Since this is a Science question, I put it in GQ, even though I expect that there may be differing opinions on this topic.
I was watching an episode of How the Universe Works and the very distinguished astronomers and physicists in the show seem to agree that there exists a planet, about 10 times the size of Earth, out in the Kuiper Belt.
I may be leaving details out, but the premise seems to be that several objects in the Kuiper Belt have odd orbits that can only be explained by a massive object influencing them. Additionally, computer modeling of the creation of the Solar System, and the current orbits of the 8 known planets, only work with the existence of a 9th planet.
Apparently, since the planet is estimated to have a very elliptical orbit, and at certain points is over 10 billion miles away from the sun (over 1,000 times the earth-sun distance), it is very difficult to locate.
While I love the show, there are times that it is somewhat sensationalist, likely to attract more viewers. So, what is the opinion of our SDMB experts?
I was going to say “Astronomers aren’t putting their money on that yet”, but then I looked for a more qualified opinion and discovered that Phil Plait, my go to qualified opinion on astronomy, is in fact putting his (rhetorical) money on Planet 9.
Still, in this 2019 post he isn’t saying that wouldn’t still be a gamble: Does planet 9 exist?
There is a ninth planet. It’s called, “Pluto”. It even has a moon of its own, but those who callously gave Pluto the boot remain unmoved by that fact and the fact that it was a planet for 76 years.
Then Pluto is the 10th planet, the 5th planet is Ceres but those who callously gave Ceres the boot remain((ed) they are all dead by now) unmoved by the fact that it was a planet for 50 years.
As you can see from Pluto’s quandary, it depends what you call a real planet. Is Ceres a planet? How big does it have to be? How circular/concentric does the orbit have to be?
the article linked is not terribly clear what they mean by “aligned long axes” - I presume they mean the long axes are close to the same plane. That may be a very rare coincidence, but only if that’s the case for everything, not just for the few bodies selected.
As far as Pluto being a planet because it has its own moon, meet Ida:
Ida is less than 40 miles wide at its widest point, and I don’t think anyone would call it a “planet”. It very much looks like the sort of thing Han Solo would have to dodge out of the way of. But, see that smaller thing off to the right? That’s Ida’s moon, Dactyl. Turns out that asteroids with moons aren’t even all that uncommon–we’ve discovered several hundred of them.
Yet another reason why I support classing objects as rockballs, gasballs, and iceballs, rather than lumping all three into one “planet” category. Mercury, Venus, Earth, Luna, Mars, and Ceres are all rockballs. Jupiter, Saturn, Uranus, and Neptune are all gasballs. Pluto is one of the largest iceballs (not the largest; Eros at least is larger, and probably several others as well that we haven’t discovered yet), but there are many, many other iceballs.
