Get ready to explore how Earth moves! This chapter is all about two important things it does: spinning around (rotation) and going in a big circle around the sun (revolution). These movements make day and night happen and bring us different seasons. Let's dive into the exciting world of the "Motions of the Earth" and discover how these dances in the sky shape our world!
Motions of Earth
Earth exhibits two primary motions: rotation and revolution.
Earth's Rotation and Revolution
Revolution: Revolution is the earth's movement around the sun in a fixed orbit, taking approximately 365¼ days to complete one full revolution (a year).
Inclination of Earth's Axis and the Orbital Plane
Earth's rotation on its axis creates the day-night cycle.
Circle of Illumination
Earth's revolution around the sun causes the change of seasons.
Earth's orbit around the sun is elliptical. Throughout its orbit, the earth is inclined in the same direction. Seasons change due to the tilt of the earth's axis. A year is typically split into four seasons: summer, winter, spring, and autumn.
Revolution of Earth and Change in Seasons
On 21st June, the Northern Hemisphere experiences the Summer Solstice, with the North Pole tilted towards the sun.
On 22nd December, the Southern Hemisphere experiences the Winter Solstice, with the South Pole tilted towards the sun.
On 21st March and September 23rd, the entire earth experiences equal days and nights, known as equinoxes.
Earth During Equinox
- Days, nights, and seasonal changes are a result of the earth's rotation and revolution.
- Understanding these motions is crucial for comprehending natural phenomena and the changing environment.
Q.1: Define rotation and revolution of the Earth.
Ans: Rotation: Movement of the Earth on its axis in nearly 24 hours is termed as rotation. It is also called the daily movement of the earth.
Revolution: Movement of the earth around the Sun on a fixed path or orbit is called revolution.
Q.2: What is the circle of illumination? Why does it not coincide with the axis of the Earth?
Ans: The circle which separates day from night is called the circle of illumination. The circle of illumination does not coincide with the axis of the Earth due to the planet's axial tilt. The Earth is tilted on its axis at an angle of approximately 23.5 degrees relative to its orbital plane around the Sun. This axial tilt is what causes the changing seasons on Earth.
Q.3: Distinguish between rotation and revolution.
Ans: The distinction between rotation and revolution is as under:
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1. What is the significance of Earth's rotation and revolution? |
2. How does Earth's axis and orbital plane affect its motions? |
3. What is the significance of the summer and winter solstice? |
4. What happens during an equinox? |
5. How do Earth's motions impact the length of day and night? |
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