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Our Universe - The Sun and the Solar System

Grade 3ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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The Universe is a vast space that contains all heavenly bodies like stars, planets, and moons.

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The Sun is a medium-sized star at the center of our solar system. It is a giant ball of hot gases, primarily Hydrogen and Helium, providing heat and light energy (EE).

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The Solar System consists of the Sun and eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

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Rotation is the spinning of the Earth on its own axis. This movement causes day and night and takes 2424 hours to complete one full turn.

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Revolution is the movement of the Earth around the Sun in a fixed path called an orbit. This causes the change in seasons and takes approximately 36514365 \frac{1}{4} days.

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

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Venus is known as the 'Morning Star' or 'Evening Star' and is the hottest planet in our solar system because of its thick atmosphere.

📐Formulae

1 Rotation=24 hours=1 Day1 \text{ Rotation} = 24 \text{ hours} = 1 \text{ Day}

1 Revolution≈36514 days=1 Year1 \text{ Revolution} \approx 365 \frac{1}{4} \text{ days} = 1 \text{ Year}

Earth’s Distance from Sun≈150,000,000 km\text{Earth's Distance from Sun} \approx 150,000,000 \text{ km}

💡Examples

Problem 1:

If the Earth takes 2424 hours for one rotation, how many hours will it take to complete 33 rotations?

Solution:

24×3=7224 \times 3 = 72 hours.

Explanation:

Since one rotation equals one day (2424 hours), three rotations equal three days, which is 7272 hours.

Problem 2:

Which planet is known as the 'Red Planet' and why?

Solution:

Mars.

Explanation:

Mars is called the Red Planet because its surface is covered with red dust and rocks containing iron oxide (Fe2O3Fe_2O_3).

Problem 3:

Identify the largest and smallest planets in our solar system.

Solution:

Largest: Jupiter; Smallest: Mercury.

Explanation:

Jupiter is the 5th5^{th} planet from the Sun and is the most massive, while Mercury is the 1st1^{st} planet and is the smallest in size.