There are other forces at work in the sun.  其内部还有其他的力量正在运作

Forces that change over minutes and over years.  这些力量可能在数分钟或数年内改变

Forces that tear the surface apart.  撕裂太阳表面

We are only now beginning to understand these forces  我们现在才开始了解这些力量

and the effects they have on the Earth.  及它们对地球的影响

But we have known about them for hundreds of years.  但我们早在几百年前，就知道它们的存在

Because the sun gets spots.  因为太阳上会出现黑点

Sun spots are dark regions on the surface of the Sun,  太阳黑子是出现在太阳表面的黑色区域

typically about the size of the Earth in terms of area.  一般来说，大小和地球差不多

Here's a live shot of one today.  这是今天拍到的即时影像

Unfortunately we've got a very windy day with high thin clouds,  可惜今天风很大，而且高空有稀薄的云层

so the picture's bouncing around and not very sharp,  所以画面晃得很厉害，画质也不清晰

but with very high resolution images we can see  但以高解析度来看，就能看到

detailed structure in the sun spot.  太阳黑子的仔细构造

The inner part of the sun spot,  太阳黑子的内部…

the dark umbra as we call it is dark  即所谓的暗影

only in comparison to the rest of the sun.  只是与太阳其他地方对比下，才显得黑暗

It's actually bright enough that it would blind you  其实暗影很亮，单独直视它的话

if you looked at it alone.  会瞎掉

The spots are not static.  太阳黑子并非静止不动

These video images show the edges of the spot crawling,  我们拍到的画面显示，黑子的边缘

almost as if it was alive.  正在鲜活蠕动

The movements of sunspots have been studied  自从伽利略用望远镜观察太阳

for four hundred years.  对其行为有重大发现后

Ever since Galileo trained his telescope on the sun  人类就开始研究太阳黑子的活动

and made the first crucial discovery about its behaviour.  至今已四百多年

Surprised to see black dots creeping over the surface  伽利略惊讶地发现，太阳表面有移动的黑点

he kept track of them over a number of days  因此连续观察了好几天

and found that they were all moving in the same direction.  结果发现它们都朝着相同的方向移动

To Galileo the meaning was clear  对伽利略而言，其意义再清楚不过

the sun was rotating  太阳在旋转

and was turning faster at the equator than at the poles.  而且赤道旋风的速度比两极快

It was a discovery that was to prove critical  这项发现对我们

in our understanding of how the sun works.  了解太阳的作用机制至关重要

Ever since Galileo records have been  自伽利略之后

kept of the coming and goings of sunspots  人们便开始记录太阳黑子的出现与消失

and variations soon became clear.  其变异很快就呼之欲出

Sometimes the sun is covered in hundreds of spots  有时太阳表面出现数以百计的黑子

other times there are none at all.  有时连一个都没有