Keeping Time with the Skies | Class 8 Science Notes

The Earth’s Revolution and the Year

This section explains Earth's revolution around the Sun and how it defines the year. Earth takes approximately 365.25 days to complete one orbit around the Sun. This motion, combined with Earth's axial tilt of about 23.5 degrees, causes the changing seasons. The section describes the elliptical orbit of Earth and how the tilt causes varying sunlight angles and day lengths throughout the year. This variation leads to summer, winter, spring, and autumn in different parts of the world. The concept of a leap year is introduced to account for the extra 0.25 days each year, adding one extra day every four years to keep the calendar aligned with Earth's position. The section also explains how the position of the Sun in the sky changes with seasons, affecting temperature and climate.

📊 Diagram: Diagram showing Earth's elliptical orbit around the Sun with four marked positions representing different seasons. The tilt of Earth's axis is shown relative to the orbital plane.

🧪 Activity: Activity: Using a tilted globe and a lamp to simulate Earth's revolution and observe sunlight angles at different positions.

🔗 Connection: Prepares for the section on calendars and how time is organized based on Earth's motions.