Difference between revisions of "Dwarf planet"

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m Why isn't Pluto a planet?
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== 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.
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[[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 10:15, 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.