Earth
Defintion:
Earth is the planet where we live. It is the third planet from the Sun and the only known planet that has life.
Main Points :
Life-friendly planet – Earth has air, water, and the right temperature for living things.
Water planet – About 71% of Earth is covered with water.
Atmosphere – Earth has a layer of air that protects us and helps us breathe.
Gets energy from the Sun – Sunlight gives heat and light.
One natural satellite – Earth has one Moon.
Layers of the Earth :
Crust – The outer layer where we live
Mantle – Thick layer below the crust
Core – Very hot center of the Earth
1. Shape & Size:
Earth is almost a sphere (slightly flattened at the poles)
Diameter: about 12,742 km
Circumference: about 40,075 km
2. Layers of Earth:
Crust – outer layer where we live; made of rocks and minerals
Mantle – thick middle layer; solid but flows slowly
Outer Core – hot liquid layer of iron and nickel; creates magnetic field
Inner Core – solid, extremely hot; mostly iron and nickel
3. Atmosphere:
Layer of air around Earth
Protects us from Sun’s harmful rays
Made of nitrogen, oxygen, and other gases
4. Water on Earth:
About 71% of Earth is covered with water
Oceans, rivers, and lakes support life
5. Movement of Earth:
Rotation – Earth spins on its axis → causes day and night
Revolution – Earth moves around the Sun → causes seasons
6. Magnetic Field:
Created by the movement of the outer core
Protects Earth from harmful solar radiation
7. Life on Earth:
Earth is the only known planet with life
Supports plants, animals, humans, and microbes
Fun Fact:
The highest point is Mount Everest; the lowest is Mariana Trench