Why do stars twinkle?
星星为什么会闪烁？
Look up at the sky on a clear night in a dark area, and the stars appear to twinkle. The concept is so well established that it's the premise of one of the most popular children's songs of all time.
在一个晴朗的夜晚，在黑暗的区域仰望天空，星星似乎在闪烁。这个概念是如此的成熟，以至于它是有史以来最受欢迎的儿歌之一的前提。
But what's the science behind this sparkly sight? What is it about stars that makes them twinkle?
但这一闪闪发光的景象背后的科学依据是什么？是什么使得星星闪烁？
It turns out, "twinkle, twinkle, little star" is a bit of a misnomer.
原来，“一闪一闪亮晶晶”有点用词不当。
Related: 15 unforgettable images of stars (opens in new tab)
相关：15个令人难忘的关于星星的印象（在新标签中打开）
The honest answer to why stars twinkle is that they don't. The twinkling we see has nothing to do with the stars themselves. Rather, it's a result of how we see them from our perspective on Earth.
对于星星为什么会闪烁，真正的答案是星星并不会闪烁。我们看到的闪烁与星星本身毫无关联。相反，这是我们从地球上的角度看待它们的结果。
Because stars are so far away, we see them as tiny points of light in the night sky.
因为星星离我们太遥远了，所以我们会把它们看成夜空中的微小光点。
"Starlight travels a great distance to reach our eyes on a clear night," said Ryan French, a solar physicist at University College London in the U.K. After our own star, the sun — whose average distance to Earth is 93 million miles (150 million kilometers) — the nearest star to us is Proxima Centauri, which is over 4 light-years from Earth.
英国伦敦大学学院的太阳物理学家瑞安·弗伦奇说：“在晴朗的夜晚，星光会传播很远的距离才能到达我们的眼中。”在我们自己的恒星——太阳——它到地球的平均距离是9300万英里（1.5亿公里）——之后，距离我们最近的恒星就是比邻星，它距离地球超过4光年。
On the way to our eyes, this light from distant stars encounters Earth's atmosphere — the key driver behind the twinkling effect.
在到达我们眼睛的过程中，这束来自遥远恒星的光与地球的大气层相遇——这是闪烁效应背后的关键驱动力。
"As this point of light reaches the atmosphere, it passes through layers of wobbling air before reaching our eyes, causing it to twinkle," French said.
弗伦奇说：“当这一光点到达大气层时，它在到达我们的眼睛之前会穿过一层层晃动的空气，这使得它闪烁。”
So it's Earth's wobbling atmosphere that makes stars appear to twinkle. In space, high above the atmosphere, stars don't twinkle at all. (That's one reason why the Hubble Space Telescope was sent into orbit: It could get sharper images of space without the images being distorted by atmospheric turbulence.)
所以，正是地球晃动的大气层使恒星看起来在闪烁。在大气层上方的太空中，恒星根本不会闪烁。（这就是哈勃太空望远镜被送入轨道的原因之一：它可以获得更清晰的太空图像，而不会因大气湍流而扭曲图像。）
Many factors affect how much a star appears to twinkle. One variable is the star's place within our field of view.
许多因素会影响一颗恒星闪烁的程度。其中一个变量就是恒星在我们视野中的位置。
"Stars will twinkle more if their starlight travels through more air before reaching our eyes," French said, so stars near the horizon appear to twinkle more because their light has to journey through more atmosphere to get to us.
弗伦奇说：“如果恒星的星光在到达我们的眼睛之前穿过更多的空气，那么它们就会闪烁得更多。”因此，地平线附近的恒星似乎闪烁得更多，因为它们的光必须穿过更多的大气才能到达我们的眼睛。
Weather also plays a role. "Humid nights will also cause the air to be thicker," making stars appear to twinkle more, French said.
天气也起了一定作用。弗伦奇说：“潮湿的夜晚也会导致大气变厚，”这使得星星看起来更加闪烁。
These issues help guide astronomers when they are deciding where to place the world's biggest and best telescopes. "Observatories are placed in high, dry places, to remove as much air between the star and telescope as possible," French said.
这些问题有助于指导天文学家决定在哪里放置世界上最大最好的望远镜。弗伦奇说：“天文台被放置在高处干燥的地方，以尽可能多地排出恒星和望远镜之间的空气。”
Ideal spots include the bone-dry Atacama Desert in Chile, as well as the volcanic peaks of Hawaii and the Spanish Canary Islands. These locations are examples of places with what astronomers refer to as good "seeing." "Thick air, causing a lot of wobble or twinkle, is bad seeing, whereas dry, calm and thin air creates good seeing."
理想的放置点包括智利及其干燥的阿塔卡马沙漠，以及夏威夷和西班牙加那利群岛的火山峰。这些位置是天文学家称之为“视觉良好”的地方的例子。“浓密的空气会引起很多晃动或闪烁，这是不好的视觉效果，而干燥、平静和稀薄的空气则会产生良好的视觉效果。
When you look up at the night sky, you may also notice that some stars appear to shift between different colors as they twinkle. Sirius, the brightest star in Earth's night sky, is a classic example.
当你抬头仰望夜空时，你可能还会注意到一些星星在闪烁时似乎会在不同的颜色之间变换。天狼星，在地球夜空中看到的最亮的恒星，就是一个典型的例子。
"Starlight gets refracted [bent] by the atmosphere a little bit, which can cause it to change color," French said. This effect is more noticeable with brighter stars.
弗伦奇说：“星光会被大气稍微折射[弯曲]，这可能会导致它变色。”这种效应在较亮的恒星中更为明显。
You may also notice a few "stars" that don't twinkle at all. That's because they are actually planets. "Unlike stars, planets are not point sources in the sky, but have width," French said. "This is because they are far closer to us." In other words, they are too big in the night sky for the atmosphere to make them appear to twinkle.
你可能还会注意到一些根本就不闪烁的“星星”。那是因为它们实际上是行星。“不同于恒星，行星不是天空中的点源，它们是有宽度的，”弗伦奇说。“这是因为行星离我们要近得多。”换句话说，它们在夜空中太大，因此大气无法使它们看起来闪烁。
However, if you look at the planets, or even the moon, through a telescope, you'll still see them appear to shimmer, as the light you're seeing has been jostled by the atmosphere on its way to your eyes.
然而，如果你通过望远镜观察行星，甚至月球，你仍然会看到它们似乎在闪烁，因为你看到的光在到达你眼睛的过程中经受了大气层的冲撞。
Original article on Live Science. (opens in new tab)
关于生活科学的原创文章。（在新选项卡中打开）
