【经济学人】“石”事求是丨2017.01.21丨总第789期

EVERY 11 years or so, a new sunspot cycle begins. Sunspots are apparent blemishes in the sun’s photosphere, the layer which emits its light. Though still hot (about 3,500°C), they are cooler than their surroundings (about 5,500°C) and thus appear dark by contrast. A cycle starts with spots appearing at mid-latitudes in both northern and southern hemispheres . Over time, the spot-generating areas migrate towards the equator. As they do so, the amount of light and other radiation the sun emits first increases to a maximum and then decreases to a minimum, until the spots vanish and the cycle renews.

每隔11年左右，太阳黑子就会迎来一个新的活动周期。太阳黑子是太阳光球层（译者注：即太阳向外发射能量的主要大气层）上的明显黑斑，虽然其温度很高，可达到3500°C左右，但与大约5500°C的周围环境相比温度要低得多，所以显得更暗。在活动周期开始时，黑子出现在太阳南北半球的中纬度上。随着时间推移，太阳发出的光能与其它辐射能逐渐达到峰值，随后不断减弱，直至黑子消失，宣告一个完整的黑子活动周期结束。

• Sunspot ['sʌnspɒt] ：n. 太阳黑子

• Blemish ['blemɪʃ] ：n. 瑕疵；污点

• Hemisphere ['hemɪsfɪə] ：n. 半球
  

On Earth, the increased illumination of solar maxima drives photosynthesis , and thus plant growth. That permits botanists to use trees’ annual growth rings to work out what sunspot activity was like hundreds, and occasionally thousands, of years ago. Determining solar activity millions of years ago, though, has not been so easy. But it is of interest to solar physicists, who wonder how far back into the past the oscillations of the sun’s magnetic field that drive the cycle go, and how they might have changed over the course of time.

在地球上，日光亮度的不断攀升在最大程度上促进了光合作用，从而加快植物生长。这一现象使得植物学家可以通过树木每年都会生长的年轮来判断数百甚至数千年前的太阳黑子活动情况，但是想要推断几百万年前的黑子活动就不这么容易了。既便如此，太阳物理学家依然对此兴趣盎然，他们想要知道这种由于太阳磁场振荡而导致的周期性现象到底始于何时，以及其循环周期在漫长的岁月中是否发生了变化。

• Photosynthesis [,fəʊtə(ʊ)'sɪnθɪsɪs] ：n. 光合作用

• Botanists ['bɒtənɪst] ：n. 植物学家

• Oscillation [,ɒsɪ'leɪʃn] ：n. 振荡；摆动
  

Now, Ludwig Luthardt and Ronny Rössler of the Natural History Museum of Chemnitz, in Germany, have cracked the problem. They have been able to apply the tree-ring method to petrified trunks from a nearby fossil forest. This forest (imagined in an artist’s impression above) was buried by a volcanic eruption 290m years ago, during the Permian period . And, as they report in Geology, Mr Luthardt and Dr Rössler have found that the sunspot cycle was little different then from what it is now.

目前，德国的开姆尼茨自然历史博物馆的两位研究人员，Ludwig Luthardt和Ronny Rössler已经解决了这个问题。他们能够将判断树年轮的方式应用在附近石化森林的一颗石化的树木上。这个森林（用一个艺术家的感觉脑补一下这个森林吧）在2亿9百万年前的二叠纪时，被火山喷发所淹没。Luthardt和Rössler博士在《地质》杂志中发表的报告里提出，他们发现2亿9百万年前的太阳黑子周期与现在差别不大。

• petrify ['petrɪfaɪ] ：vt.使……石化；使……惊呆

• fossil ['fɒs(ə)l] : n.化石

• permian ['pə:miən] : n.二叠纪
  

The Chemnitz fossil trees, mostly conifers and ferns, are particularly well preserved. Volcanic minerals seeped into them soon after the eruption and petrified them before bacteria and fungi could rot their tissues away. Mr Luthardt and Dr Rössler selected 43 of the largest specimens