1. Unit 1: Earth Structures

2. Chapter 1: Earth’s Layers

3. Lesson 1: Spherical Earth

4. Describing Earth A sphere is shape like a ball, with all points on the surface at an equal distance from the center. Earth systems: – Atmosphere: layer of gases – Hydrosphere: liquid water on Earth – Biosphere: all living organisms on Earth – Cryosphere: frozen water on Earth – Geosphere: Earth’s entire solid body

5. How did Earth form? Earth formed about 4.6 billions years ago (bya), along with the Sun and the rest of the solar system Gravity is the force that every object exerts on every other object because of their masses

6. The Formation of Earth’s Layers