Class 6 Geography Chapter 1: The Earth in the Solar System (सौरमंडल में पृथ्वी)
A foundational, beautifully illustrated masterclass introducing our planetary neighborhood, the cosmos, and the unique place of planet Earth.
1. Celestial Bodies (खगोलीय पिंड)
The Sun, the Moon, and all those objects shining in the night sky are called Celestial Bodies (खगोलीय पिंड).
- Stars (तारे): Some celestial bodies are very big and hot. They are made up of gases and possess their own heat and light, which they emit in large amounts. The Sun is a star.
- Constellations (नक्षत्रमंडल): Various patterns formed by different groups of stars are called constellations.
- Ursa Major (Big Bear) is one of the most recognizable constellations.
- Saptarishi (Seven Sages): A group of seven stars that forms a part of Ursa Major.
- The Pole Star (ध्रुव तारा): Indicates the North direction. It always remains in the same position in the sky and was used by ancient travellers for navigation.
2. The Solar System (हमारा सौरमंडल)
The Sun, eight planets, satellites, and some other celestial bodies known as asteroids and meteoroids form the Solar System. We often call it a solar family, with the Sun as its Head.
The Sun (सूर्य):
- The center of the solar system, made up of extremely hot gases.
- Provides the pulling gravitational force that binds the entire solar system.
- The ultimate source of heat and light for the solar system, located about 150 million km away from Earth.
The Eight Planets (आठ ग्रह):
In order of their distance from the Sun:
- Mercury (बुध): Nearest to the Sun; takes only 88 days for one orbit.
- Venus (शुक्र): Earth’s “twin” because its size and shape are very similar to Earth.
- Earth (पृथ्वी): Our home planet; 3rd nearest to the Sun and 5th largest planet.
- Mars (मंगल): The red planet.
- Jupiter (बृहस्पति): Largest planet in the solar system.
- Saturn (शनि): Famous for its spectacular ring system.
- Uranus (यूरेनस).
- Neptune (नेप्च्यून): Farthest planet from the Sun.
Mnemonic to remember planetary order:
My Very Efficient Mother Just Served Us Nuts.
3. Earth: The Unique Planet (अनोखा ग्रह)
The Earth is the only known planet that supports life because:
- Moderate Temperature: It is neither too hot nor too cold.
- Water and Air: It has liquid water and life-supporting gases, particularly oxygen.
- The Blue Planet: From outer space, the Earth appears blue because two-thirds of its surface is covered by water.
4. The Moon (हमारा उपग्रह: चंद्रमा)
- Earth has only one natural satellite: The Moon.
- Its diameter is only one-quarter that of Earth.
- Distance from Earth: about 3,84,400 km.
- The Moon moves around the Earth in about 27 days and takes exactly the same time to complete one spin on its axis. As a result, only one side of the moon is visible to us on Earth.
- Neil Armstrong was the first person to step on the surface of the moon on 20 July 1969.
5. Asteroids and Meteoroids (क्षुद्रग्रह एवं उल्कापिंड)
- Asteroids (क्षुद्रग्रह): Numerous tiny bodies that move around the Sun. Found between the orbits of Mars and Jupiter (Asteroid Belt). Scientists believe they are parts of a planet that exploded long ago.
- Meteoroids (उल्कापिंड): Small pieces of rocks which move around the Sun. Sometimes they come near the Earth and drop upon it, creating friction with the air and causing a flash of light (“shooting stars”).
- Galaxy & Universe: A Galaxy (like our Milky Way / Akash Ganga) is a huge system of billions of stars, dust clouds, and gases. Millions of such galaxies together make up the Universe.
Compiled by NCERT Classes Academic Team, Jodhpur. 100% Free Public Commons.
