Why Pluto is not a planet?
- Pluto was first discovered by Clyde Tombaugh in 1930
- The redefinition of the planet by the IAU on 24th August 2006 states that the solar system Planet is a celestial body. The association delivers three basic rule for planets.
- It is in orbit around the sun.
- It has sufficient mass so that it assumes a hydrostatic equilibrium shape (nearly sphere)
- Its orbit does not interrupt the neighbour planets
- A non-satellite planet pluto obeys the first two rules but it does not fulfil the third rule so it considers as a dwarf planet.