- Historical event:
- 24 August 2006
- The total number of planets was reduced from nine to eight when Pluto was removed from the list of planets. In some world cities, demonstrations were organized against Pluto’s exclusion from the “planet club”. But the mentioned decision has remained in force ever since.
On this day in 2006, the International Astronomical Union (IAU) decided to exclude Pluto from the list of planets.
Therefore, it became a so-called dwarf planet. That was a highly controversial decision, and demonstrations were organized against it in some world cities.
Namely, Pluto had been considered a planet since 1930, when it had been discovered; it was a 76-year-old tradition.
The total number of planets was reduced from nine to eight when Pluto was removed from the list of planets. All textbooks, encyclopedias, and other literature had to be changed as well as museums, observatory equipment etc.
Namely, many Solar System objects were discovered, and they had weight and other characteristics similar to Pluto.
There were indications that other objects would also be discovered, and there were allegedly two options: either to put new objects on the list of planets (according to the principle of equality with Pluto, they belonged there) or to exclude Pluto. After several discussions, the International Astronomical Union decided to exclude Pluto.
Therefore, it became a so-called dwarf planet. There are four other objects which are known as dwarf planets: Ceres, Haumea, Makemake, and Eris.
It is interesting to note that Eris has a greater mass than Pluto. There have been many criticisms regarding the term “dwarf planet”.
Namely, the International Astronomical Union stated that “dwarf planets are not planets” (on the contrary, the so-called dwarf stars are considered stars).