📗 Core (860~950) | What’s Happening Deep Inside the Earth?

지구 속 깊은 곳, 움직이는 액체가 지구를 지키고 있어요!
✔ 학습 목표 제시 (한글)
지구의 **핵(core)**에서 일어나는 움직임과 자기장(magnetic field) 생성 원리를 이해하고, 이 과정이 지구를 어떻게 보호하는지 알 수 있어요.

🔹 Reading Passage
At the center of our planet, there is a core made of hot, heavy metals like iron and nickel. The inner core is solid because it’s under so much pressure. The outer core, however, is liquid, and it moves slowly like thick soup.

This movement is called convection. Hot liquid iron rises, cools down, and sinks again, creating a constant cycle. As this liquid iron moves, it creates electric currents—and those currents make a magnetic field around the Earth. This process is known as the magnetic dynamo.

Think of it like a chocolate fountain. As the melted chocolate flows in circles, heat moves around and the fountain keeps working. Inside the Earth, the flowing metal works like a giant engine. It generates invisible magnetic energy that surrounds and protects our planet.

Why is this magnetic field so important? It shields the Earth from harmful radiation and strong solar winds coming from space. Without it, satellites could break, our communication systems could fail, and dangerous space particles could damage our atmosphere.

So where does all the heat come from? Scientists believe much of it is primordial heat—energy left over from when the Earth first formed about 4.5 billion years ago. That ancient heat is still escaping slowly and keeps the core in motion.

Thanks to this hidden power, the Earth’s core acts like a silent protector, working day and night to keep life on our planet safe.

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🔗 관련 개념 더 배우기:
The Earth’s Core and Magnetic Field 개념을 더 쉽게 배우고 싶다면 아래 콘텐츠도 참고해보세요.
👉 🌎 영어로 배우는 과학!｜The Earth’s Core and Magnetic Shield

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🔹 Reading Comprehension Question 1
Q1. What causes the Earth’s magnetic field?
A. The Moon’s gravity
B. The heat from sunlight
C. Moving liquid iron and electric currents
D. The solid part of the core

🔹 Reading Comprehension Question 2
Q2. Why is the magnetic field important for life on Earth?
A. It keeps Earth’s surface cool
B. It protects the Earth from harmful space radiation
C. It helps plants grow faster
D. It makes the atmosphere thicker

🔹 Vocabulary Quiz
Q3. What does “primordial heat” refer to?
A. Heat from the sun
B. Heat made by oceans
C. Heat left over from Earth’s formation
D. Heat from the Moon’s surface

🔹 Grammar Quiz
Q4. Choose the correct sentence using present perfect tense:
A. The core make heat for billions of years.
B. Scientists has studied the core since 2000.
C. The Earth has had a magnetic field for a long time.
D. Heat come from the outer layer only.

🔹 어휘 정리표 (TOP 10)

영어 단어	영어 뜻	한글 뜻	예문
core	center of something	핵, 중심	The Earth’s core is very hot and dense.
iron	a strong, heavy metal	철	Iron is a key part of the Earth’s core.
nickel	a silver-white metal	니켈	Nickel is often found with iron inside the Earth.
solid	firm, not liquid or gas	고체의	The inner core is solid because of high pressure.
liquid	flowing like water	액체의	The outer core is made of liquid iron.
convection	heat movement in fluids	대류	Convection moves heat in the liquid core.
electric current	a flow of electricity	전류	Electric currents in the core create a magnetic field.
magnetic field	invisible protective force	자기장	The Earth’s magnetic field protects us from radiation.
radiation	dangerous energy from space	방사선	The magnetic field blocks harmful radiation.
primordial heat	ancient leftover energy	원시열	Primordial heat helps keep the core hot.

✔ 정답 및 해설
Q1. 정답: C – Moving liquid iron and electric currents
→ The passage explains that electric currents from moving liquid iron create the magnetic field.

Q2. 정답: B – It protects the Earth from harmful space radiation
→ The text clearly says the magnetic field shields Earth from solar winds and radiation.

Q3. 정답: C – Heat left over from Earth’s formation
→ “Primordial heat” means leftover energy from when Earth first formed.

Q4. 정답: C – The Earth has had a magnetic field for a long time.
→ Present perfect = has/have + past participle. Only C fits this rule.

✅ Extra Grammar Note
Present perfect is used to show something that started in the past and continues now – 현재까지 영향을 주는 동작에 사용해요.

🔁 문법 복습 문제
Choose the correct sentence using present perfect:
A. The scientist have discover the Earth’s core.
B. The Earth has protect us for years.
C. The core has produced heat for billions of years.
D. The liquid core have make a shield.

정답: C
→ “has produced” is the correct present perfect form; subject “core” is singular.

💡 감성 마무리 문장
지구 깊은 곳에서 보이지 않게 흘러나오는 힘이, 우리 삶을 조용히 지켜주고 있어요.

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