03. Motions of the Earth class 6 Chapter 3 Geography – NCERT Notes for CBSE Estimated reading: 5 minutes 72 views Welcome to Motions of the Earth class 6 Chapter 3 Geography – NCERT Notes for CBSE. MOTIONS OF THE EARTH Introduction In this chapter, we will delve into the fascinating motions of our planet Earth. Earth’s movements are not limited to its static existence; instead, it engages in dynamic rotations and revolutions. These movements have profound effects on our daily lives and the changing seasons. Rotation: Earth’s Daily Spin Earth rotates on its axis, creating day and night. The axis of Earth forms a 66½° angle with its orbital plane. The circle dividing day from night is called the circle of illumination. It takes approximately 24 hours for Earth to complete one full rotation. This period is known as an “earthday.” Keywords and Definitions Rotation: The spinning motion of Earth around its own axis, leading to the alternation of day and night. Key Takeaway: Rotation Earth’s daily spin on its axis causes the cycle of day and night. Revolution: Earth’s Yearly Journey Earth revolves around the sun in a fixed orbit. It completes one full revolution in approximately 365¼ days. To simplify calculations, we consider a year as 365 days and add an extra day to February every fourth year, creating a leap year. Keywords and Definitions Revolution: The orbital motion of Earth around the sun, leading to the changing of seasons. Leap Year: A year with 366 days, including an extra day added to February every four years. Key Takeaway: Revolution Earth’s annual journey around the sun leads to the changing seasons. Tilted Axis and Seasons Earth’s axis remains inclined in the same direction throughout its orbit. Seasons change due to the varying angle of sunlight received on Earth’s surface. On 21st June, the Northern Hemisphere tilts toward the sun, experiencing summer. The Southern Hemisphere experiences winter at this time. On 22nd December, the Tropic of Capricorn receives direct sunlight, leading to summer in the Southern Hemisphere and winter in the Northern Hemisphere. 21st March and 23rd September are equinoxes when day and night are nearly equal worldwide. Keywords and Definitions Tilted Axis: Earth’s axis is tilted in a specific direction relative to its orbital plane, causing seasonal variations. Equinox: A point in Earth’s orbit where day and night are nearly equal in duration. Key Takeaway: Tilted Axis and Seasons The tilt of Earth’s axis causes the changing seasons across the globe. Effects of Earth’s Motions The rotation of Earth results in the alternation of day and night, essential for life. The revolution around the sun creates different seasons, influencing temperature and climate. Earth’s motions impact the length of days, nights, and the intensity of sunlight. motions of the earth class 6. Frequently Asked Questions (FAQs) 1. What is the angle of inclination of Earth’s axis with its orbital plane? Earth’s axis forms an angle of 66½° with its orbital plane. 2. Define rotation and revolution. Rotation: The spinning motion of Earth around its own axis, leading to the alternation of day and night. Revolution: The orbital motion of Earth around the sun, leading to the changing of seasons. 3. What is a leap year? A leap year has 366 days, with an extra day added to February every four years. 4. How do the Summer and Winter Solstices differ? The Summer Solstice occurs when the Northern Hemisphere tilts toward the sun, resulting in summer there and winter in the Southern Hemisphere. The Winter Solstice is the reverse. 5. What is an equinox? An equinox occurs when neither pole is tilted toward the sun, resulting in nearly equal day and night worldwide. 6. Why do the Southern and Northern Hemispheres experience opposite seasons? The tilt of Earth’s axis causes one hemisphere to receive more direct sunlight while the other receives slanting rays, leading to contrasting seasons. 7. How do Earth’s motions affect day and night? Rotation causes the alternation of day and night, while revolution leads to variations in the length of daylight. 8. Why is there a need for leap years? Leap years, with an extra day added to February, compensate for the additional 0.25 days in Earth’s orbit, aligning our calendars with the astronomical year. 9. What causes the changing of seasons on Earth? The changing of seasons is primarily caused by Earth’s axial tilt, which results in variations in the angle and intensity of sunlight received in different parts of the world. 10. How do equinoxes differ from solstices? Equinoxes mark the moments when day and night are approximately equal in duration, occurring twice a year. Solstices, on the other hand, mark the longest and shortest days of the year, when the Northern or Southern Hemisphere is tilted most toward or away from the sun. Conclusion Earth’s motions, rotation, and revolution are fundamental to the existence of day and night, the changing seasons, and the diversity of climates across our planet. Understanding these movements enhances our appreciation of the natural world and the rhythm of life on Earth. This was the end of Motions of the Earth class 6 Chapter 3 Geography – NCERT Notes for CBSE. For more information, refer to NCERT SOLUTIONS, NCERT NOTES, and NCERT BOOKS .
