穿过厚厚的糖浆，钻头越来越烫。前面就是地球的内心：一颗铁做的心脏：地核。Through the thick syrup, the drill grows hotter. Ahead lies Earth's heart: an iron heart called the core.
第 1 步：外面是汤，里面是球Step 1: Soup outside, ball inside
先看清这颗心的结构——它分两层，完全不一样。First, see this heart clearly — it has two layers, totally different.
地核分两层：外核是流动的铁水，又烫又稠；内核是固态大铁球，被巨大压力压实了。两层都是铁和镍。The core has two layers: the outer core is flowing liquid iron, hot and thick; the inner core is a solid iron ball squeezed by huge pressure. Both are iron and nickel.
流动的铁水有什么用？它造出了保护我们的东西。What is flowing iron good for? It builds something that protects us.
第 2 步：看不见的保护罩Step 2: The invisible shield
外核铁水一流动，就造出了地磁场。它像保护罩，挡开太阳风。指南针跟着它指北，极光是它放的烟花。When outer-core iron flows, it builds the magnetic field. Like a shield, it blocks the solar wind. Compasses follow it north, and auroras are its fireworks.
可没人钻到过地核，我们怎么知道里面长这样？But nobody has drilled to the core — so how do we know what it looks like?
第 3 步：照进地球的手电Step 3: A flashlight into Earth
靠地震波！它像手电照进地球。有的波穿不过液体，一试便知外核是液态。内核烫得像太阳表面，约 5500℃。Thanks to seismic waves! They shine into Earth like a flashlight. Some waves stop at liquid — proof the outer core is liquid. The inner core burns like the Sun's surface, about 5500°C.
🎮 你来钻到地核（30 秒）🎮 Your turn: drill to the core (30 seconds)
从地表出发，逐层钻到地核；再答 4 道题，说出外核为什么重要。Start at the surface and drill layer by layer to the core; then answer 4 questions on why the outer core matters.
一句话记住它：地核是铁镍做的心脏，外液内固；外核流动造出磁场，保护着我们。Remember it in one line: the core is an iron-nickel heart, liquid outside and solid inside — the flowing outside builds the shield that protects us.
外核液态，内核固态，都是铁和镍Liquid outer core, solid inner core — both iron and nickel外核流动造出地磁场，指南针和极光都靠它The flowing outer core builds the field behind compasses and auroras地震波是手电，照出地球内部的样子Seismic waves are a flashlight revealing Earth's inside
内容参考 OpenStax 等公开教材，多来源核对 · AI 生成、人工审核 · 发现错误欢迎指正，帮这片叶子长得更好。Based on OpenStax and other open textbooks, cross-checked across sources · AI-generated, human-reviewed · Spotted a mistake? Tell us — help this leaf grow.
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