评论
打印
If you've seen any pictures from the recent solar eclipse, you've probably noticed a big, wispy halo shining from behind the moon.
如果你看过最近日食的照片,你可能已经注意到月球背面闪耀着一个巨大微弱的光晕。
That's the corona, the outermost layer of the sun's atmosphere, and it's pretty sweet.
这是日冕，在太阳大气的最外层，它很酷。
It's also home to one of the biggest mysteries in astronomy.
它也是天文学上最大的谜题之一。
Even though the corona is the top layer of the sun's atmosphere, it's hundreds of times hotter than the surface.
尽管日冕在太阳大气的外层，但仍比太阳表面的温度高几百倍。
A whopping 1 to 4 million degrees celsius, compared to about 5500 degrees.
它的温度高达1至4百万摄氏度，而太阳表面只有5500度。
Astronomers have done enough research to give them some ideas why, but to really figure it out,
天文学家们已经做了足够多的研究猜想其原因，但为了真正弄清楚，
they're getting ready to send a probe into the fires of the sun itself.
他们正准备向太阳本身的火焰里发射探测器。
The corona is so thin that the rest of the sun's light usually outshines it,
日冕很稀薄，其余太阳光压过了它的光，
which is why you can only see it clearly from Earth during an eclipse.
这就是你只能在日食期间从地球上看清楚它的原因。
It's also enormous, extending millions of kilometers above the sun's surface.
它也很巨大，在太阳表面绵延数百万公里。
Like the rest of the sun, the corona is made of plasma,
和太阳的其余部分一样，日冕是由等离子体构成的，
which is basically a charged gas that forms when atoms become so hot that their electrons break free from their orbits.
等离子体基本上是一种带电气体，当原子变热时，它们的电子就会脱离轨道，等离子体由此形成。
For the corona to be as hot as it is, astronomers think there has to be some totally different kind of heating mechanism happening there,
因为日冕温度非常高，天文学家认为它上面有几种完全不同的加热机制发生。
because usually it gets colder the farther you get from a heat source.
因为通常情况下，离热源越远，温度越低。
One popular idea is that it involves wave heating,
一个流行的观点是，它涉及到电磁波加热，
where strong waves of energy are created by turbulence on the sun's surface and then travel out to the corona.
太阳表面的湍流形成强烈的能量波，然后它冲出日冕，
These waves move kind of like ocean waves, except that instead of water, there are ions and electrons in the plasma moving back and forth.
这种电磁波有点儿像海浪，只不过不是水，而是等离子体中来回移动的离子和电子。
And whenever those charged particles move, they also create a magnetic field.
无论什么时候这些带电粒子移动，都会产生磁场。
The field doesn't move exactly the same way as the particles,
磁场的移动与粒子不完全相同，
but it can change strength and direction as the wave travels, and the magnetism also gives the wave some extra energy.
但它可以改变电磁波的强度和方向，磁力也会给电磁波一些多余的能量。
According to this hypothesis, as the waves move away from the sun,
按照这个假设，当电磁波远离太阳时，
all that energy eventually turns into heat that makes the corona all nice and cozy.
所有的能量完全转化为热量，使日冕美好舒适。
But that still might not be enough to make the corona as hot as it is.
但这不足以使日冕达到如此高温。
In 2011, scientists studying the sun's transition zone, the region of the sun's atmosphere just below the corona,
2011年，科学家研究了太阳的过渡区，即日冕下面的大气层区域，
found wave heating could be enough to get the corona to the bottom of its temperature range—or about a million degrees Celsius.
发现电磁波加热能使日冕达到温控范围的底线，即大约一百万摄氏度。
But when there's a lot of solar activity, the corona can get up to four times hotter than that,
但有很多太阳活动时，日冕温度可以达到该温度值的四倍，
so something has to be causing the extra boost.
