CBSE Class 6 General Knowledge

Unit 4: Science & Technology

Lesson: Planets and Satellites

📘 Study Module: Planets and Satellites

1. Introduction

Planets and satellites are important members of the Solar System. They move in space under the influence of gravity. Studying them helps us understand the structure and functioning of the universe.

2. Meaning of Planets

Planets are large celestial bodies that revolve around the Sun in fixed paths called orbits. They do not have their own light and shine by reflecting sunlight.

3. Types of Planets

Planets are broadly classified into:

• Inner (Terrestrial) Planets: Mercury, Venus, Earth, and Mars
• Outer (Gaseous) Planets: Jupiter, Saturn, Uranus, and Neptune

Inner planets are rocky, while outer planets are mainly gaseous.

4. Meaning of Satellites

Satellites are celestial bodies that revolve around planets. They can be natural satellites, such as the Moon, or artificial satellites, launched by humans for specific purposes.

5. Natural Satellites

Natural satellites revolve around planets due to gravitational force. The Moon is Earth’s natural satellite. Some planets have many natural satellites.

6. Artificial Satellites

Artificial satellites are man-made objects launched into space. They are used for communication, weather forecasting, navigation, and scientific research.

7. Importance of Planets and Satellites

Planets help us understand space and Earth’s position in the universe. Satellites play an important role in modern life by supporting communication, weather prediction, and research.

📝 Questions and Answers

A. Short Answer Questions

(One sentence each)

1. What is a planet?
   Answer: A planet is a celestial body that revolves around the Sun in a fixed orbit.
2. How many planets are there in the Solar System?
   Answer: There are eight planets in the Solar System.
3. What is an orbit?
   Answer: An orbit is the fixed path along which a planet revolves around the Sun.
4. Name any two inner planets.
   Answer: Mercury and Venus are inner planets.
5. Which planet is known as the Red Planet?
   Answer: Mars is known as the Red Planet.
6. What is a satellite?
   Answer: A satellite is a celestial body that revolves around a planet.
7. Name Earth’s natural satellite.
   Answer: The Moon is Earth’s natural satellite.
8. What are artificial satellites?
   Answer: Artificial satellites are man-made objects launched into space.
9. Which planet has the maximum number of satellites?
   Answer: Jupiter has the maximum number of satellites.
10. Why do planets shine in the sky?
    Answer: Planets shine because they reflect sunlight.

B. Long Answer Questions

(3–5 sentences each)

11. Explain what planets are and how they move.
    Answer: Planets are large celestial bodies that revolve around the Sun. They move in fixed paths called orbits. Their motion is controlled by the Sun’s gravitational force. Planets do not have their own light.
12. Describe the inner planets.
    Answer: Inner planets are Mercury, Venus, Earth, and Mars. They are located close to the Sun. These planets are made mainly of rocks and metals. They have solid surfaces.
13. Describe the outer planets.
    Answer: Outer planets include Jupiter, Saturn, Uranus, and Neptune. They are located far from the Sun. These planets are mostly gaseous in nature. They are also called gas giants.
14. What are natural satellites?
    Answer: Natural satellites are celestial bodies that revolve around planets. They are held by gravitational force. The Moon is Earth’s natural satellite. Some planets have many natural satellites.
15. Write a short note on the Moon.
    Answer: The Moon is the natural satellite of Earth. It revolves around the Earth. It reflects sunlight and has no light of its own. The Moon influences tides on Earth.
16. What are artificial satellites and why are they important?
    Answer: Artificial satellites are man-made objects sent into space. They help in communication and weather forecasting. They are used for navigation and scientific research. Satellites play a vital role in modern technology.
17. How are planets and satellites held in space?
    Answer: Planets and satellites are held in space by gravitational force. Gravity keeps planets in their orbits around the Sun. It also keeps satellites moving around planets. This balance maintains the Solar System.
18. Explain the difference between planets and satellites.
    Answer: Planets revolve around the Sun, while satellites revolve around planets. Planets are larger than satellites. Satellites can be natural or artificial. Both move due to gravity.
19. Why is Earth unique among planets?
    Answer: Earth supports life due to the presence of air and water. It has a suitable temperature. Living organisms exist on Earth. This makes Earth special.
20. How do satellites help human life?
    Answer: Satellites help in communication and broadcasting. They assist in weather prediction. Navigation systems depend on satellites. They also help in scientific research.

