Chapter-Chapter 12. Earth, Moon and the Sun Science Curiosity class 7 in english Medium CBSE Notes

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.

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