NCERT Solutions For Class 6 Geography Chapter 1: The Earth In The Solar System
Chapter Overview
This chapter introduces students to our solar system and Earth's place within it. It covers the celestial bodies that make up our solar neighborhood, including the sun, planets, and other objects like asteroids, comets, and meteoroids. Understanding our cosmic address and Earth's unique characteristics as the only known planet to support life is fundamental to geographical knowledge.
Key Concepts to Remember
- Solar System: The system comprising the Sun and the celestial bodies held by its gravitational force.
- Planet: A large celestial body that revolves around the Sun in a fixed orbit.
- Celestial Bodies: All natural objects visible in the sky, such as the Sun, Moon, stars, etc.
- Satellite: A celestial body that orbits around a planet.
- Asteroid Belt: The region between Mars and Jupiter where most asteroids orbit the Sun.
NCERT Solutions
Question 1: Answer the following questions briefly.
(a) How does a planet differ from a star?
Answer: A planet differs from a star in several ways:
- Planets do not have their own light but reflect the light of the Sun, while stars have their own light.
- Stars are much larger in size compared to planets.
- Planets revolve around stars (like the Earth around the Sun), while stars remain relatively fixed in their position in the constellation.
- Stars produce energy through nuclear fusion, while planets do not.
(b) What is meant by the 'solar system'?
Answer: The solar system is the family of the Sun, eight planets, their satellites, asteroids, meteoroids, comets, and other celestial bodies that revolve around the Sun due to its gravitational force. The Sun is at the center of this system, and all other bodies are held together by its gravitational pull.
(c) Name all the planets of the solar system as per their distance from the sun.
Answer: The planets of our solar system arranged according to their distance from the Sun are:
- Mercury
- Venus
- Earth
- Mars
- Jupiter
- Saturn
- Uranus
- Neptune
(d) Why is the Earth called a "unique planet"?
Answer: Earth is called a "unique planet" because:
- It is the only planet in the solar system that supports life as we know it.
- It has an atmosphere containing the gases essential for life, such as oxygen, nitrogen, and carbon dioxide.
- It has water in all three states - liquid, solid (ice), and gas (water vapor).
- It is neither too hot nor too cold, providing conditions suitable for life.
- It has a natural satellite, the Moon, which influences tides and other phenomena on Earth.
(e) Why do we see only one side of the moon always?
Answer: We see only one side of the Moon always because:
- The Moon takes approximately 27.3 days to complete one rotation on its axis.
- The Moon also takes the same amount of time (27.3 days) to complete one revolution around the Earth.
- This synchronous rotation means that the Moon always shows the same face to the Earth.
(f) What is the Universe?
Answer: The Universe is the vast expanse of space that contains everything that exists - all galaxies, stars, planets, satellites, matter, energy, and even empty space. It is endlessly expanding and contains billions of galaxies, each with billions of stars. Our solar system is a tiny part of the Milky Way galaxy, which is just one of billions of galaxies in the Universe.
Question 2: Tick the correct answer.
(a) The planet known as the "Earth's Twin" is
Answer: (i) Venus
(b) Which is the third nearest planet to the sun?
Answer: (iii) Earth
(c) All the planets move around the sun in a
Answer: (i) Circular path
(d) The Pole Star indicates the direction to the
Answer: (ii) North
(e) Asteroids are found between the orbits of
Answer: (ii) Mars and Jupiter
Question 3: Fill in the blanks.
(a) A group of ________ forming various patterns is called a ________.
Answer: stars, constellation
(b) A huge system of stars is called ________.
Answer: galaxy
(c) ________ is the closest celestial body to our earth.
Answer: Moon
(d) ________ is the third nearest planet to the sun.
Answer: Earth
(e) Planets do not have their own ________ and ________.
Answer: light, heat
Additional Information about the Solar System
Planetary Classification
Planets in our solar system can be categorized in two ways:
- Inner (Terrestrial) Planets: Mercury, Venus, Earth, Mars - These are smaller, denser, and composed mainly of rock and metal.
- Outer (Jovian) Planets: Jupiter, Saturn, Uranus, Neptune - These are larger, less dense, and composed mainly of gases and ice.
The Dwarf Planets
Since 2006, Pluto has been classified as a dwarf planet. Other dwarf planets include Ceres, Eris, Haumea, and Makemake. These are smaller celestial bodies that orbit the Sun but have not cleared their orbital paths.
Earth's Special Characteristics
Earth's special features that make it conducive to life include:
- The right distance from the Sun (in the "habitable zone")
- A suitable atmosphere for respiration and protection
- Abundant water in liquid form
- A magnetic field that shields from harmful solar radiation
- A suitable temperature range
Interesting Facts about Our Solar System
- Jupiter is the largest planet and Mercury is the smallest.
- Venus is the hottest planet due to its dense atmosphere.
- Saturn has the most beautiful rings made of ice and rock particles.
- The Great Red Spot on Jupiter is a giant storm larger than Earth.
- One day on Venus is longer than its year.
Understanding Celestial Bodies
Stars
Stars are massive, luminous spheres of hot gas, mostly hydrogen and helium. They produce energy through nuclear fusion in their cores. Our Sun is a medium-sized star and the closest star to Earth. Other stars appear much smaller due to their enormous distances from us. Stars are grouped together to form galaxies, and when they form recognizable patterns, these patterns are called constellations.
Comets
Comets are celestial objects consisting of a nucleus of ice and dust. When a comet approaches the Sun, the heat vaporizes the ice, creating a glowing atmosphere called a coma, and often a visible tail that always points away from the Sun. Notable comets include Halley's Comet, which appears every 76 years.
Meteoroids
Meteoroids are small rocky or metallic bodies that range in size from a grain of sand to large boulders. When meteoroids enter Earth's atmosphere at high speeds, they burn up due to friction, creating bright streaks of light known as meteors or "shooting stars." If they survive this passage and land on Earth, they are called meteorites.
The Sun
The Sun contains 99.8% of the total mass of our solar system. It is about 4.6 billion years old and is expected to continue shining for another 5 billion years. The energy from the Sun drives Earth's climate and weather and makes life possible on our planet.
Study Tips for This Chapter
- Create a visual diagram of the solar system with planets in correct order.
- Use mnemonic devices to remember the order of planets (e.g., "My Very Educated Mother Just Served Us Noodles").
- Compare features of different planets in a tabular format for easy revision.
- Understand the reasons for Earth's ability to support life compared to other planets.
- Relate the concepts to current news about space exploration.
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