'worldliness' Tagged Posts

For 76 years, Pluto was a planet. Then one day back in 2006, it wasn’t. On August 24, 2006, the International Astronomical Union (IAU) downgraded Pluto to the status of a dwarf planet based on their newly refined definition of a planet.1 The demotion of Pluto to the status of a dwarf planet was influenced by the fact that Pluto acts differently than the other eight planets. In particular, Pluto’s orbit is different. It is elliptical rather than circular and…