Class 8
Chapter 17 Class 8 - Stars and the Solar System

Different planets of Solar System are

Different Planets of Solar System - Teachoo.jpg

 

Name of Planet Description Number of Moons

Mercury
(Budh)

It is nearest planet to sun

0

It is the smallest planet of solar system
It is visible just near horizon during sunrise or sunset

Venus
(Shukra)

It is nearest to earth

0

It is brightest in sky
Sometimes Venus appears in the eastern sky before sunrise. Sometimes it appears in the western sky just after
sunset.
So, it is called morning star or evening star

Earth
(Prithvi)

It is neither too close too sun nor too far(so it is neither too hot nor too cold)

1

It has its own atmosphere and presence of water

Mars
(Mangal)

It is slightly reddish in color so it is called red planet

2

Jupiter
(Brihaspati)

It is largest planet

79(4 visible by small telescope

Size of Jupiter is 1300 times of that of earth
Mass is 318 time that of earth
It has faint rings around it

Saturn
(Shani)

It is yellow in color

Many (62)

It has number of rings around it which cannot be visible with the naked eyes but can be seen with a telescope
It also has large number of satellites.
It is the least dense planet(density is less than water)

Uranus
(Arun Grah)

It rotates from east to west

Many (27)

It has a highly tilted rotation axis,it appears to roll on its side.
Uranus can be seen with the help of a large telescope

Neptune
(Drivya Man)

It is the outermost planet

Many (14)

Neptune can be seen only with help of large telescope

 

Solar System - Teachoo.jpg

 

Note: The planets do not have light of their own. They reflect the light of the Sun that falls on them.

Name the inner planets of the solar system

Planets which are close to the sun are known as the inner planet

They are Mercury,Venus,Earth,Mars

Inner planets have very few moons

 

Name the outer planets of the solar system

Planets which are far away from sun are known as the outer planets

They are Jupiter,Saturn,Uranus,Neptune

Outer planets have large number of moons

 

How does Earth appears from Moon

Earth appears to be of blue-green color because of the reflection of water and land on its surface

 

What causes change of season on Earth

It is due to rotational axis of earth which is tilted

Part of earth which is nearer to sun has summers

Part of earth which is far from sun have winters

Example

In Northern Hemisphere(India,England) we have summers in May-june and winters in Dec-Jan

In Southern Hemisphere (Australia,New Zealand) there are winters in may-June and summers in Dec -Jan

Different Seasons on Earth - Teachoo.jpg

 

Difference between Rotation and Revolution

Rotation and Revolution - Teachoo.png

 

Rotation

Movement of planet around its axis is called Rotation

Example

Earth takes one day to rotate around sun

 

Revolution

Movement of one object around another object is called revolution

Example

Earth takes One Year to Complete One Revolution around the sun

Rotation and Revolution GIF

 

What is Period of Rotation and Period of Revolution

Period of Rotation Period of Revolution
Time taken by a planet to complete one rotation is known as the period of Rotation Time taken by a planet to complete one revolution is known as a period of Revolution
Earth takes 24 hours to spin once around its axis. Its period of rotation is 24 hours or a day.
Earth takes 365 days to complete one revolution around the sun. The period of revolution of earth around the sun is 365 days.

 

What is an Orbit?

Path which a planet takes to revolve around sun is called orbit

Example

Earth has a definite path,it always take same path while revolving around sun

This path is called orbit

What is an orbit.jpeg

Questions

NCERT Question 2 -  Which of the following is NOT a planet of the sun?

(a) Sirius

(b) Mercury

(c) Saturn

(d) Earth

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NCERT Question 4 (a) -  The planet which is farthest from the Sun is ____________ . .

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NCERT Question 4 (b) -  The planet which appears reddish in colour is ____________ .

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NCERT Question 5 (b) - Mark the following statements as true (T) or false (F):

Mercury is the smallest planet of the solar system. ( )

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NCERT Question 5 (c) -  Mark the following statements as true (T) or false (F):

Uranus is the farthest planet in the solar system. ( )

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NCERT Question 5 (e) -  Mark the following statements as true (T) or false (F):

There are nine planets in the solar system. ( )

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NCERT Question 6 (i) -  Match items in column A with one or more items in column B: A B

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NCERT Question 7 - In which part of the sky can you find Venus if it is visible as an evening star?

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NCERT Question 8 - Name the largest planet of the solar system.

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CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo