十万个为什么·科学阅读30篇（1）
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What Causes the Northern Lights to Dance Across the Sky?
是什么让北极光在夜空中舞动？
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The Northern Lights, or auroras, happen when charged particles from the Sun hit Earth’s upper atmosphere.北极光（极光）是太阳带电粒子撞击地球高层大气时产生的现象。
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These solar winds travel along magnetic field lines and concentrate near the North and South Poles.这些太阳风沿磁场线传播，并在南北两极附近聚集。
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When particles strike oxygen and nitrogen atoms, they excite electrons, which then emit light as they calm down.当粒子撞击氧原子和氮原子时，会激发电子；电子回落时便释放出光芒。
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Green light comes from oxygen at lower altitudes, while red and purple appear higher up or during strong storms.绿色光芒来自低空的氧原子，而红色和紫色则出现在更高处或强烈风暴期间。
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Magnetic reconnection—sudden shifts in Earth’s magnetic field—makes the lights flicker and swirl rapidly.磁重联——地球磁场的突然变化——使极光快速闪烁、旋转。
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Auroras follow an 11-year solar cycle, growing brighter and more frequent near solar maximum.极光遵循11年太阳周期，在太阳活动极大期时变得更亮、更频繁。
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Cameras capture movements too fast for our eyes, revealing waves, curls, and even 'auroral flames'.相机能捕捉人眼无法分辨的快速运动，展现出波浪、卷曲，甚至‘极光火焰’。
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Scientists use satellites and ground stations to predict aurora visibility days in advance.科学家利用卫星和地面观测站，可提前数天预测极光可见性。
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This cosmic light show links our planet directly to the Sun’s explosive energy output.这场宇宙光影秀将地球与太阳剧烈的能量输出直接联系起来。
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Watching the aurora reminds us that space weather shapes what we see—even from our own backyard.观赏极光提醒我们：空间天气塑造着我们所见的一切——哪怕就在自家后院。