Beyond Neptune, a chunk of ice is orbiting the sun in the wrong direction

Beyond Neptune, a chunk of ice is orbiting the sun in the wrong direction
An artist’s concept of a trans-Neptunian object(TNOs). The distant sun is reduced to a bright star at a distance of over 3 billion miles. Credit: NASA

Beyond the orbit of Neptune, the farthest recognized-planet from our sun, lies the mysteries population known as the Trans-Neptunian Object (TNOs). For years, astronomers have been discovering bodies and minor planets in this region which are influenced by Neptune's gravity, and orbit our sun at an average distance of 30 Astronomical Units.

In recent years, several new TNOs have been discovered that have caused us to rethink what constitutes a planet, not to mention the history of the solar system. The most recent of these mystery objects is called "Niku", a small chunk of ice that takes its name for the Chinese word for "rebellious". And while many such objects exist beyond the orbit of Neptune, it is this body's orbital properties that really make it live up to the name!

In a paper recently submitted to arXiv, the international team of astronomers that made the discovery explain how they found the TNO using the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS 1). Measuring just 200 km (124 miles) in diameter, this object's orbit is tilted 110° to the plane of the solar system and orbits the sun backwards.

Ordinarily, when planetary systems form, angular momentum forces everything to spin in the same direction. Hence why, when viewed from the celestial north pole, all the objects in our solar system appear to be orbiting the sun in a counter-clockwise direction. So when objects orbit the sun in the opposite direction, an outside factor must be at play.

Beyond Neptune, a chunk of ice is orbiting the sun in the wrong direction
Artist’s impression of Planet Nine as an ice giant eclipsing the central Milky Way, with a star-like Sun in the distance. Neptune’s orbit is shown as a small ellipse around the Sun. Credit: ESO/Tomruen/nagualdesign

What's more, the team compared the orbit of Niku with other high-inclination TNOs and Centaurs, and noticed that they occupy a common orbital plane and experience a clustering effect. As Dr. Matthew J. Holman – a professor at the Harvard-Smithsonian Center for Astrophysics and one of the researchers on the team – told Universe Today via email:

"The orbit of Niku is unusual in that it is nearly perpendicular to the plane of the solar system. More than that, it is orbiting in the opposite direction of most solar system bodies. Furthermore, there are a few bodies that share the same or orbital plane, with some orbiting prograde and some orbiting retrograde. That was unexpected."

One possibility, which the team has already considered, was that this mysterious orbital pattern might be evidence of the much sought-after Planet Nine. This hypothetical planet, which is believed to exist at the outer edge of our solar system (20 times further from our sun than Neptune), if it exists, is also thought to be 10 times the size of the Earth.

Beyond Neptune, a chunk of ice is orbiting the sun in the wrong direction
Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign

"Planet Nine seems to be gravitationally influencing another nearby population of bodies that are also orbiting nearly perpendicular to the plane of the solar system," said Holman, "but those objects have much larger orbits that also come closer to sun at their closest approach. The similarity (perpendicular) nature of Niku's orbit to that of the more distant population hints at a connection."

Establishing such a connection based on the orbits of distant objects is certainly tempting, especially since no direct evidence of Planet Nine has been obtained yet. However, upon further analysis, the team concluded that Niku is too close to the rest of the solar system for its orbit to be effected by Planet Nine.

In addition, the orbits of the clustered objects that circle the sun backwards along the same 110-degree plane path was seen as a further indication that something else is probably at work. Then again, it may very well be that there is a giant planet out there, and that it's influence is mitigated by other factors we are not yet aware of.

Beyond Neptune, a chunk of ice is orbiting the sun in the wrong direction
Artist's concept of a mysterious TNO orbitting at the edge of our Solar System. Credit: ESO/L. Calçada/Nick Risinger

"The population of objects in Niku-like orbits is not long-term stable," said Holman. "We hoped that adding the gravitational influence of an object like Planet Nine might stabilize their orbits, but that turned out not to be the case. We are NOT ruling out Planet Nine, but we are not finding any direct evidence for it, at least with this investigation."

