Two studies published on arXiv have identified the hypothetical ~10 Earth mass "Planet Nine" as an explanation for the tilt of the solar system:
Two recent studies have shown that the existence of a mysterious, hypothetical Planet Nine could explain why the planets in our Solar System don't fully line up with the Sun. Researchers have been speculating about a ninth planet since January this year, and these latest studies add more weight to the hypothesis that, at some point in time at least, there was an extra planet orbiting our Sun. In fact, if Planet Nine does exist (or did), it would help to explain something that scientists have puzzled over for decades - why the Solar System is tilted.
What does that mean? Well, basically, all of the main eight planets that orbit our Sun do so on the same plane, making the Solar System look like a disc. The problem is that the Sun spins at a different angle, with its axis roughly 6 degrees off from the rest of the planets.
In the past, researchers have attempted to explain this slant by blaming the temporary tug of a passing star, or interactions between the Sun's magnetic field and the disc of dust that formed our planets. But none of these hypotheses have fully accounted for the misalignment. But now the two new studies – [completely independent] from one another in the US and France – show that the existence of Planet Nine could explain the tilt.
Solar Obliquity Induced by Planet Nine
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Medieval astronomical records, such as the Bayeux Tapestry, could help narrow down the location (or at least infer the existence) of the hypothetical Planet Nine:
Scientists suspect the existence of Planet Nine because it would explain some of the gravitational forces at play in the Kuiper Belt, a stretch of icy bodies beyond Neptune. But no one has been able to detect the planet yet, though astronomers are scanning the skies for it with tools such as the Subaru Telescope on Hawaii's Mauna Kea volcano.
Medieval records could provide another tool, said Pedro Lacerda, a Queen's University astronomer and the other leader of the project.
"We can take the orbits of comets currently known and use a computer to calculate the times when those comets would be visible in the skies during the Middle Ages," Lacerda told Live Science. "The precise times depend on whether our computer simulations include Planet Nine. So, in simple terms, we can use the medieval comet sightings to check which computer simulations work best: the ones that include Planet Nine or the ones that do not."
Also at Queen's University Belfast.
Related: "Planet Nine" Might Explain the Solar System's Tilt
Planet Nine's Existence Disfavoured by New Data
Study of ETNOs Supports Planet Nine's Existence
Passing Star Influenced Comet Orbits in Our Solar System 70,000 Years Ago
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @07:08AM
Nibiru lives....
(Score: 2) by choose another one on Tuesday July 26 2016, @03:02PM
No, that is planet X, as in _ten_. This is planet _nine_ we are talking about.
Or Pluto II "this-ones-big-enough".
(Score: -1, Troll) by Anonymous Coward on Tuesday July 26 2016, @07:09AM
I thought Jupiter and Saturn were the Solar System's tits. Saturn has nipple rings. The Big Red Spot is breast cancer.
(Score: 4, Informative) by FatPhil on Tuesday July 26 2016, @08:09AM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: -1, Troll) by Anonymous Coward on Tuesday July 26 2016, @08:11AM
Yes, thank you, for reminding us all that science is as incestuous as two brothers sucking each others cocks.
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @11:00AM
They may be attached to the same organism, and share a lot in common, but my butt cheeks can certainly operate independently.
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @12:10PM
Really? So one can move to New York, while the other moves to Seattle?
(Score: 1) by cbiltcliffe on Tuesday July 26 2016, @03:02PM
Hey, cool it. He's got a really fat ass, but it's still not polite to point it out!
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @12:18PM
That's about the gist of their theory too. They explain the "tilt" by blaming the 9th planet, which is also tilted... So it's tilted because one of the planets are tilted. And god exists because it says so in the bible which he wrote.
(Score: 2, Offtopic) by donkeyhotay on Tuesday July 26 2016, @02:19PM
Planet nine is Pluto!
(Score: 1) by cbiltcliffe on Tuesday July 26 2016, @03:00PM
I was just thinking the same thing:
"We had a planet nine, until you idiots decided to reclassify it as a 'dwarf planet'."
(Score: 2) by Taibhsear on Tuesday July 26 2016, @03:52PM
"We had a planet nine, until you people with infinitely more experience in studying celestial bodies than me decided to reclassify it as a 'dwarf planet'."
Either we have 8 planets or over 200 [space.com]. Which do you think is easier to memorize in class? Even if we called all of them planets the teachers would just call the 8 original ones "greater planets" or the other dwarfs something else so it would be easier to differentiate between them. People need to stop being so butthurt about something they have no skin in the game for.
(Score: 3, Funny) by takyon on Tuesday July 26 2016, @03:59PM
But the Pluto colony will get less funding if Pluto is not recognized as a planet.
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(Score: 2) by bob_super on Tuesday July 26 2016, @04:46PM
> Which do you think is easier to memorize in class?
I'm amused that you believe major scientific classifications are based on keeping the numbers low enough to remember the list in class...
