Pluto was stripped of its status as a planet today when scientists from around the world redefined it as a "dwarf planet" to leave just eight classical planets in the solar system.
Pluto - not a planet
Discovered in 1930, Pluto has traditionally been considered the ninth planet, and furthest from the sun, in the solar system.
However, the first definition of a planet - approved after a heated debate among some 2,500 scientists and astronomers in Prague - drew a clear distinction between Pluto and the other eight planets.
The need to define what it takes to be a planet stems from technological advances that enable astronomers to look further into space and to measure more precisely the size of celestial bodies in our solar system.
In addition to the categories of "planet" and "dwarf planet", the definition creates a third category to encompass all other objects, except satellites, to be known as small solar system bodies.