So for the time being, it looks like Planet Nine enthusiasts are going to have to wait for some other form of confirmation. But as Konstantin Batyagin – the Caltech astronomer who announced findings that hinted at Planet Nine earlier this year – was quoted as saying, this discovery is yet another step in the direction of a more complete understanding of the outer solar system:

"Whenever you have some feature that you can't explain in the outer solar system, it's immensely exciting because it's in some sense foreshadowing a new development. As they say in the paper, what they have right now is a hint. If this hint develops into a complete story that would be fantastic."

Whatever the cause of Niku's strange (or those TNOs that share its orbital pattern) may be, it is clear that there is more going on in the outer than we thought. And with every new discovery, and every new object catalogued by astronomers, we are bettering our understanding of the dynamics that are at work out there.

Credit: New Scientist

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Aug 17, 2016
orbit to be effected by Planet Nine

[grammar Nazi mode on] affected [grammar Nazi mode off]

Aug 17, 2016
"We hoped that adding the gravitational influence of an object like Planet Nine might stabilize their orbits, but that turned out not to be the case."

How about trying to consider the myriad close passes by stars, brown dwarfs and rogue planets, etc., over the last 4.5 billion years? It is thought that Scholz's star passed 0.8 ly away about 70,000 years ago. Gliese 710 is calculated to approach within 1.1 ly in about 1.3 million years, and "There is even a 1/10,000 chance of the star penetrating into the region (d < 1,000 AU) where the influence of the passing star on Kuiper belt objects is significant." https://en.wikipe...iese_710

Apologies to Mike Brown, but my money is still on "Planet 9" not existing. It has been ~7 months since the announcement and the clock is still ticking.

Aug 17, 2016
More close passes . . .

"3.8 million years ago when gamma Microscopii – a G7 giant which has two and a half times the mass of our Sun – came within 0.35-1.34 pc of our system, which may have caused a large perturbation in the Oort cloud."

http://www.univer...t-worry/

"Bailer-Jones (2014) predicts that HIP 85605 will pass within (0.3 ly) in ~332,00 years."

http://arxiv.org/...55v1.pdf

Aug 17, 2016
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Aug 17, 2016
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Aug 17, 2016
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Aug 17, 2016
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Aug 17, 2016
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Aug 17, 2016
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Aug 17, 2016
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Aug 17, 2016
@ Mark: The stochastic nature of gravitational disturbances would not stabilize orbits by regular action though. And has had virtually no effect in sculpting our system except the Oort cloud radius and composition (10 % foreign comets estimated), what can be seen. So not impossible to exclude, just unlikely.

Re PN, usually the clock wouldn't tick since it is hard to measure, c.f. how it took a century to test for gravitational waves. In this case B&B has self imposed a clock by estimating that they may eliminate all remaining PN hiding places in some 5 years, grants willing. So if they are in the middle of a successful grant procedure, which is likely, the clock may have ticked or start to tick some 20 % soon.

@BTP: Defrocking depends on the sect, I think. The Swedish lutheran church throws out economical and/or sexual predators, AFAIK. And why wouldn't they?

Aug 17, 2016
A planet whose orbital plane is nearly vertical only needs that plane to move by a few degrees for its retrograde motion to become prograde.

Aug 17, 2016
Even the second syllable accent of "baptism", from the Greek, is no longer the preferred pronunciation.


Unless it's a southern preacher talking about how we all gonna see a baptism of fire when the end of days come!

Aug 17, 2016
@TBGL, while I acknowledge B&B may yet prove to be 100% correct, some professional astronomers have made the same or similar comments that I have above. Based on recent insights, there must have been thousands, or even tens of thousands of relatively close passes by large bodies since the solar system formed. Some of them must have had an effect on orbits in the outer solar system, so the question becomes could the effect be the one detected? It is premature to make any hard conclusions about all the close passes not being the source of the strange orbits B&B detected. For all we know, B&B would have been exactly right, except that planet was dislodged by a passing star 70 million years ago.

