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Class 10 Class 12

What is solar system? Name the planets situated between the sun and the earth.


The Solar system consists of the Sun and the celestial bodies which revolve around the Sun. Added to that it consists of a large number of bodies such as planets, comets, asteroids and meteors. The sun is the centre of the solar system and all the planets revolve around the sun in elliptical paths called orbits. 

The planets situated between the sun and the earth are Mercury and Venus.


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Why life is not possible on the planet Mercury?


Planet Mercury being closest to the Sun has extremely high temperature on it making the survival of life impossible. Moreover, Mercury does not have water on its surface and there is no carbon dioxide, hydrogen, nitrogen and oxygen in its atmosphere. Also, there is no protective blanket around the Mercury planet to prevent harmful radiations from reaching its surface. 

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Name two planets which appear as ‘morning star and evening star’ and why?


Mercury and Venus are the two planets that can be seen as morning and evening star in the sky.

Mercury being the closest to the Sun is hidden in the glare of the sun and is rarely visible. However, it can be observed just before the sunrise or after the sunset near the horizon.

Venus appears in the eastern sky before sunrise and appears in the western sky after the sunset. 

Due to their visibilty before sunrise and after sunset, they are called evening and morning star. Also, Mercury and Venus lie inside the orbit of the earth.

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What happens to meteors when they enter the earth’s atmosphere?


When meteors enters the earth's atmosphere, its speed is very high. The friction due to the Earth's atmosphere heats it up. On heating up, it emits light and glows producing a bright streak of light. Since they get evaporated quickly, the bright streaks lasts only for a short duration of time.

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How is the pole star located in the sky? Why is it so special?



The earth rotates on its axis from west to east, therefore, the stars appear to move in opposite direction, i.e. east to west. But pole star lies on the axis of rotation of earth, which is fixed. Hence, pole star appears to be fixed in the sky.

Pole star lies in the northern part of the sky and enables us to find the North direction.


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Explain the importance of stars for the people in ancient times.


The ancient people found the night sky to be very useful to find the direction. The position of pole star remained fixed in the north sky and it indicated North direction. As the stars change their position with time, it has been possible to find the time with relative position of stars. 

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