Maybe we should have mountains, insects or space objects like the colors in the early Unix GUIs: you only get 256, and it gets remapped when you move around.
(Score: 2) by Taibhsear on Tuesday July 26 2016, @08:32PM
So do you feel we should arbitrarily ignore what definitions we set for the planets in order to appeal to the general populations' feelings on Pluto being "left out"? Because that seems to be the only reason people want Pluto to still be a planet. If people are annoyed that this new hypothetical planet is called "Planet Nine" instead of "Planet Ten" (to include Pluto) then they should really be wanting to call it "Planet 209" if we are going by the alternate planetary definition that includes dwarf planets like Pluto. Let's at least be consistent here.
(Score: 2) by bob_super on Tuesday July 26 2016, @09:25PM
Did you read my comment? I'm pretty sure I implied that scientific classifications are not to be related to the general public's feelings...
Going by average distance from the Sun, Pluto IS planet 10 (Ceres is 5). This new one might be planet 35 or 173 for all I care. Give it a name when it's been characterized, but until then it's either named after the year of discovery or requires a more consistent name than "planet 9, 10". Putting the dwarf planets in a separate category is bound to cause an issue sooner rather than later, when we discover the next very distant one that doesn't fit.
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @11:04PM
Yes, let's be consistent by using a horrible definition that was not built on its merits, but simply railroaded through for political reasons. Then, to avoid obvious confusion, we will call things that aren't planets "dwarf planets". But dwarf planets are not planets, even though they're called planets, which they're not.
And while you're pretending to play the condescending scientist, what do we call the thousands of "exoplanets" that have been found? They're surely not planets, because by Official Decree, a planet must be in orbit about the Sun. The thousands that we know of, and the un-countable number that are out there, are not planets by definition.
(Score: 1) by toddestan on Thursday July 28 2016, @02:32AM
The definition that seems to make the most sense is that the object has reached hydrostatic equilibrium, there's no nuclear fusion going on (because then it's a star), and it doesn't orbit another planet (because then it's a moon). Speaking of moons, Jupiter has a lot of moons, but I can guarantee that schoolkids are only taught taught the name of the four Galilean moons even though they're taught that Jupiter has many moons.
What's arbitrary is requirement that a planet has "cleared its orbit". What does that even mean? There's a pretty good argument that Neptune isn't a planet because it hasn't cleared it's own orbit, depending on what you want to call "cleared". This could be an even bigger problem for this "Planet Nine". It seems that the only purpose of this poorly worded requirement was only thrown in to exclude objects like Pluto. And lets not even get into the definition requiring a planet orbit the Sun (yes, the Sun, with a capital 'S'. This means that by definition, there are only 8 planets in the entire Universe! Sorry Kepler...).
(Score: 2) by tangomargarine on Tuesday July 26 2016, @05:48PM
People need to stop being so butthurt about something they have no skin in the game for.
Who *would* have "skin in the game"? This argument doesn't work in academic contexts like this.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 2) by Taibhsear on Tuesday July 26 2016, @08:42PM
My original post is referring to the comment that the people in the International Astronomical Union that reclassified Pluto as a dwarf planet are idiots for doing so, which I disagree with. I am making the assumption that the poster was not, in fact, involved in the astronomical community nor a member in the IAU while discussing the definitions and/or the reclassification and thus would have no skin in the game as the result would have little to no impact on the person's life or work. Therefore their disdain for the IAU's decision is misplaced, misguided, uncalled for, and/or irrelevant.
(Score: 2) by tangomargarine on Tuesday July 26 2016, @09:20PM
Yes, I know what you're saying. I don't see how whether you call it a "planet" or "dwarf planet" has a significant impact on *anyone*, including scientists.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @04:55PM
The traditional name is Planet X for a reason...
(Score: 2) by weeds on Tuesday July 26 2016, @02:58PM
I didn't read the paper. Does it discount the possibility that the sun was struck and absorbed something whose orbital axis was askew from the sun? If the earth managed to degrade in its orbit before the sun ran out of fuel, the angular momentum of the earth and sun would be conserved. If the earth's path is a few degrees off of he sun's rotation, the sun (now with the additional mass of the earth) would have a slightly different angle to it's axis. Owing to conservation of angular momentum, isn't that a possible way that the axis of rotation could be off? Certainly it would have to be one pretty big object or many smaller incidents.
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(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @03:37PM
The article said that Planet Nine could explain the tilt, but that this does not prove the existence of the planet, nor does it rule out the many other theories that have been put forward.
(Score: 2, Informative) by laserfusion on Tuesday July 26 2016, @06:09PM
It is believed to have a mass of 5-20 earths and the orbit is 250 AU or more, and highly elliptical.
(By comparison, Neptune has a mass of 17 earth masses, and Pluto is at a distance of 30 - 50 AU.)
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @06:11PM
pluto was demoted in a conspiracy by the lizard people, to hide the fact that this would be Planet X.