AkaSci 🛰️18 years ago in August 2006, Pluto was demoted in status from Planet to Dwarf Planet, as the International Astronomical Union (IAU) revised the criteria for a full-sized planet:
A planet was defined as a celestial body that
1. is in orbit around the Sun.
2. has sufficient mass to assume hydrostatic equilibrium (a nearly round shape).
3. has “cleared the neighborhood” around its orbit.
Pluto fails to meet the 3rd criterion.
https://www.iau.org/static/resolutions/Resolution_GA26-5-6.pdf
https://www.iau.org/public/themes/pluto/
#Pluto
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