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Chapter 12. Earth, Moon and the Sun

Chapter 12: Earth, Moon and the Sun

Definitions:

Rotation: Rotation is the movement of the Earth on its axis.

Revolution: Revolution is the movement of the Earth around the Sun in its orbit.

Axis: Axis is an imaginary line passing through the centre of the Earth.

Orbit: Orbit is the path followed by the Earth while revolving around the Sun.

Day and Night: Day and night are caused due to the rotation of the Earth.

Seasons: Seasons are caused due to the tilt of the Earth’s axis and its revolution around the Sun.

Satellite: A satellite is a body that revolves around a planet.

Moon: The Moon is the natural satellite of the Earth.

Phases of the Moon: The different shapes of the Moon seen from Earth are called phases of the Moon.

Constellation: A constellation is a group of stars forming a pattern in the sky.

Pole Star: The Pole Star is a star that appears fixed in the sky and helps in finding direction.

Solar Eclipse: A solar eclipse occurs when the Moon comes between the Earth and the Sun.

Lunar Eclipse: A lunar eclipse occurs when the Earth comes between the Sun and the Moon.

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Quick Revision Points:

• Earth rotates on its axis causing day and night.
• Earth revolves around the Sun causing seasons.
• The Moon is the Earth’s natural satellite.
• The Moon reflects sunlight.
• Phases of the Moon repeat every month.
• Stars are self-luminous bodies.
• Constellations form patterns in the sky.
• Pole Star helps in finding north direction.
• Solar eclipse occurs during new moon.
• Lunar eclipse occurs during full moon.
• Eclipses are natural phenomena.

Chapter 12. Earth, Moon and the Sun

Chapter 12: Earth, Moon and the Sun

Introduction: The Earth, Moon, and the Sun are important members of our solar system. Their movements and positions are responsible for many natural phenomena such as day and night, seasons, and eclipses.

Understanding their relationship helps us explain how time, seasons, and changes in the sky occur.

This chapter covers the following topics:

• Rotation and revolution of Earth
• Day and night
• Seasons
• Phases of the Moon
• Eclipses (solar and lunar)
• Stars and constellations (basic idea)

Earth’s Rotation: The Earth rotates on its axis from west to east. One complete rotation takes about 24 hours.

This rotation is responsible for the occurrence of day and night.

Example: When a part of the Earth faces the Sun, it experiences day, while the opposite side experiences night.

Earth’s Revolution: The Earth revolves around the Sun in an orbit. One complete revolution takes about 365 days.

This movement is responsible for the change of seasons.

Seasons: Seasons are caused due to the tilt of the Earth's axis along with its revolution around the Sun.

• Summer
• Winter
• Rainy season

Key Point: Rotation causes day and night, while revolution causes seasons.

The Moon: The Moon is the natural satellite of the Earth. It does not have its own light but reflects the light of the Sun.

The Moon revolves around the Earth and also rotates on its own axis. It takes about 27 days to complete one revolution.

Example: The shining Moon we see at night is actually reflecting sunlight.

Phases of the Moon: The Moon appears to change its shape every night. These different shapes are called phases of the Moon.

• New Moon (Amavasya)
• First Quarter
• Full Moon (Purnima)
• Last Quarter

This cycle repeats every month.

Why Phases Occur: Phases of the Moon occur because of the changing positions of the Earth, Moon, and Sun.

Only the part of the Moon that reflects sunlight is visible to us, and this changes as the Moon moves around the Earth.

Stars and Constellations: Stars are huge celestial bodies that emit their own light. They appear small because they are very far away.

Groups of stars forming recognizable patterns are called constellations.

Example: The Big Dipper (Saptarishi) is a well-known constellation.

Pole Star: The Pole Star appears to remain fixed in the sky. It is located near the axis of the Earth.

It is useful for finding directions, especially the north direction.

Key Point: The Moon reflects sunlight, and stars are self-luminous bodies forming patterns called constellations.

The Moon: The Moon is the natural satellite of the Earth. It does not have its own light but reflects the light of the Sun.

The Moon revolves around the Earth and also rotates on its own axis. It takes about 27 days to complete one revolution.

Example: The shining Moon we see at night is actually reflecting sunlight.

Phases of the Moon: The Moon appears to change its shape every night. These different shapes are called phases of the Moon.

• New Moon (Amavasya)
• First Quarter
• Full Moon (Purnima)
• Last Quarter

This cycle repeats every month.

Why Phases Occur: Phases of the Moon occur because of the changing positions of the Earth, Moon, and Sun.

Only the part of the Moon that reflects sunlight is visible to us, and this changes as the Moon moves around the Earth.

Stars and Constellations: Stars are huge celestial bodies that emit their own light. They appear small because they are very far away.

Groups of stars forming recognizable patterns are called constellations.

Example: The Big Dipper (Saptarishi) is a well-known constellation.

Pole Star: The Pole Star appears to remain fixed in the sky. It is located near the axis of the Earth.

It is useful for finding directions, especially the north direction.

Key Point: The Moon reflects sunlight, and stars are self-luminous bodies forming patterns called constellations.

Chapter 12. Earth, Moon and the Sun

Chapter 12: Earth, Moon and the Sun – Assignments

1 Mark Questions:

Q1. What is rotation?

Q2. What is revolution?

Q3. What is an axis?

Q4. What is an orbit?

Q5. What is a satellite?

Q6. What is the Moon?

Q7. What are phases of the Moon?

Q8. What is a constellation?

Q9. What is the Pole Star?

Q10. What is a solar eclipse?

2 Marks Questions:

Q1. Define rotation with an example.

Q2. Define revolution with an example.

Q3. What causes day and night?

Q4. What causes seasons?

Q5. What is the Moon? Why does it shine?

Q6. What are phases of the Moon? Explain briefly.

Q7. What are constellations? Give one example.

Q8. What is the importance of the Pole Star?

Q9. What is a solar eclipse?

Q10. What is a lunar eclipse?

3 Marks Questions:

Q1. Explain rotation and revolution of the Earth.

Q2. Describe the causes of day and night.

Q3. Explain how seasons are formed.

Q4. Describe phases of the Moon in detail.

Q5. Explain solar and lunar eclipses.

Q6. Describe constellations and their importance.

Q7. Explain the role of the Moon in our life.

Q8. Describe the relationship between Earth, Moon, and Sun.