24 September 2014

The Earth in the Solar System

The Celestial Bodies : Cbse / Ncert Class 6 Revision Notes

A night when one side of the moon is completely visible from the earth is called a Full Moon night or PoornimaA night without a moon or a no moon night is called a New Moon night. In Hindi, a New moon night is called Amavasya.

The night sky is full of innumerable twinkling bodies. These bodies are called stars. They are very big and hot celestial bodies made up of gases and emit large amounts of heat and light. Stars closer to earth appear brighter. The sun is the star closest to us.

Clusters of billions of stars along with dust and gas are bound together by gravity. Such clusters of stars are called galaxies. Millions of galaxies together make up our Universe. Some stars in ancient times did not twinkle and just glowed steadily. These celestial bodies were called the “wandering stars”. Today, we recognise these bodies as planets.

Must Read: Solar System

A planet moves around a star along a fixed path and does not have its own heat and light but receives heat and light from the star around which it moves. There are seven other planets that move around the sun in fixed paths. Some planets have other celestial bodies moving around them. These celestial bodies are called satellites. The moon moves around the earth; it is the earth’s satellite.

It was observed that different groups of stars formed unique and beautiful patterns. These patterns were given a common name, constellations. There are, in all, 88 constellations known to man. Ursa Major or the Big Bear is one of the most well-known and easily recognisable constellations. Within a constellation, small star patterns can also be observed. These stars patterns are called asterisms. One such asterism is formed by the seven brightest stars of the Ursa Major. This asterism is called the Small Bear or the Saptarishi in Hindi. The two stars that form the edge of the bear’s bowl are called the Pointer Stars.

The pointer stars point to the Polaris or the Pole Star. The Polaris seems to remain aligned to the earth’s North Pole. This is the reason why the Polaris is also called the North Star. In Hindi, the Polaris is called the Dhruva Tara. The sun’s light is very bright. Hence, the other celestial bodies pale off and are barely visible to the naked eye. The planet Venus is another celestial body that can be seen during the day. Venus is also called the Morning Star.

CBSE NCERT Class VI (6th) | Social Studies | Geogrphy

Chapter  :  The Earth in the Solar System

CBSE NCERT Solved Question Answer

Q1. Answer the following questions briefly:

a) How does a planet differ from star?
i) Stars emit their own heat and light while planets do not have their own light.
ii) There are millions of stars while we have only eight planets in the solar system.

b) What is meant by the ‘solar system’?
Answer The sun, eight planets, satellites and some other celestial bodies known as asteroids and meteoroids form the solar system. The sun is in the centre of the solar system. All the planets of the solar system move around the sun in fixed paths.

c) Name all the planets according to their distance from the sun.
Answer Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

d) Why Earth is called a unique planet?
Answer Earth is called a unique planet because of the following reasons:
1. The land, air, water, favorable climatic facilities and the origin of life is possible on earth.
2. The earth is neither too hot nor too cold.
3. The earth has life supporting gases like oxygen.
4. No other planet of the solar system has life like that of earth.

e) Why do we see only one side of the moon always?
Answer The moon moves around the earth in about 27 days. It takes exactly the same time to complete one spin. As a result only one side of the moon is visible to us on the earth.

f) Define universe?
Answer Universe is a cluster of galaxies. It is vast and ever expanding.

Q2. Fill in the blanks:
1. The planet known as the ‘earth’s twin’ is Venus.
2. Third nearest planet to sun is Earth.
3. The pole star indicates the direction to the North.
4. Asteroids are found between the orbits of Mars and Jupiter.
5. A group of stars forming various patterns is called as constellation.
6. A huge system of stars is called as galaxy.
7. The moon is the closest celestial body to our earth.
8. Planets do not have their own heat and light.
9. The stars are not visible during the day because of sun’s brightness.
10. The moon is a natural satellite.

Q3. Name the nearest star to the earth.
Answer The nearest star to the earth is the Sun.

Q4. Name the second nearest star to the earth after sun.
Answer Proxima Centuari is the second nearest star to the earth.

Q5. Why earth is called a ‘blue planet’?
Answer Earth is called a blue planet because two third of earth’s surface is covered with water.

Q6. How much time does it take for the light of the sun to reach earth?
Answer It takes about 8 minutes for the light of the sun to reach earth.

Q7. Name the first person who stepped on the surface of the moon?
Answer Neil Armstrong was the first person who stepped on the surface of the moon