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Articles like this pop out often and they do not make sense. There are constantly news about "New Dwarf Planets" and they are almost all wrong. First of all, t

by 1ris 10y ago

Articles like this pop out often and they do not make sense. There are constantly news about "New Dwarf Planets" and they are almost all wrong. First of all, the definition of "dwarf planets" does not make any sense. It was introduced because of the historic mistake to classify Pluto as a planet and americans being emotional about correcting that. The definition is "a dwarf planet is asteroid the IAU considers to be popular enough". Right now there are five objects that fullfill these criteria: Ceres, Pluto, Eris, Makemake and Haumea. This new found is obviously not in this list, just like hundreds of other objects that are like other so called "dwarf planets". The correct headline is: "New asteroid found". Sounds way less spectacular. But the truth is there are not only five know objects like this, but way, way more.

restalis 10y ago
Quoting from Wikipedia¹: "[asteroid and planetoid terms have been applied to] any astronomical object orbiting the Sun that did not show the disc of a planet and was not observed to have the characteristics of an active comet", which means we don't quite know yet if it's an asteroid/planetoid or a dwarf planet. You may be right about the introduction of "dwarf planet" having something to do with Americans being emotional about Pluto, but the diversification of terms coming as a result of increased amount of knowledge in a domain is something natural. ¹ https://en.wikipedia.org/wiki/Asteroid https://en.wikipedia.org/wiki/Asteroid
- 1ris 10y ago
  No, we know for sure it's not a draw planet because it's not in the IUA's list of dwarf planets. Just like literally hundreds of objects that have dwarf planet properties, but are not as popular. And I'm not against diversification of terms at all. It's just that draw planet seems to be a quite arbitrary term used for arbitrary objects.
  - noselasd 10y ago
    Which are these hundreds of objects are you referring to ? It seems to me most of the currently known larger objects arn't in hydrostatic equilibrium, and thus not qualified to be called a dwarf planet.
    - 1ris 10y ago
      > is estimated that there may be 200 dwarf planets in the Kuiper belt of the outer Solar System[1][needs update] and possibly more than 10,000 in the region beyond. https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets
      - qb45 10y ago
        You have every right to claim that IAU is slow in recognizing newly discovered dwarf planets, especially if they actually are, but please support this with some list of objects verified to satisfy DP definition and not yet recognized by IAU. What you gave is some Wikipedia list of objects "most likely to be dwarf planets" and some estimate of the number of undiscovered dwarf planets, which has nothing to do with IAU liking or not liking these objects. Furthermore, from "dwarf planet" on Wiki: only two of these bodies, Ceres and Pluto, have been observed in enough detail to demonstrate that they actually fit the IAU's definition. Though if one reads further, The IAU accepted Eris as a dwarf planet because it is more massive than Pluto. They subsequently decided that unnamed trans-Neptunian objects with an absolute magnitude brighter than +1 (and hence a diameter of ≥838 km assuming a geometric albedo of ≤1) are to be named under the assumption that they are dwarf planets. so maybe you are right about IAU and their list of dwarf planets being a mess.
        SamBam 10y ago
        It seems pretty reasonable. Basically, barring further evidence, all the evidence points to Eris as being a dwarf planet, because objects larger than Pluto almost certainly meet the other criteria. The IAU is allowing other object to be listed as dwarf planets if it's a very strong likelihood that they are, without having to send a probe to each one.
kobeya 10y ago
This is factually incorrect. A dwarf planet is a planetoid that has sufficient gravity to overcome the crushing point of the material that makes it up, and therefore has spherical shape. It's unclear to me whether this new planetoid is of sufficient size and makeup to be spherical, and indeed, it sounds like its discoverers are unsure too. But there is definitely a clear dividing line between the two that has absolutely nothing to do with popularity.
lmm 10y ago
It was not a mistake, and it was not america-specific. The "clears its orbit" criterion is exceedingly difficult to measure (it was evidently very hard to apply within the solar system; it's going to be impossible to apply outside it) and leads to absurdities (the same body may or may not be a planet depending on where it happpens to be). The distinction between bodies in hydrostatic equilibrium and smaller bodies is clear, natural and valuable; the distinction between bodies that have cleared their orbit and bodies that have not is none of those things.

by 1ris 10y ago

restalis 10y ago

Quoting from Wikipedia¹: "[asteroid and planetoid terms have been applied to] any astronomical object orbiting the Sun that did not show the disc of a planet and was not observed to have the characteristics of an active comet", which means we don't quite know yet if it's an asteroid/planetoid or a dwarf planet. You may be right about the introduction of "dwarf planet" having something to do with Americans being emotional about Pluto, but the diversification of terms coming as a result of increased amount of knowledge in a domain is something natural. ¹ https://en.wikipedia.org/wiki/Asteroid https://en.wikipedia.org/wiki/Asteroid

1ris 10y ago
No, we know for sure it's not a draw planet because it's not in the IUA's list of dwarf planets. Just like literally hundreds of objects that have dwarf planet properties, but are not as popular. And I'm not against diversification of terms at all. It's just that draw planet seems to be a quite arbitrary term used for arbitrary objects.
- noselasd 10y ago
  Which are these hundreds of objects are you referring to ? It seems to me most of the currently known larger objects arn't in hydrostatic equilibrium, and thus not qualified to be called a dwarf planet.
  - 1ris 10y ago
    > is estimated that there may be 200 dwarf planets in the Kuiper belt of the outer Solar System[1][needs update] and possibly more than 10,000 in the region beyond. https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets
    - qb45 10y ago
      You have every right to claim that IAU is slow in recognizing newly discovered dwarf planets, especially if they actually are, but please support this with some list of objects verified to satisfy DP definition and not yet recognized by IAU. What you gave is some Wikipedia list of objects "most likely to be dwarf planets" and some estimate of the number of undiscovered dwarf planets, which has nothing to do with IAU liking or not liking these objects. Furthermore, from "dwarf planet" on Wiki: only two of these bodies, Ceres and Pluto, have been observed in enough detail to demonstrate that they actually fit the IAU's definition. Though if one reads further, The IAU accepted Eris as a dwarf planet because it is more massive than Pluto. They subsequently decided that unnamed trans-Neptunian objects with an absolute magnitude brighter than +1 (and hence a diameter of ≥838 km assuming a geometric albedo of ≤1) are to be named under the assumption that they are dwarf planets. so maybe you are right about IAU and their list of dwarf planets being a mess.
      - SamBam 10y ago
        It seems pretty reasonable. Basically, barring further evidence, all the evidence points to Eris as being a dwarf planet, because objects larger than Pluto almost certainly meet the other criteria. The IAU is allowing other object to be listed as dwarf planets if it's a very strong likelihood that they are, without having to send a probe to each one.

kobeya 10y ago

This is factually incorrect. A dwarf planet is a planetoid that has sufficient gravity to overcome the crushing point of the material that makes it up, and therefore has spherical shape. It's unclear to me whether this new planetoid is of sufficient size and makeup to be spherical, and indeed, it sounds like its discoverers are unsure too. But there is definitely a clear dividing line between the two that has absolutely nothing to do with popularity.

lmm 10y ago

It was not a mistake, and it was not america-specific. The "clears its orbit" criterion is exceedingly difficult to measure (it was evidently very hard to apply within the solar system; it's going to be impossible to apply outside it) and leads to absurdities (the same body may or may not be a planet depending on where it happpens to be). The distinction between bodies in hydrostatic equilibrium and smaller bodies is clear, natural and valuable; the distinction between bodies that have cleared their orbit and bodies that have not is none of those things.