NCERT Class 6 Geography Chapter 1: Earth in Solar System Complete Notes Part 3 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Earth in Solar System

Dwarf Planets

  • Ceres - largest object in asteroid between Mars and Jupiter
  • Pluto – Small Size, Offbeat Orbit, Beyond Kuiper Belt, Now Planetoid
  • Eris - 2003 UB313 – 10th planet & largest dwarf discovered
  • Oort Cloud are composed of ices like ammonia, methane & water
  • Kuiper Belt – Ice belt beyond Neptune
  • Planet Nine in Kuiper Belt is 10 times the mass of Earth and 5,000 times the mass of Pluto.
  • Kuiper similar to asteroid belt between Mars and Jupiter

Kuiper belt that exist beyond Neptune. This is a belt of ice that exists and recently discovered planet nine exists here. This planet nine in Kuiper belt is 10 times the mass of earth and 5000 time the mas of Pluto.

Since Pluto has left orbit of the sun. It is not considered as planets as any more again it is very small and size. It is beyond the Kuiper belt. Therefore it is considered as dwarf planets or planetoids. Other planetoids are include Ceres and Eris.

Official classification explains planets that have 27 % more mass as compared to Pluto then only would be officially discovered as planets.

Now Ceres is a largest object in asteroid between Mars and Jupiter and Ceres is also considered as a dwarf plants.

The other important dwarf planets that was discovered are Eris in 2003. UB313 is 10th planet or largest dwarf plants which discovered till date. As said you have Kuiper belt and before Kuiper belt, it was known as OORT cloud and this OORT cloud is considerably made of Ice which is composed mainly of ammonia, methane and water and later on a it was discovered that Kuiper belt exists beyond Neptune and is similar in many respect to asteroids belt that exists between Mars and Jupiter.


  • Shape – Geoid or Oblate Spheroid
  • 3rd nearest to sun
  • 5th largest planet
  • Age: 4.54 billion years old
  • Chemical composition of Crust – Silica, alumina, lime
  • Earth՚s mass - Iron (32 %) , Oxygen (30 %) , Silicon (15 %)
  • Earth՚s Crust – 47 % Oxygen
  • Rotation & Revolution
  • Earth՚s perihelion (closest) around 3 January & aphelion around 4 July.

Now understanding the earth. When will you talk about earth first understand the shape of the earth. The shape of earth is not perfect sphere. It is Oblate Spheroid shape. It is Geoid in nature.

You will see that you have polar diameter and the equatorial diameter and there is different between equatorial diameter 12,756 km and you have polar diameter 12,714 km that is 42km more width compared to height and it is flatter as a poles.

We know earth is made of crust, core and mantle. Outer more layer is crust and inner part is known as core and between core and crust is called mantle. Crust has maximum proportion of silica followed by alumina, followed by lime. So have highest proportion of silica.

When we talk about mass of the earth the whole earth it is Iron which is highest at 32 % then followed by oxygen 30 % and silica 15 % the crust itself outer crust which is silica and alumina but both of this compounds have oxygen & so 47 % oxygen.

Earth has two motions: Rotation & Revolution. Rotation means spinning on its axis and Revolution means taking one complete round around the sun. Revolution leads to formation of seasons while Rotation leads to day and night.

Earth rotates around the sun in an elliptical path. It some point it is closed to earth, the point is a closest to earth is 3 January and farthest is 4 July. Now reason where is closest to the earth՚s is known as a perihelion. Helion ″ means ″ Sun ″ . Perihelion is closest to the sun and other aphelion which is farthest from this the sun.

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