The Earth in the Solar System – Complete Notes

The Earth in the Solar System – Complete Notes + Previous Year Questions

Introduction

The universe is a vast expanse filled with countless stars, planets, satellites, and galaxies. Our planet Earth is just a small part of this magnificent system known as the Solar System. Understanding celestial bodies, their movement, and the structure of our solar family helps us know where we belong in this vast universe.

What Are Celestial Bodies?

The Sun, the Moon, and all the objects that shine in the night sky are called celestial bodies.
Some are very large and hot, made of gases, and emit their own heat and light — these are called Stars.
Others like planets and satellites do not produce their own light but reflect light from the stars.

Stars, Planets, and Satellites

Constellations and the Pole Star

A constellation is a group of stars forming a pattern.
The Saptarishi (Ursa Major or Big Bear) is one of the most easily recognizable constellations in the night sky.
The Pole Star (Dhruva Tara) always indicates the north direction, which makes it an important celestial reference point.

Planets in Our Solar System

There are eight planets in the Solar System.
In order of their distance from the Sun, they are:

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

Other Celestial Bodies

• Asteroids – Small rocky bodies found between Mars and Jupiter.
• Meteoroids – Tiny rocky fragments that move around the Sun.
• Comets – Bodies made of dust and ice that develop a glowing tail when near the Sun.
• Galaxy – A vast system of stars, dust, and gases. Our galaxy is the Milky Way.

The Sun – Our Nearest Star

The Sun is about 150 million kilometers away from Earth.
It provides the energy that sustains life and controls climate and weather patterns.

Light from the Sun takes about 8 minutes to reach Earth!

The Earth – Our Unique Home

Earth is the third planet from the Sun and the only known planet that supports life.
It is slightly flattened at the poles — giving it a geoid shape (Earth-like).
About two-thirds of Earth’s surface is covered by water.

 The Moon – Earth’s Natural Satellite

• Distance from Earth: 3,84,400 km
• Takes 27 days to complete one orbit around Earth
• Always shows only one side to Earth
• Appears bright because it reflects sunlight

Structure of the Solar System

Inner vs Outer Planets

Key Facts Summary

• The Sun is a star.
• Planets reflect sunlight, they don’t have their own light.
• Earth is slightly flattened at the poles — hence called Geoid.
• Venus is called Earth’s Twin.
• Jupiter is the largest planet.
• Saturn, Jupiter, Uranus have visible rings.
• Asteroids are found between Mars and Jupiter.

1. The sun, the moon and all those objects shining in the night sky are called ______.
This question was previously asked in
SSC CGL (2020) Paper – 3 March Shift 2
1. Stars
2. Satellites
3. Celestial bodies
4. Milky Way
Answer (Detailed Solution Below)
Option 3: Celestial bodies

2. Objects that shine in the night sky are known as:
CTET Paper 1 (2019)
1. Meteoroids
2. Constellations
3. Asteroids
4. Celestial bodies
Answer (Detailed Solution Below)
Option 4: Celestial bodies

3. Bodies that do not have their own heat and light but are lit by the light of the stars are called:
CTET Nov 2012 Paper – 2 Social Studies
1. Stars
2. Constellations
3. Planets
4. Celestial bodies
Answer (Detailed Solution Below)
Option 3: Planets

4. The pole star indicates the direction of the:
DSSSB PRT Official Paper – 30 Sept 2018
1. North
2. South
3. East
4. West
Answer (Detailed Solution Below)
Option 1: North

5. Which of the following planets has a ring around it?
Tripura TET 2019 (Paper II)
1. Jupiter
2. Uranus
3. Both Jupiter and Uranus
4. None of the above
Answer (Detailed Solution Below)
Option 3: Both Jupiter and Uranus

6. The sun is about ____ km away from the Earth.
SSC GD Constable (2023)
1. 20 million
2. 150 million
3. 50 million
4. 100 million
Answer (Detailed Solution Below)
Option 2: 150 million

7. All the planets in the solar system move around the sun in a/an:
DSSSB PRT Official Paper – 2018
1. Circular path
2. Elongated path
3. Rectangular path
4. Triangular path
Answer (Detailed Solution Below)
Option 2: Elongated path

8. The planet Mercury takes about ____ Earth days to complete one orbit around the Sun.
UPPCL JE CE 2022
1. 365
2. 255
3. 88
4. 687
Answer (Detailed Solution Below)
Option 3: 88

9. Which planet in the solar system is considered Earth’s twin?
SSC MTS 2022 (Shift 2)
1. Mercury
2. Saturn
3. Neptune
4. Venus
Answer (Detailed Solution Below)
Option 4: Venus

10. Why is the Earth described as a ‘Geoid’?
CTET 2015 Paper II
1. Earth is slightly flattened at the poles.
2. Earth is neither too hot nor too cold.
3. Two-thirds of the Earth’s surface is covered with water.
4. Favourable conditions exist for life.
Answer (Detailed Solution Below)
Option 1: Earth is slightly flattened at the poles.

11. Which is the natural satellite of Earth?
RRB JE CE (2019)
1. Moon
2. Aryabhatta
3. Kalpana-1
4. INSAT
Answer (Detailed Solution Below)
Option 1: Moon

12. The Moon moves around the Earth in about how many days?
SSC MTS 2023
1. 21
2. 23
3. 27
4. 25
Answer (Detailed Solution Below)
Option 3: 27

13. Tiny bodies that move around the Sun and are found between Mars and Jupiter are called:
CTET 2022 Paper II
1. Satellites
2. Meteoroids
3. Comets
4. Asteroids
Answer (Detailed Solution Below)
Option 4: Asteroids

14. A group of stars forming a particular pattern or shape in the night sky is known as:
SSC GD Constable (2021)
1. Galaxy
2. Asteroid
3. Constellation
4. Meteor
Answer (Detailed Solution Below)
Option 3: Constellation

15. Which of the following is the largest planet in our solar system?
SSC CGL 2022
1. Earth
2. Mars
3. Jupiter
4. Saturn
Answer (Detailed Solution Below)
Option 3: Jupiter

16. Which planet is known as the ‘Red Planet’?
CTET 2021
1. Mercury
2. Mars
3. Venus
4. Jupiter
Answer (Detailed Solution Below)
Option 2: Mars

17. Which planet is closest to the Sun?
SSC CHSL 2022
1. Earth
2. Venus
3. Mercury
4. Mars
Answer (Detailed Solution Below)
Option 3: Mercury

18. The planet known for its beautiful rings is:
CTET 2019 Paper II
1. Uranus
2. Saturn
3. Jupiter
4. Neptune
Answer (Detailed Solution Below)
Option 2: Saturn

19. The Milky Way galaxy is also called:
DSSSB 2020 Paper
1. Andromeda
2. Akash Ganga
3. Orion
4. Ursa Major
Answer (Detailed Solution Below)
Option 2: Akash Ganga

20. Which planet is farthest from the Sun?
CTET 2020 Paper II
1. Neptune
2. Uranus
3. Jupiter
4. Saturn
Answer (Detailed Solution Below)
Option 1: Neptune

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