INTRODUCTION: If we look at the sky in a dark and clear night, we will notice that the entire sky dotted with countless stars, some bright and some not so bright . We must notice that the moon is the brightest objects in the night sky and the objects which twinkle are stars and the objects which twinkle are stars and the objects which do not twinkle are planets .

                                                                      THE SOLAR SYSTEM

Here some characteristics of solar system will be discussed:

  • The sun and its family of objects which revolve around it is called the solar system.
  • The solar system consists of the sun at its centre and all other objects which revolve around it in a fixed elliptical orbit.
  • There are eight planets of the solar system in order of their increasing distance from the sun which are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
  •  All the planets (except Mercury and Venus) have their natural satellite (or known as moons)around them.
  •  As planets revolve around the sun in the same manner, the natural satellite move around the planets.
  •  The gravitational pull of the Sun keeps all the planets and other objects revolving around it.

                                                                       STARS IN SOLAR SYSTEM

The nearest star from ( nearest star to earth) us is the Sun which is the source of almost all energy on the earth ( nearest star to earth) as it continuously emitting huge amount of heat and light . the Sun is also the main source of heat and light  for all the Planets. .

                                                                          THE PLANET

Here are some information about Planets:

  •  Planets revolve around the Sun in closed elliptical orbits
  •  The Planets do not have light of their own.
  •  The Planets shine and look like stars in the night sky because they reflect the light of the sun which falls on them. 
  •  Planets which are much nearer to us than the stars, they appear to be big and do not twinkle at night. 
  • Every Planet revolves in their separate, fixed path or orbits, they do not collide with one another while revolving around the Sun.
  • The first four Planets Mercury, Venus, Earth, Mars are called inner planets which are made up of rocks and have metallic cores.
  •  These planets have comparatively small and dense bodies consisting of solid surfaces. 
  • Earth is the biggest of the four inner Planets. 
  • The inner Planets have very few natural satellite. 
  •  The Planets outside the orbit of mars, Jupiter, Saturn, Uranus and Neptune are called outer Planets.
  • The outer Planets have a large number of satellites or moons around them. 
  • So, all the Planets revolve around the Sun and also rotate on their axis.
  • The time taken by a Planet to complete one revolution around the Sun is called its period of revolution. 
  •  As the distance of a planet from the Sun increases , its period of revolution also increases. (stars in solar system)
  •  So, the time taken by a planet to complete one rotation on its axis is called its period of rotation. (stars in solar system).

                                                                          ARTIFICIAL SATELLITES

                                           Here are some information about artificial satellite.

  • (stars in solar system) Artificial satellite is a man-made spacecraft placed in orbit around the Earth with the help of a launch vehicle called (stars in solar system)
  • (stars in solar system) Artificial satellites move in an orbit around the Earth at the height of few hundred kilometers. (stars in solar system)
  • (stars in solar system) The motion of artificial satellite into its orbit around the Earth is due to gravitational pull of the Earth. (stars in solar system)
  • (stars in solar system) These satellites carry a large variety of equipments and instruments like cameras, infrared sensors, telescope etc(stars in solar system)

India has built and launched many satellites.   The first artificial satellite launched by india was ARYABHATTA, which was launched in 1975. (stars in solar system)  Some other Indian satellites are BHASKARA, INSAT (Indian national satellite), IRS (Indian Remote Sensing Satellite), ROHINI, KALPANA-1 and EDUSAT (Education Satellite). (stars in solar system)

The agency responsible for the development of space science programmes in our country is INDIAN SPACE RESEARCH ORGANISATION (ISRO) (stars in solar system)



  •  Information is usually collected about other planets, stars, galaxies etc with the help of artificial satellite. (stars in solar system)
  •  These kinds of satellites are used for communication purpose such as long distance transmission of television programmes, telephone calls and internet. (stars in solar system)
  •  These are used for surveying the natural resources of the Earth like minerals, potential fishing zone, agricultural crops etc. (stars in solar system)
  • These are used for weather foreasting such as rainfall, snowfall etc and also for giving advance warning of cyclones and floods. (stars in solar system)


Qs1  Do stars emit light only during night? (the sun solar system)

Ans1  No, stars emit light all the time. But, we can not  observe  the stars during daytime due to the presence of  bright light of sun.  ( the sun solar system)

Qs2  Give the name of the planet which is known to have largest number of natural satellite. (the sun solar system)

Ans2  The planet which is known to have a largest number of satellite is JUPITER (the sun solar system)

QS3  Mention the name of planets that were discovered only after the invention of telescope. (the sun solar system)

Ans3  The planets which were discovered after invention of telescope  are Uranus and Neptune. (the sun solar system)

Qs4  The tail of a comet always point away from the sun, explain why? (the sun solar system)

Ans4 As, the tail of a comet is due to light radiations from the sun , thus it always point away from it.

Qs5  State which planet of the solar system is largest and smallest in size (the sun solar system)

Ans5  The largest planet is Jupiter and the smallest planet is Mercury. (the sun solar system)

Qs6 Give a reason, why the stars are visible only at night? (the sun solar system)

Ans 6 Stars are present both during day time as well as during night time. Because of the bright light of the Sun, the stars are not visible during day time (the sun solar system)., then it is called

Qs7  Mention about the shifting of the sun towards the south and towards the north. (the sun solar system)

Ans7 When sun is shifting towards the south, then it is called dakshnayan and when the sun shifts towards the south, it is called uttarayan. So, the sun shifts towards the south from 21st june  and it starts shifting towards north from 22nd December.

Qs8 As the sun is also a star, then why does it appear so large as compared to the other stars? (the sun solar system)

Ans8  The stars are millions of times farther away than the sun, so, the stars appear to us like points and the sun is like a large sphere. (the sun solar system)

Qs9Explain the reason in brief for not existence of life on the mercury planet . (the sun solar system)

Ans9  As we know that the only planet which is nearest to the sun is Mercury, due to which temperature on it is very high. So, the existence of life on it is impossible. (the sun solar system)Besides this, this planet has no sign of water on its surface and the gases like carbon dioxide, hydrogen, oxygen and nitrogen do not exist in its atmosphere. (the sun solar system)

Qs10  The stars appear to move from east to west , explain  why with the help of a reason. (the sun solar system)

Ans10  As we know that the earth rotates from west to east direction due to which the stars appear to move from east to west direction as seen from the earth(the sun solar system)























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