The Earth and The Solar System PDF

# The Earth : An Introduction ## The Earth and The Solar System **Let's Start** She was an Indian-born American astronaut and mechanical engineer. She was also the first woman of Indian origin to go to space. What is her name? **Kalpana Chawla** The family of the Sun, eight planets and their sa...

# The Earth : An Introduction ## The Earth and The Solar System **Let's Start** She was an Indian-born American astronaut and mechanical engineer. She was also the first woman of Indian origin to go to space. What is her name? **Kalpana Chawla** The family of the Sun, eight planets and their satellites make up the solar system. ## The Sun The Sun is the center of the solar system. All planets and satellites revolve around it. It is the source of all energy in the solar system. Life on Earth is possible only because of sunlight. Without the Sun's heat and energy, our Earth would become a cold and lifeless planet. The light from the Sun, takes about eight minutes to reach the earth. ## Planets Our solar system consists of eight planets. According to their distance from the Sun, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. **Do and Learn** Unscramble the names of the following planets and write in the spaces provided. - CRYUEMR - **Mercury** - SVNEU - **Venus** - RAMS - **Mars** The largest planet is **Jupiter** and the smallest planet is **Mercury**. **Mercury** is nearest to the Sun whereas **Neptune** is the farthest. **Saturn** has a ring around it. **Venus** is closest to the Earth. **Star Fact** Originally our solar system included nine planets. In 2006, the International Astronomical Union (IAU) declared **Pluto** as a dwarf planet. ## Satellites There are two types of satellites - Natural satellites and artificial satellites. Satellites are smaller friends of planets. They revolve around planets in fixed orbits. Satellites do not have their own heat and light. They reflect the light of the Sun. There are over 100 satellites in our solar system. **Moon** is the only satellite of the Earth. Artificial satellites are sent into space by scientists to study weather phenomena and for the purpose of telecommunication. ## Revolution of the Earth - The movement of planets around the Sun on a fixed orbit is called **revolution** - The movement of planets around their own axis is called **rotation** - An object in space that revolves around a planet is called a **satellite** ## Stars Stars are self-luminous bodies. It means they have their own heat and light. Stars are made of hot, burning gases. They are usually very big in size but as they are very far away from us they look small and tiny like little dots in the sky. Our Sun is also a star. It looks bigger and brighter because, compared to other stars, it is much nearer to Earth. **Discuss:** Why is the Earth called a unique planet? **Let Us Recall** - The family of the Sun, planets and satellites comprise the solar system. - There are eight planets - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. - Mercury is nearest to the Sun whereas Neptune is the farthest. - Movement of planets around the Sun is called **Revolution**. - Movement of planets on their own axis is called **Rotation**. ## Think and Answer **A. Tick (✔) the right answer.** 1. The light from the Sun takes about ___ minutes to reach the Earth. - (a) Five - (b) Six - (✔) Eight 2. Which is the largest planet? - (a) Mercury - (✔) Jupiter - (c) Saturn 3. Which is the smallest planet? - (✔) Mercury - (b) Saturn - (c) Earth