Solar System

Solar System Important Facts:

  • Sun account for 99.85% of mass of the solar system. It continuously gives us energy in the form of Visible light, infra-red, ultra-violet, x-rays etc.
  • The period of revolution of sun around the galactic centre is 250 million years and is called as cosmotic year or galactic year.
  • Like all other stars sun is mainly composed of Hydrogen and Helium. Nuclear fusion in the core of sun is a source of all energy.
  • The glowing surface of sun that we see is called photosphere.
  • Diameter of sun is 100 earth diameters.
  • Core temperature = 15 million degree centigrade.
  • Surface temperature = 6000 degree centigrade.
  • Sun rotation time = 25 days.
  • Age = 5 billion years.
  • Composition of sun- Helium(26.5%), Hydrogen(71%), Rest(2.5%).

Terrestrial Planets: 

  • Mercury, Venus, Earth, Mars.
  • These are earth like planets which have dense rocky body and also called as inner planets.

Jovian Planets:

  • Jupiter, Saturn, Uranus, Neptune.
  • Means Jupiter like which are gaseous, gigantic, having large satellite families and high rotational velocities. These are also called as outer planets.


  • Called as swiftest planet, low atmosphere and has a crater surface.
  • It has maximum diurnal range of temperature.
  • Has the shortest year.


  • It is second only to the moon in brilliance in the night sky.
  • Closest to Earth.
  • Morning star, evening star and also the brightest star.
  • Twin of earth because of its similar size, density and mass.
  • Similar year length as of earth.
  • Its a planet where length of day is longer incomparison to the length of year.
  • Days are 243 earth days and year length 224.7 days.
  • All planets rotates from west to east except for U-V (Uranus & Venus).
  • Venus rotates from east to west so here sun rises from the west and sets in the east on contrary Uranus tumbles down from north to south.
  • Slowest rotation.
  • It is the hottest planet (atmosphere contain 97% CO2).


  • It is called as the blue planet because of presence of water.
  • Densest of all the planets and is unique for the presence of higher form of life.


  • It is called as the red planet.
  • It has evoked greatest interest than any other planet.
  • It has two moons named as Phobos and Demos (Smallest satellite).
  • It has the same angle of inclination as that of earth and has the same length of day as that of earth.
  • There is a possibility of life on mars and habitability by humans and is being extensively probed.


  • Known as lord of the heaven.
  • Largest planet in our solar system.
  • The zone / region between Mars & Jupiter is known as Asteroid belt.
  • Fastest rotational time = 9 hr 55 minutes.
  • Important satellites- Europa, Ganymede (largest satellite) and heaviest of all satellite in the solar system.


  • Known as allegiant planet.
  • Second largest and is surrounded by a set of seven rings which are made up of primordial dust and ice particles. It has more prominent ring than Jupiter.
  • Largest satellite of Saturn is titan.

Uranus and Neptune:

  • These are called as jovians twins and these are better twins in comparison to earth and venus.
  • Beside being similar in size, they appear pale greenish blue in colour because of the presence of methane in the atmosphere.
  • The largest satellite of Neptune is triton.
  • Neptune has a great depression and is called as the grey dark spot and is of earth size.
  • Important satellite of uranus is Mirand.
  1. Closest star to Earth – Sun.
  2. Closest star to solar system – Proxima Centauri also called as Alpha Centauri.
  3. Brightest star outside solar system – Sirius also called as dog star.
  4. Brightest star – Venus.
  5. Astronomical Unit – It is the mean distance between the Earth and the Sun. It is used to measure distance within the solar system.
  6. Light Year – Distance travelled by light in vacuum for a period of one year.
Indus Valley CivilizationPratihara and Rashtrakutas
Mauryan Empire Important FactsChola Empire
Pre-Gupta PeriodThe Mughal Empire (1556-1707)
Harshavardhana or Harsha (606-647 A.D.)Emergence of Regional States in India– NIOS

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