Earth, Moon, and | Class 7 Science Notes

12.1 Rotation of the Earth

This section explains the concept of Earth's rotation and how it causes the apparent movement of the Sun from East to West, leading to day and night. It begins by relating the observation that the Sun rises in the East and sets in the West to the Earth's rotation. To help visualize this, the section introduces the analogy of a merry-go-round. When a person sits on a merry-go-round turning anti-clockwise, objects outside appear to move clockwise. This helps students understand that the apparent motion of the Sun is due to the Earth's rotation on its own axis, not the Sun moving around the Earth. The Earth rotates about an imaginary line called its axis, which passes through the geographic North and South Poles. The Earth completes one rotation approximately every 24 hours. When viewed from above the North Pole, the Earth rotates anti-clockwise, i.e., from West to East. Using a globe, students can simulate this rotation and observe how locations move around the axis. The section also explains that half of the Earth faces the Sun and experiences daytime, while the other half is in darkness, experiencing night. The rotation from West to East causes the Sun to appear to rise in the East and set in the West. This section includes several activities using a globe and torchlight to demonstrate day and night and the direction of Earth's rotation.

📊 Diagram: Fig. 12.1 shows a girl on a merry-go-round observing objects around her. Fig. 12.2 shows examples of spinning objects: a top, a fan, and a ball. Fig. 12.3 illustrates Earth's rotation on its axis. Fig. 12.4a shows a globe with a sticker marking a location, and Fig. 12.4b shows a globe illuminated by a torchlight to demonstrate day and night. Fig. 12.5 depicts sunlight falling on half of the Earth's surface.

🧪 Activity: Activity 12.1: Observing apparent motion on a merry-go-round. Activity 12.2: Using a globe and torchlight to understand Earth's rotation and day-night cycle.

🔗 Connection: Prepares for the next section on the apparent motion of the Sun and stars due to Earth's rotation and introduces the concept of revolution.