所以必须要有额外的动力。
To help explain it, astronomers have another hypothesis called magnetic reconnection,
为了解释这一点，天文学家们有了另外一个假设，叫做磁重联，
which happens when pockets of magnetism in the sun's plasma connect and release a ton of energy.
太阳等离子体中的一些磁力区域相连并释放大量能量时，就发生了磁重联。
These pockets are called magnetic domains, and they're regions where the magnetic fields line up so they're pointing in the same direction.
这些区域称为磁畴，它们是由磁场连接起来的指向相同的区域。
Here on Earth, this happens all the time when rocks or metals become magnetized,
在地球上，火箭或金属被磁化时会发生此种情况，
but because those domains are in solid materials, they don't interact in the same way.
但因为这些磁畴是固体材料，所以它们以不同的方式相互作用。
On the sun, because there's all that plasma swirling around, magnetic domains can come into contact with each other—
在太阳上，因为所有等离子旋转，磁畴之间就会相互作用，
and when they do, things get kinda weird.
因此，事情变得有点儿奇怪。
Usually, when magnetic fields combine, we can predict the outcome.
通常，磁场结合时，我们可以预测结果。
But with magnetic reconnection, there's all kinds of weird bending and stretching to throw off our calculations.
但随着磁重联的发生，有磁力线发生各种奇怪的弯曲和伸展，这超出我们的计算。
That's because there are a lot of other factors involved that we usually don't have to deal with on Earth,
这是因为有许多我们不曾在地球上涉及过的其它因素包含其中，
like the fact that the sun is rotating and plasma is moving around all over the place,
就像太阳旋转，等离子体到处移动一样，
which creates a constantly changing system we don't totally understand yet.
它们创造了一个不断变化的我们还不曾完全了解的系统。
One thing we do know is that, when two domains collide that were lined up in opposite directions,
我们知道，当两个磁畴相互碰撞以反方向排列时，
they annihilate each other and release a huge amount of heat energy,
它们互相湮灭，释放出大量的热量，
and that might be enough to boost the corona to those higher temperatures.
这可能足以使日冕提高到更高的温度。
We're not positive these two ideas explain everything, or even if that's really what's happening in the corona.
我们不能用这两种观点解释一切，即使这真的是日冕上正在发生的事情。
Instead, there might be a lot of smaller mechanisms we don't know about.
相反，日冕上可能有许多我们不知道的更小机制。
So togather more data, NASA is about to fly a probe into the sun!
所以，综合了更多的数据后，宇航局准备向太阳发射一枚探测器。
It's called the Parker Solar Probe, and it'll have a bunch of instruments to study things like coronal heating, magnetism, and plasma dynamics.
它叫做“帕克太阳探测器”，上面装载着许多设备来研究日冕加热、磁力和等离体动力等。
To get that data, the probe will fly within 6 million KMs of the sun which is closer than we've ever been before!
为了得到这些数据，探测器将在距太阳600万公里的范围内飞行，这比以前的距离更近。
The probe's SWEAP instrument, which stands for Solar Wind Electrons Alphas and Protons,
探测器的SWEAP（Solar Wind Electrons Alphas and Protons）设备，
will gather information on what's going on in the corona,
将会收集日冕活动的信息，
which, along with with tons of observations from the ground, will hopefully tell us why it's so hot!
再结合地球上的大量观测，我们有希望知道日冕高温的原因。
The Parker Solar Probe isn't scheduled to launch until summer 2018,
“帕克太阳探测器”计划在2018年夏天发射，
so we'll just have to hang tight until then—but maybe the next time a solar eclipse comes around, the corona won't be such a mystery.
到时我们会紧密关注，或许下次日食发生时，日冕就不会神秘了。
Thanks for watching this episode of SciShow Space!
感谢您收看本期的太空科学秀！
If you want to learn more about the Parker Solar Probe, you can watch our earlier episode where we give you all the details.
如果你想了解更多的“帕克太阳探测器”内容，你可以看我们的早期节目，里面有全部细节。
