经济学人下载:太阳物理和古生物学:"石"事求是(1)

Science and Technology: Solar physics and paleontology: Set in stone
科技：太阳物理和古生物学：“石”事求是

An ancient forest reveals the sun’s behaviour 290m years ago.
远古树木向人们揭示二亿九千万年前的太阳活动情况。

Every 11 years or so, a new sunspot cycle begins.
每隔11年左右，太阳黑子就会迎来一个新的活动周期。

Sunspots are apparent blemishes in the sun’s photosphere, the layer which emits its light.
太阳黑子是太阳光球层（即太阳向外发射能量的主要大气层）上的明显黑斑。

Though still hot (about 3,500°C) , they are cooler than their surroundings (about 5,500°C) and thus appear dark by contrast.
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。

A cycle starts with spots appearing at mid-latitudes in both northern and southern hemispheres.
在活动周期开始时，黑子出现在太阳南北半球的中纬度上。

Over time, the spot-generating areas migrate towards the equator.
随着时间推移，产生黑子的区域不断向赤道移动。

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,
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，

until the spots vanish and the cycle renews.
宣告一个完整的黑子活动周期结束。

On Earth, the increased illumination of solar maxima drives photosynthesis, and thus plant growth.
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。

That permits botaniststo use trees’ annual growth rings to work out what sunspot activity was like hundreds, and occasionally thousands, of years ago.
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。

Determining solar activity millions of years ago, though, has not been so easy.
但是想要推断几百万年前的黑子活动就不这么容易了。

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,
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，

and how they might have changed over the course of time.
以及其循环周期在漫长的岁月中是否发生了变化。

Now, Ludwig Luthardt and Ronny Rossler of the Natural History Museum of Chemnitz, in Germany, have cracked the problem.
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 Rossler已经解决了这个问题。