Very Useful RRB NTPC Geography Notes! Introduction and Solar system Only (Notes - 1)

 

Study of the universe is called Cosmology. The creation of universe was explained well by Big Bang theory. This theory was proposed by Georges Lemaitre. This theory speaks about explosion that occured 13.8 billion years ago. The existence of galaxies beyond Milkyway galaxies was discovered and reported first by Edwin Hubble.

 

Galaxies are classifie d into 3 based on their shape

1. Spiral shape (Our galaxy milkyway was spiral in shape)
   
2. Eliptical shape
   
3. Irregular shape.
   

Some important points to remember,

• Pluto had been removed from the planets list by IAU (International Astronomical Union) in 2006.
• Heliscope is the instrument to view sun.
• Time taken by sun to complete one orbit around the galactic circle is called as Cosmic year, which is 224 million years.
• 3 layers of sun are photosphere, chromosphere, and corona.
• Time taken by sun light to reach earth is 8minutes and 16.6seconds.
• Sun produce energy by Nuclear fusion.
• Sun occupies 99% of mass of solar system.
• Heliocentric model of solar system was proposed by Nicolaus Copernicus.
• Asteroids, comets and meteors are called as Interstellar debris.
• Nearest star - Proxima Centauri
• Brightest star in our sky - Sirius A
• Latest known galaxy was Canis Major Dwarf galaxy in 2003.
• Inner planets - First four planets Mercury, Venus, Earth and Mars.
• Outer or Jovian planets - Last 4 planets Jupiter, Saturn, Uranus and Neptune.

 

Mercury:

• Smallest and innermost planet
• Fastest revolution

 

Venus:

• Also known as morning and evening star.
• Rotates from east to west unlike other planets.
• Hottest and brightest planet in our solar system.
• Also known as earth's twin because of similar size, density and mass.

 

Earth:

• Blue Planet because of presence of water.
• Oblate sphere in shape.
• Densest planet in solar system.
• It complete one revolution around the sun in 365 days and 6 hours.

 

Mars:

• Red planet.
• Revolution time as like as earth.
• It has 2 natural satellites namely Phobos and Deimos.

 

Jupitar:

• Largest planet in our solar system.
• Has largest number of satellites.
• Total number of moons are 79.
• It has fastest rotational velocity.

 

Saturn:

• Second largest planet in solar system.
• It is surrounded by set of 8 rings.
• Its the least density planet.
• It has 62 natural satellite, largest one was Titan.

 

Uranus:

• Green planet - due to presence of methane.
• Rotates from north to south.
• Surrounded by faint rings and has 27 moons.
  

 

Neptune:

• Coldest planet in solar system.
• Have 14 satellites, prominant moons are Triton and Nereid.
• Have 5 faint rings and appears greenish.
• It has slowest revolution.
  

If you want to try some of the important topics and previous year questions and current affairs related things follow the below links

• Geography Notes- 2
• Geography Notes - 3
• Geography Notes - 4
• Previous year  RRB NTPC geography questions
• Previous year RRB NTPC Indian geography questions
• Previous year RRB NTPC biology questions
• Previous Year RRB NTPC Chemistry questions
• January 2020 current affairs
• February 2020 current affairs
• March 2020 current affairs