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太阳那么热,为什么太空却很冷

If The Sun Is Hot, How Is Outer Space Cold?

“If the sun is hot how is outer space cold ?”
“太阳那么热 为什么外太空却很冷?”
Excellent question, Jacoby Brissett, current quarterback of the Indianapolis Colts.
雅各比·布里塞特问得好 他目前是印第安纳波利斯小马的四分卫
It turns out that outer space is full of extreme temperatures.
实际上外太空的温度都很极端
The sun is a ball of gas and fire
太阳就是一个由气体组成的火球
measuring around 27 million degrees Fahrenheit at its core and 10,000 degrees at its surface.
中心温度约为1500万度 表面温度约为5500度
Meanwhile, the cosmic background temperature—that is, the average temperature of outer space—
但是宇宙温度 也就是外太空平均温度
hovers at negative 455 Fahrenheit.
在零下270度左右波动
Heat from the sun travels through the cosmos as radiation, an infrared wave of energy.
太阳的热量通过载有能量的红外波辐射到宇宙中
Those waves excite molecules they come into contact with, causing them to heat up.
红外波影响它经过的分子 并使它们升温
The catch is that radiation only heats molecules and matter that are directly in its path.
重点是辐射只能加热它穿过的分子或物体
Everything else stays chilly.
其余的都不能被加热
That’s why the nighttime temperatures on the planet Mercury
这也是为什么美国宇航局的数据显示
can be 1,000 degrees Fahrenheit lower than the radiation-exposed day side, according to NASA.
水星晚上的温度比白天有阳光直射的地方低了540度
Earth’s atmosphere helps to distribute that solar radiation through three methods:
地球大气有三种方法分散太阳辐射
conduction, convection, and radiation.
传导 对流和辐射
When the sun’s radiation hits and warms up molecules in our atmosphere,
当太阳辐射接触并加热大气层中的分子时
they pass that extra energy on to the molecules around them.
它们把多余的能量传递给周围的分子
Those molecules then bump into and heat up their own neighbors.
这些分子又会通过相互碰撞 将热量传递给其它分子
This heat transfer from molecule to molecule is called “conduction,”
这种分子与分子之间的热量传递叫做传导
and it’s a chain reaction that warms areas outside of the sun’s path.
这种连锁过程使太阳直射外的地方也能变暖
Space, however, is a vacuum—meaning it’s basically empty.
但太空是真空的 基本上什么都没有
Gas molecules in space are too few and far apart to regularly collide with one another.
气体分子不仅稀少而且相距很远 因而很难发生碰撞
So even when the sun heats them up with infrared waves,
所以即使它们被太阳的红外波加热
transferring that heat via conduction isn’t possible.
也很难把热量传导出去
Similarly, convection—a cycle where air gets less dense and rises as it heats up,
同样 对流――空气受热后密度降低而上升 受冷后密度增大而下降的循环
and then sinks and gets more dense as it cools— is important for dispersing warmth across the Earth.
对地球上热量的分散也十分重要
But in the zero-g vacuum of space, it simply can’t happen.
但在没有重力的真空中 这是不可能发生的
The extreme temperature differentials of space present unique challenges to the missions
对世界各地的航天机构来说
conducted by space agencies around the world.
宇宙中的极端温差是特殊的挑战
In April 2019, NASA’s Parker Solar Probe was 15 million miles away from the Sun.
2019年4月 美国宇航局的帕克太阳探测器距太阳2400万千米
That’s closer than any other spacecraft in history.
是历史上离太阳最近的宇宙飞船
The probe’s heat shield protected its internal parts from temperatures around 250 degrees Fahrenheit,
用于保护探测器内部构件的隔热板 在面对121度的高温的同时
while the back side was simultaneously experiencing temperatures of negative 238 degrees Fahrenheit.
还要应对背面零下114度的温度
Preparing for temperature shifts of hundreds of degrees might sound wild,
要应对上百度的温度变化可能很疯狂
but it’s just how things are out in space.
但这只发生在太空中
Plot twist: the real oddity is Earth.
剧情转折:真正怪异的其实是地球
Amidst the extreme cold and fiery hot, our atmosphere keeps things surprisingly mild—
我们的大气层在极冷与极热交融中保持着温暖
at least for now.
至少目前可以

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视频概述

太阳的能量通过红外波传递,地球大气将这些能量分散,维持地球表温度

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视频来源

https://www.youtube.com/watch?v=za-Zf1nB418

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