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News
- Group of Planetary physicist questions IAU on removal of Pluto as a planet.
Important fact
- In 2006 the IAU removed the Pluto planetary status and designated it as a Dwarf Planet.
Argument proposed by IAU to remove planetary tag
- A planet must be an object which independently orbits the Sun (this means moons can’t be considered planets, since they orbit planets) but Pluto is affected by Neptune’s gravity and shares its orbit with the frozen object in the Kuiper belt.
- A planet must have enough mass that so its own gravity pulls it into a roughly spheroidal shape. But Pluto is not large enough to “dominate” its orbit, so it is not a planet.
- It must be large enough to “dominate” its orbit (i.e. its mass must be much larger than anything else which crosses its orbit). But in case of pluto Charon (Pluto’s moon) is too large to be called a satellite and almost carries the same mass as Pluto.
- Arguments proposed by Physician
- Dwarf planets need to satisfy only the first two conditions.
- Identifying the planet was based on reasoning and observations only.
