Grade 6 I Natural Science and Technology I Movements of the Earth and Planets

Movements of the Earth and Planets
1. Types of Movements

a. Rotation
Definition: The spinning of the Earth on its axis.
Duration: Takes approximately 24 hours to complete one full rotation.
Effects:
Causes day and night.
The side facing the Sun experiences daytime, while the opposite side is in darkness (nighttime).
b. Revolution
Definition: The movement of the Earth around the Sun in an elliptical (oval) orbit.
Duration: Takes about 365.25 days to complete one full revolution.
Effects:
Causes the seasons (spring, summer, autumn, winter).
The tilt of the Earth's axis (approximately 23.5 degrees) affects the intensity and duration of sunlight received in different regions.
2. Earth’s Tilt and Seasons
The Earth's axis is tilted as it moves around the Sun.
This tilt causes varying angles of sunlight, leading to different temperatures and seasons in various parts of the world.
Summer: The hemisphere tilted toward the Sun experiences warmer temperatures and longer days.
Winter: The hemisphere tilted away from the Sun experiences cooler temperatures and shorter days.
Spring and Autumn: Transitional seasons with moderate temperatures.
3. Orbit
The Earth travels in a path around the Sun called an orbit.
The shape of the orbit is an ellipse, meaning it is slightly stretched rather than a perfect circle.
The distance between the Earth and the Sun varies throughout the year, but this does not significantly affect the seasons.
4. Other Planetary Movements
Other Planets: All planets in the solar system rotate on their axes and revolve around the Sun.
Each planet has a unique rotation period (day length) and revolution period (year length).
For example, Jupiter has a very short rotation period of about 10 hours, while Venus has a slow rotation period of about 243 Earth days.
5. Gravity
The force of gravity keeps the planets, including Earth, in orbit around the Sun.
Gravity pulls objects toward each other, which is why the Sun can hold all the planets in their orbits.
6. Phases of the Moon
The Moon also has its own movements:
Rotation: The Moon rotates on its axis.
Revolution: It revolves around the Earth.
The Moon takes about 27.3 days to orbit the Earth and about 29.5 days to go through all its phases (new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent).
7. Key Vocabulary
Axis: An imaginary line around which an object spins.
Orbit: The path an object takes as it moves around another object in space.
Ellipse: An elongated circle or oval shape.