The Earth in the Solar System with notes (हिंदी में) || Class 6 Chapter 1 Geography ||


Chapter 1, Class 6
THE EARTH IN THE SOLAR SYSTEM
1.       The whole sky is filled with tiny (बहुत छोटा) shining objects – some are bright (चमकदार), others dim and cannot count.
2.       They all appear to be twinkling (टिमटिमाहट).
3.       But if you look at them carefully you will notice that some of them do not twinkle as others do.
4.       They simply glow without any twinkling just as the moon shines.  
5.       Along with these bright objects, you may also see the moon on most of the days.
6.       It may appear at different times, in different shapes and at different positions.
7.       You can see the full moon only once in a month and called Full moon night or Poornima.
8.       A fortnight (दो सप्ताह) later, you cannot see it at all & it is a New moon night or Amavasya.
9.       On this day, you can watch the night sky best, provided it is a clear night.
10.   We can’t see the moon & small objects during day time due to the brightness of the sun.
11.   The sun, the moon and all those objects shining in the night sky are called celestial (खगोलीय) bodies.
12.   Some celestial bodies are very big and hot.
13.   They are made up of gases.
14.   They have their own heat and light, which they emit in large amounts.
15.   These celestial bodies are called stars like sun.
16.   Countless (अनगणित) twinkling stars in the night sky are similar to the sun.
17.   But we do not feel their heat or light, and they look so small because they are very very far from us.
18.   While watching the night sky, you may notice various (अनेक) patterns formed by different groups of stars.
19.   These are called constellations (नक्षत्रमंडल).
20.   Ursa Major or Big Bear is one such constellation.
21.   One of the most easily findable constellations is the Saptarishi (Saptaseven, rishi-sages).
22.   It is a group of seven stars that forms a part of Ursa Major Constellation.
23.   In ancient (प्राचीन) times, people used to determine directions during the night with the help of stars.
24.   The North Star indicates the north direction & also called Pole Star.
25.   It always remains in the same position in the sky.
26.   Some celestial bodies do not have their own heat and light.
27.   They shine by the light of the stars.
28.   Such bodies are called planets.
29.   The word ‘planet’ comes from the Greek word “Planetai” which means ‘wanderers (घुमक्कड़)’.
30.   The earth is a planet & gets all its heat and light from the sun.
31.   If we look at the earth from a great distance, like moon, it will appear to be shining just as the moon.
32.   The moon that we see in the sky is a satellite (उपग्रह) & moves round the earth.
33.   Like our earth, there are seven other planets that get heat and light from the sun.

THE SOLAR SYSTEM
1.       The sun, eight planets, satellites and some other celestial bodies known as asteroids and meteoroids form the solar system.
2.       We often call it a solar family, with the sun as its Head.

The Sun
1.       The sun is in the centre of the solar system.
2.       It is huge (बहुत बड़ा) and made up of extremely hot gases like Hydrogen -71%, Helium -26.5% & others 2.5%
3.       It provides the pulling force that binds the solar system.
4.       But that tremendous (भयंकर) heat is not felt so much by us because it is far away from us.
5.       The sun is about 150 million (15 crore) km away from the earth.
6.       Diameter of the sun is 13, 92,000 Km.
7.       Light reaches the earth in 8 Min. & 16.6 sec
8.       Surface temperature of the Sun is 6000 °C.

Planets
1.       There are 8 planets in our solar system.
2.       In order of their distance from the sun, they are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
3.       All the 8 planets of the solar system move around the sun in fixed paths.
4.       These fixed paths are called orbits.
5.       Mercury is nearest to the sun.
6.       It takes only about 88 days to complete one round along its orbit.
7.       Venus is considered as ‘Earth’s-twin’ because its size and shape are very much similar to the earth.
8.       Till recently (August 2006), Pluto was also considered a planet.
9.       However, in a meeting of the International Astronomical Union, a decision was taken that Pluto like other celestial objects (Ceres) called as ‘dwarf planets.”
The Earth
1.       The earth is the 3rd nearest planet to the sun.
2.       In size, it is the 5th largest planet.
3.       It is slightly flattened (चपटा होना) at the poles.                                
4.       That is why; its shape is described as a Geoid.
5.       Geoid means an earth-like shape.
6.       Conditions favourable to support life are found only on the earth.
7.       The earth is neither too hot nor too cold.
8.       It has water and air, which are very important for our survival (जीवित रहना).
9.       The air has gases like oxygen.
10.   Because of these reasons, the earth is a unique planet in the solar system.
11.   From the outer space, the earth appears (प्रतीत होना) blue because its two-thirds surface is covered by water.
12.   It is, therefore, called a blue planet or watery planet.

The Moon
1.       Our earth has only one satellite, that is, the moon.
2.       Its diameter is only 1/4th of the earth.
3.       It appears (प्रतीत होना) so big because it is nearer to our planet than other celestial bodies.
4.       It is about 3, 84,400 km away from us.
5.       The moon moves around the earth in 27 days 8hours.
6.       It takes exactly the same time to complete one spin.
7.       As a result, only one side of the moon is visible (प्रकट) to us on the earth.
8.       It does not support for life.
9.       It has mountains, plains and depressions on its surface.
10.   Time taken by Moonlight to reach earth – 1.3 sec

Asteroids
1.       Apart (छोड़कर) from the stars, planets and satellites, there are numerous (बहुत ज्यादा) tiny (बहुत छोटा) bodies which also move around the sun.
2.       These bodies are called asteroids.
3.       They are found (पाया जाना) between the orbits of Mars and Jupiter.
4.       Scientists believe that asteroids are parts of a planet which exploded (विस्फोट) many years back.

Meteoroids
1.       The small pieces of rocks which move around the sun are called meteoroids (उल्का).
2.       Sometimes these meteoroids come near the earth and looks like to drop (गिरना) upon it.
3.       During this process due to friction (रगड़) with the air they get heated up and burn.
4.       It causes a flash (चमक) of light.
5.       Sometimes, a meteor without being completely burnt falls on the earth and creates a hollow.
6.       It is a cluster (झुंड) of millions of stars.
7.       Our solar system is a part of Milky Way galaxy.
8.       In ancient India, it was imagined to be a river of light flowing in the sky.
9.       Thus, it was named Akash Ganga.
10.   A galaxy is a huge system of billions of stars, and clouds of dust and gases.
11.   There are millions of such galaxies that make the Universe.






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