Searching for the Ninth Planet: Solar System Migration

[wolram]

Does our solar system host a Ninth planet, If so has our solar system under gone planetary migration?

 

[Drakkith]

Does our solar system host a Ninth planet

Not under the current definition of 'Planet':

The International Astronomical Union (IAU) defined in August 2006 that, in the Solar System, a planet is a celestial body which:

1. is in orbit around the Sun,
2. has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
3. has "cleared the neighborhood" around its orbit.

 

[Ophiolite]

Examination of the orbital characteristics of Trans-Neptunian bodies suggested to Trujillo & Shepherd (2014) that these characteristics were the likely consequence of a massive body of super-Earth dimensions. Its existence has not been confirmed by direct observation and not all researchers agree with the interpretation of the data. Such a body would certainly meet the first two definitions of a planet as noted by Drakkith, but it would be difficult to determine whether or not it met the third. (The third requirement was always, in my view, a poor constraint, constructed to eliminate Pluto, Sedna and the like, but not well conceived to deal with novel discoveries.)

A more recent discussion of the concept can be found in this paper by Khain et al (2018).

In regard to migration practically all hypotheses for solar system formation include migration, but the details (timing and bodies involved) differ from explanation to explanation.

 

[alantheastronomer]

There's still a discrepancy in the orbit of Neptune that the discovery of Pluto was supposed to solve yet didn't...so there's still that unanswered question!

 

[Vanadium 50]

There's still a discrepancy in the orbit of Neptune that the discovery of Pluto was supposed to solve yet didn'

Astronomy magazine disagrees with you: http://www.astronomy.com/magazine/ask-astro/2017/01/planet-nine-effect

I have to ask - are you actually an astronomer? That is, someone paid to do astronomy? Your message seems to be authoratitative, but often contradict what I know about astronomy (and I have only a MS in that field, and even that is in "physics and astronomy". My PhD is in physics only)

 

[alantheastronomer]

Actually, I'm an astrophysicist, but that was too many characters for physics forums to accept as my name, so I shortened it. I'm currently not employed nor affiliated with any institution. I went to grad school in the early eighties before Voyager II reached Neptune, so I was unaware that the discrepancy had been resolved - thanks for alerting me to this development!