🧠 Multiple Choice Questions (MCQs)

(With Answers and Detailed Explanations)

1. A planet revolves around the ______.
   a) Moon
   b) Earth
   c) Sun
   d) Star
   Answer: c) Sun
   Explanation: All planets revolve around the Sun.
2. How many planets are there in the Solar System?
   a) Seven
   b) Eight
   c) Nine
   d) Ten
   Answer: b) Eight
   Explanation: There are eight planets in the Solar System.
3. Which of the following is an inner planet?
   a) Jupiter
   b) Saturn
   c) Earth
   d) Neptune
   Answer: c) Earth
   Explanation: Earth is an inner planet.
4. Which planet is the largest?
   a) Earth
   b) Mars
   c) Jupiter
   d) Venus
   Answer: c) Jupiter
   Explanation: Jupiter is the largest planet.
5. What is the fixed path of a planet called?
   a) Axis
   b) Orbit
   c) Circle
   d) Ring
   Answer: b) Orbit
   Explanation: Planets move in fixed paths called orbits.
6. Which planet is known as the Red Planet?
   a) Venus
   b) Mars
   c) Saturn
   d) Uranus
   Answer: b) Mars
   Explanation: Mars looks red due to iron oxide.
7. A satellite revolves around a ______.
   a) Sun
   b) Planet
   c) Star
   d) Asteroid
   Answer: b) Planet
   Explanation: Satellites revolve around planets.
8. Which is Earth’s natural satellite?
   a) Mars
   b) Venus
   c) Moon
   d) Sun
   Answer: c) Moon
   Explanation: The Moon is Earth’s natural satellite.
9. Which planet has the most satellites?
   a) Earth
   b) Mars
   c) Jupiter
   d) Mercury
   Answer: c) Jupiter
   Explanation: Jupiter has many satellites.
10. Artificial satellites are used for ______.
    a) farming
    b) mining
    c) communication
    d) cooking
    Answer: c) communication
    Explanation: Satellites help in communication.
11. Which of these is a gas giant?
    a) Mars
    b) Earth
    c) Jupiter
    d) Mercury
    Answer: c) Jupiter
    Explanation: Jupiter is a gaseous planet.
12. Satellites stay in space due to ______.
    a) wind
    b) gravity
    c) sunlight
    d) heat
    Answer: b) gravity
    Explanation: Gravity keeps satellites in orbit.
13. Which planet has rings?
    a) Mars
    b) Venus
    c) Saturn
    d) Earth
    Answer: c) Saturn
    Explanation: Saturn is famous for its rings.
14. Which planet is closest to the Sun?
    a) Earth
    b) Venus
    c) Mercury
    d) Mars
    Answer: c) Mercury
    Explanation: Mercury is nearest to the Sun.
15. Which satellite affects tides on Earth?
    a) Sun
    b) Mars
    c) Moon
    d) Jupiter
    Answer: c) Moon
    Explanation: The Moon causes tides.
16. Artificial satellites are launched by ______.
    a) nature
    b) planets
    c) humans
    d) stars
    Answer: c) humans
    Explanation: Artificial satellites are man-made.
17. Which planet is farthest from the Sun?
    a) Saturn
    b) Uranus
    c) Neptune
    d) Jupiter
    Answer: c) Neptune
    Explanation: Neptune is the farthest planet.
18. Planets shine because they ______.
    a) produce light
    b) reflect sunlight
    c) burn gases
    d) glow naturally
    Answer: b) reflect sunlight
    Explanation: Planets do not have their own light.
19. The Moon takes about how many days to revolve around Earth?
    a) 7 days
    b) 15 days
    c) 27 days
    d) 30 days
    Answer: c) 27 days
    Explanation: The Moon completes one revolution in about 27 days.
20. Which of the following is not a planet?
    a) Earth
    b) Mars
    c) Moon
    d) Venus
    Answer: c) Moon
    Explanation: The Moon is a satellite, not a planet.

✅ End of Lesson

Prepared strictly in accordance with the NCERT syllabus and CBSE Class 6 examination standards.