他们本应被紫外线杀死的了啊。理论上行星星尘可以把紫外线挡在外面，可在这些年轻行星的形成过程中，星尘是挤成一团的。这么说来，到底是什么东西在保护水分子呢？现在密歇根大学的研究者们相信自己找到了答案，并将其研究成果刊登在12月18号的《科学》杂志上。
The regions where planets are being created are incredibly chemically productive, rapidly generating new compounds. According to the researchers, some water molecules surround the almost-planet dust and act as almost a sacrificial layer. The water molecules absorb the ultraviolet rays—and, though those molecules are destroyed, the embryonic planet is shielded. And the region is producing water faster than the protective layer is being destroyed.
行星正在形成的区域不断迅速产生着新的化合物，其化学活性高得令人难以置信。研究者表示，一部分水分子包裹着未来的行星星尘，充当牺牲者的角色——这些水分子吸收了紫外线，所以即使它们被杀死了，处于形成初期的行星还是受到了保护。更何况水分子生成的速度比被杀死的速度要快。
The scientists say this action is similar to our ozone layer, which blankets us with protective shielding from UV radiation. They tested this idea in computer models and found that the results mirrored the observations. Seems that having water when a planet’s finished requires sacrificing some in the process.
科学家们说水分子的这种行为与我们地球的臭氧层类似，都是保护我们不受紫外线侵害的“毯子”。 他们建立电脑模型对这一推测进行检验，发现结果正好印证了他们的观察。看来行星快完全成型的时候，是需要一些水分子做出牺牲的。
—Cynthia Graber
