经济学人下载:太阳物理学 落山的太阳

Science and technology
科学技术

Solar physics
太阳物理学

Sun down
落山的太阳

Several lines of evidence suggest that the sun is about to go quiet
证据的一些方式表明太阳即将变平静

spots of bother?
太阳黑子的困扰？

DURING the four centuries that it has been studied in detail, the sun has usually behaved in a regular manner.
太阳已被详细研究了四百年，它通常以规则的方式反应。

The number of spots on its surface has waxed and waned in cycles that last, on average, 11 years.
太阳表面的黑子数在其一般延续11年的活动周期内增增减减。

Such cycles begin with spots appearing in mid-solar latitudes and end with them near the equator.
这样的周期活动以太阳黑子在其中纬度出现开始并随着黑子移动到赤道附近而终结。

And the more spots there are, the more solar storms there are around.
而且太阳黑子的数目越多，周围就会有越多的太阳风暴。

Sometimes, though, the sun sulks and this solar cycle stops.
然而，太阳有时也会生气，之后这种太阳活动周期就停止了。

That has happened twice since records began:
自从对这种太阳活动周期有记载以来，这种现象已经发生了两次了：

during the so-called Maunder minimum of 1645 to 1715 and the Dalton minimum of 1790 to 1830.
就是所称的1645年至1715年蒙德极小期和1790年至1830年道尔顿极小期期间。

These coincided with periods when global temperatures were lower than average, though why is a matter of debate.
这些现象与全球气温低于平均水平时相一致，虽然这是为什么争议的一个问题。

An absence of sunspots also means an absence of solar flares and their more violent siblings, coronal mass ejections.
缺少太阳黑子也意味着太阳耀斑以及它们更强烈的同胞-日冕物质抛射的不存在。

Such outbursts disrupt radio and satellite communications, electricity grids and a variety of electronic equipment, so the pattern of solar activity is of more than academic interest.
这种大爆发会干扰无线电和卫星通信，电网和各种电子设备，因此太阳活动方式超越了学术兴趣。

A new solar minimum, then, would test theories about how the climate works and also make communications more reliable.
然而，一个新的太阳极小期将会测试关于气候如何起作用的理论以及还将使得通信更加可靠。

And many solar physicists think such a new minimum is on the cards.
而且许多太阳物理学家认为这样一个新的太阳极小期很可能发生。

A group of them, who all work for America's National Solar Observatory, have just had a meeting in New Mexico, under the aegis of the American Astronomical Society, to announce their latest results.
在美国天文学会的主持下，美国国家太阳天文台工作的一群太阳物理学家刚刚在新墨西哥州举行了一次会议来宣布他们的最新成果。

Frank Hill and his team were the discoverers, 15 years ago, of an east-west jet stream in the sun.
弗兰克·希尔和他的研究小组就是15年前太阳内东西高速气流的发现人员。

They also worked out that the latitude of this wind is related to the sunspot cycle.
他们还计算出这次太阳风的纬度和太阳黑子的活动周期相关。

At the beginning of a cycle the jet stream is found, like sunspots, in mid-latitudes.
在一个活动周期开始的时候，就可以找到高速气流，像中纬度地区的太阳黑子。

As the cycle progresses, it follows the spots towards the equator.
随着活动周期的进展，高速气流随着太阳黑子向太阳的赤道方向移动。

Intriguingly, however, Dr Hill's studies indicate that the jet stream of a new cycle starts to form years before the sunspot pattern.
然而，让人感兴趣的事情是，希尔博士的研究表明一个新太阳活动周期的高速气流在太阳黑子活动方式前开始形成。

This time, that has not happened.
这次，高速气流还未产生。

History suggests a new cycle should begin in 2019.
历史表明一个新太阳活动周期应该开始于2019年。

If the sun were behaving itself, Dr Hill's team would have seen signs of a new jet stream in 2008 or 2009.
假如太阳自我反应的话，希尔博士研究人员在2008年或2009年早已观察到新高速气流的迹象了。

They did not.
但是他们没有看到这些情况。

Nor are there indications of one even now.
即使现在，也没有一个迹象出现。

If a change in the jet stream really is a leading indicator of solar activity, then no new cycle is on the horizon.
如果高速气流的变化真地是太阳活动最重要的指示物，那么新的太阳活动周期还未露端倪。

The second study which suggests something odd is happening looked at the strengths of sunspots.
表明奇怪的事情正在发生的第二项研究检查了太阳黑子的活力。

Matthew Penn and William Livingston have analysed 13 years of data which indicate that, independently of the number of spots around, there has been a decrease in their strength.
马修·佩恩威廉·利文斯敦已独立见解地分析了大致太阳黑子数的13年的数据表明这些黑子的活力已经下降了。

Sunspots are caused by irruptions into its surface of the sun's deeper magnetism.
太阳黑子是由入侵活动进入太阳深层磁性表面造成的。

These create local drops in temperature, which make the surface gas darker.
这些入侵活动导致了局部气温下降，使得太阳表面气体颜色更深。

Over the period which Dr Penn and Dr Livingston analysed, the average magnetic strength of the irruptions has declined.
佩恩和利文斯顿博士分析表明，入侵活动的平均磁场强度已有所下降。

Below a certain threshold, they will not be strong enough to overcome the convective mixing of the gas at the surface, and spots will disappear altogether.
低于一定的临界值的话，它们将不足以克服表面气体的对流混合，因而太阳黑子将完全消失。

If the present trend continues, that will happen in 2021.
如果目前的趋势继续下去，那么2021年太阳黑子就会消失。

The third measure of the sun's decline is in its outer atmosphere, the corona.
太阳衰落的标准就是其外层的气体日冕。

At each solar maximum, the corona sloughs off the magnetic fingerprint of the previous cycle by pushing it to the poles.
在每次太阳极大期，日冕通过把气体推向两极而使前一活动周期的磁性特征消退掉。

According to Richard Altrock, the leader of another NSO team at the meeting, that does not appear to be happening in the present cycle.
根据会议上美国国家太阳天文台的另一研究组的领导理查德·阿尔乔克所说，目前的太阳活动周期那种现象没有出现。

It looks, then, as if a new, extended solar minimum is about to begin.
然而，看上去好像一个新延续的太阳极小期将要开始。

That is good news for operators of communications satellites.
对通信卫星的经营者来说，这是好消息。

And it is interesting news for those who worry about global warming.
而且这对那些担心全球气温变暖的那些人来说是个令人有趣的新闻。

If the Maunder and Dalton minima actually did affect the climate,
如果蒙德和道尔顿极小期确实影响了气候，

then a new one might counteract the effects of the extra greenhouse gases people are now pumping into the atmosphere—at least, until the solar cycle returns.
那么新的太阳活动极小期可能抵消人们现在大量释放到空气中额外温室气体的影响-至少要到太阳活动周期恢复时。

Whether the breathing space thus granted would be used wisely or squandered is another matter.
无论是如此承认的呼吸空间会被明智地使用还是被大手大脚地挥霍掉将是另一回事。

Do not expect that debate to be as placid as the spotless sun.
不要指望辩论就像一尘不染的太阳那么宁静安详。