Difference between revisions of "Dwarf planet"
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* has sufficient mass to possess a spheroid-shape | * has sufficient mass to possess a spheroid-shape | ||
* has '''not''' "cleared the neighbourhood" around its orbit. | * has '''not''' "cleared the neighbourhood" around its orbit. | ||
| − | Dwarf planets are not 'true' [[planet|planets]] only because of the last criterion, which says that a 'true' | + | Dwarf planets are not 'true' [[planet|planets]] only because of the last criterion, which says that a 'true' planet has "cleared the neighbourhood" in its orbital zone, meaning that there exist no objects of substantial mass other than natural satellites near its orbit. |
== FAQs == | == FAQs == | ||
=== Why isn't Pluto a planet? === | === Why isn't Pluto a planet? === | ||
| − | [[Pluto]] was excluded from the [[International Astronomical Union|IAU]] definition of a planet due to a redefinition of the criteria for being a planet in 2006. This attracted some controversy after it defined the [[solar system]] to have 8 planets instead of 9, however it is now generally accepted that [[Pluto]] is a dwarf planet. | + | [[Pluto]] was excluded from the [[International Astronomical Union|IAU]] definition of a planet due to a redefinition of the criteria for being a planet in 2006. This attracted some controversy after it defined the [[solar system]] to have 8 planets instead of 9, however, it is now generally accepted that [[Pluto]] is a dwarf planet. |
Revision as of 10:14, 4 January 2020
Explanation
A dwarf planet is an object that is not a satellite and by the IAU definition:
- is in orbit around the Sun
- has sufficient mass to possess a spheroid-shape
- has not "cleared the neighbourhood" around its orbit.
Dwarf planets are not 'true' planets only because of the last criterion, which says that a 'true' planet has "cleared the neighbourhood" in its orbital zone, meaning that there exist no objects of substantial mass other than natural satellites near its orbit.
FAQs
Why isn't Pluto a planet?
Pluto was excluded from the IAU definition of a planet due to a redefinition of the criteria for being a planet in 2006. This attracted some controversy after it defined the solar system to have 8 planets instead of 9, however, it is now generally accepted that Pluto is a dwarf planet.