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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

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

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).

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

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.

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.

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

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 Revolution36514 days=1 Year1 \text{ Revolution} \approx 365 \frac{1}{4} \text{ days} = 1 \text{ Year}

Earth’s Distance from Sun150,000,000 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.