Astronomers Spot Most Distant Object In the Solar System (sciencemag.org)

sciencehabit writes: Astronomers have found the most distant known object in our solar system, three times farther away than Pluto. The dwarf planet, which has been designated v774104, is between 500 and 1000 kilometers across. It will take another year before scientists pin down its orbit, but it could end up joining an emerging class of extreme solar system objects whose strange orbits point to the hypothetical influence of rogue planets or nearby stars. In other planetary science news, UCLA professor Jean-Luc Margot has proposed a new definition of the term "planet" which would allow for the inclusion of exoplanets. His metric is laid out in an academic paper available at the arXiv.

Comments

Re: It's so ridiculously easy

[Rei]

but simulations show Mars is more than capable of doing so on its own

Mars has a tiny fraction the Stern-Levison parameter of Neptune, and Neptune hasn't gotten rid of large bodies from its "neighborhood" (they're small compared to Neptune, but not compared to Mars).

What matters is it is much more difficult to develop any formula that has some relevance to planetary dynamics which doesn't make Pluto look like an outcast, and that is the problem.

It's not a "problem" at all. The definition that most planetary scientists wanted the IAU to choose (if they felt the need to pick one at all) was hydrostatic equilibrium, meaning there would be dozens of planets. Achieving a rough hydrostatic equilibrium is a very meaningful dividing line - it means differentiation, mineralization processes, alteration of primordial materials, and so forth. It's also often associated with internal heat and, increasingly as we're realizing, a common association with subsurface fluids. In short, a body in a category of "not having achieved hydrostatic equilibrium" describes a body which one would study to learn about the origins of our solar system, while a body in a category of "having achieved hydrostatic equilibrium" describes a body one would study, for example, to learn more about tectonics, geochemistry, (potentially) biology, etc. By contrast, a dividing line of "clearing its neighborhood" - which isn't actually what half of the planets in our solar system have done - says little about the body itself.

And yes, there are many reasons why the whole process was grossly unscientific. I've first already covered the voting process above, which is absurd, especially in a day where they could have handled such a thing online. There's the obvious criticism of it being sun-centered, having no clear definition on what defines a "neighborhood" or "cleared", the pseudoscience of the planets all having cleared their own neighborhoods, the lie about how they planned to review further "dwarf planets" for inclusion (they haven't), the comparative inconsistency (really, Earth is more like Jupiter than it is like Pluto?), the atrocious name where a "dwarf X" isn't an "X", and on and on. But these are just minor points.

First off, the primary reason cited by virtually every scientist I've seen interviewed about their vote in favor of an exclusive standard over an inclusive standard is along the lines of, "It would be too hard for schoolchildren to memorize the names of all of them". This is such a blatantly unscientific standard that it doesn't even bear going into, and leads to absurd consequences when applied to other fields, such as the AMA declaring that there's only 8 bones in the human body and all others are "dwarf bones" that aren't real bones, or the USGS declaring that there's only 8 rivers in the world and all others are "dwarf rivers" that aren't real rivers, all for the purpose of making things easier for students to memorize. They decided that they wanted schoolchildren to be able to memorize the names of all the planets around the sun, and then contrived a definition of "planet" to try to make that happen. This is not science, it's idiocy.

Then there's the basic issue of scientific categorizations altogether. In every scientific field, the universe continually presents those making discoveries with a wide range of diversity. This is almost universally accepted in an inclusive manner, subdividing groups into subgroups, and subdividing those further. We will continue to find new types of planetary bodies in a wide range of diversity - large terrestrial planets, dwarf-scale planets, gas giants, ice giants, hot jupiters, super-earths, water worlds, supercomets, extremely large bodies orbiting as moons, planets without parent stars, and so forth. Rather than trying to hide diversity, science is supposed to embrace it.

Then there's the issue of the timing. For most of the history of humankind's knowledge of Ceres and Pluto, we have

Re: Does this mean??!

[Rei]

I described the process that led up to the vote, which you can easily read anywhere on the net. You can also readily find no shortage of planetary scientists complaining about it on the net. If there's any specific fact you disagree with, state it and I will reference it for you.