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Perhaps one of the more interesting things in this article was the depiction of Haumea [0]. I had no clue planets could have an elliptical shape. Pretty cool. A

Perhaps one of the more interesting things in this article was the depiction of Haumea [0]. I had no clue planets could have an elliptical shape. Pretty cool. Apparently it hasn't been directly observed, but it's shape has been calculated from its "light curve". [0](https://en.wikipedia.org/wiki/Haumea https://en.wikipedia.org/wiki/Haumea)

abstrakraft 10y ago
>> I had no clue planets could have an elliptical shape. They can't, as one of the defining characteristics of a planet is having enough mass to be rounded under it's own gravity. Dwarf planets have no such restriction.
- gnoway 10y ago
  Earth is elliptical - an oblate spheroid - so I would say they can.
  - bronson 10y ago
    Yes, the Earth is an oblate spheroid rounded by its own gravity. Despite your tone, you seem to be agreeing.
- Retric 10y ago
  Almost, if they spin they will bulge in the center.
- cgriswald 10y ago
  The reality is we still don't have good definitions for these objects. > They can't, as one of the defining characteristics of a planet is having enough mass to be rounded under it's own gravity. The problem here is that "rounded" simply means "roughly spheroid". It's an imprecise term with no rules governing how far from a sphere the objects can deviate and still be considered planets or dwarf planets. > Dwarf planets have no such restriction. It is that restriction that separates dwarf planets from large asteroids. The distinction between planet and dwarf planet has to do with whether or not the object has cleared its orbit of other debris.
- the8472 10y ago
  That's incorrect. The dwarf planet designation only removes the "must have cleared its orbit" restriction that planets have. They must still be in hydrostatic equilibrium. Non-spherical objects can still be in hydrostatic equilibrium due to centrifugal forces being anisotropic. https://en.wikipedia.org/wiki/Dwarf_planet#History_of_the_concept https://en.wikipedia.org/wiki/Dwarf_planet#History_of_the_co...

abstrakraft 10y ago

>> I had no clue planets could have an elliptical shape. They can't, as one of the defining characteristics of a planet is having enough mass to be rounded under it's own gravity. Dwarf planets have no such restriction.

gnoway 10y ago
Earth is elliptical - an oblate spheroid - so I would say they can.
- bronson 10y ago
  Yes, the Earth is an oblate spheroid rounded by its own gravity. Despite your tone, you seem to be agreeing.
Retric 10y ago
Almost, if they spin they will bulge in the center.
cgriswald 10y ago
The reality is we still don't have good definitions for these objects. > They can't, as one of the defining characteristics of a planet is having enough mass to be rounded under it's own gravity. The problem here is that "rounded" simply means "roughly spheroid". It's an imprecise term with no rules governing how far from a sphere the objects can deviate and still be considered planets or dwarf planets. > Dwarf planets have no such restriction. It is that restriction that separates dwarf planets from large asteroids. The distinction between planet and dwarf planet has to do with whether or not the object has cleared its orbit of other debris.
the8472 10y ago
That's incorrect. The dwarf planet designation only removes the "must have cleared its orbit" restriction that planets have. They must still be in hydrostatic equilibrium. Non-spherical objects can still be in hydrostatic equilibrium due to centrifugal forces being anisotropic. https://en.wikipedia.org/wiki/Dwarf_planet#History_of_the_concept https://en.wikipedia.org/wiki/Dwarf_planet#History_of_the_co...