Is Pluto a planet and when was it discovered?
Pluto was discovered on February 18, 1930. It was a planet until 2006 when the scientific term ‘planet’ was redefined. For an object to be a planet: 1) The object must be in orbit around the Sun. 2) The object must be massive enough to be a sphere by its own gravitational force. More specifically, its own gravity should pull it into a shape of hydrostatic equilibrium. 3) It must have cleared the neighbourhood around its orbit. Pluto does not meet the last criteria so it was renamed to be a “dwarf planet” along with several other kuiper belt objects and asteroids.