"Does Planet Nine really exist, or is it deep space fantasy?"
http://hub.jhu.ed...y-exist/

Aug 17, 2016
Regarding Planet 9, "Greg Laughlin, an astronomer at the University of California, Santa Cruz, and one of the few scientists who knew in advance of the paper, said, "It's a very solid dynamical analysis. It's top-notch. If anybody else was making this claim, you'd have to discount it to, at best, a one-per-cent chance of being there. But the combination of Mike Brown, who has a really solid observational sense of what's out there, and Konstantin's theoretical brilliance—if it's out there, they've found it.""
- Astronomer Greg Laughlin, University of California, Santa Cruz (January 2016)

http://www.newyor...net-nine


Aug 17, 2016
While B&B may both be brilliant, I wonder if they can tell us the mean number of planets a G2-type star will gain and lose over the course of its first 4.5 billion years? To simply hand wave this possibility away as being too rare to consider is not scientific, and that is just one possible scenario. The bigger trend here is that the outer solar system is turning out to be a lot more interesting than previously thought.

Aug 18, 2016
Ordinarily, when planetary systems form, angular momentum forces everything to spin in the same direction.

Please let me know when someone actually publishes the observation with verification that a planetary system has formed somewhere in the universe. All by itself, with nary a visible helping "hand" at play.
The only REAL observation that current astronomers/cosmologists can make is that the ONE planetary system we can observe shows planets orbiting their star in the same direction. All other systems have an inferred observation and those also show the same result. There is however, ABSOLUTELY ZERO observation of a planetary system forming from scratch.
Do not be misled by the unscientific materialistic propaganda that supposedly passes for science published everywhere.

Aug 18, 2016
Ordinarily, when planetary systems form, angular momentum forces everything to spin in the same direction.

Please let me know when someone actually publishes the observation with verification that a planetary system has formed somewhere in the universe. All by itself, with nary a visible helping "hand" at play.
The only REAL observation that current astronomers/cosmologists can make is that the ONE planetary system we can observe shows planets orbiting their star in the same direction. All other systems have an inferred observation and those also show the same result. There is however, ABSOLUTELY ZERO observation of a planetary system forming from scratch.
Do not be misled by the unscientific materialistic propaganda that supposedly passes for science published everywhere.

This is so wrong on so many levels, it is hard to believe that someone would actually have posted it.

Aug 18, 2016
@ Maggnus, Exactly right. This is what Neil deGrasse Tyson calls the god of the gaps, except in this case, there isn't even a gap.


Aug 19, 2016
All by itself, with nary a visible helping "hand" at play.
You mean "Hand", right? It's pretty obvious where you're going with this. And, by the way, Antarctic ice core samples prove without a doubt that the world is at least over 800,000 years old, so don't even go there. We didn't see it being made, but we can infer the age of Earth to be probably around 2 billion years old, give or take, from other evidence you might label as heresy.

Aug 20, 2016
@Mark: "could the effect be the one detected?"

Why just that effect? Same "not impossible to exclude, just unlikely."

"except that planet was dislodged by a passing star 70 million years ago."

Different question, and *that* we can exclude. Its ejection must have happened before the current architecture of our solar system happened, driven by Jupiter-Saturn Grand Tack.

"Does Planet Nine really exist, or is it deep space fantasy?"

? That is not the current question of testing its existence.

"the mean number of planets a G2-type star will gain and lose over the course of its first 4.5 billion year."

Another non sequitur.

The question of other system's aggregated effect on our system is currently answered by ~ 10 % comets, forced ~ half the size early on, and ~ 0 % else. Anything more is to be observed in the future, but the prospect looks bleak.

Aug 20, 2016
@Fred: "Please let me know when someone actually publishes the observation with verification that a planetary system has formed somewhere in the universe. All by itself,".

Does the proverbial Dr Johnson kick at the wall: "I verify it thusly."

Our own system, many proplyds, many exoplanet systems observed in various ways. Been in evidence and accepted since the Greeks (Hindus, Chinese, Mayans [IIRC], ...) grokked the solar system as a planetary system. Been published since before science started.

Aug 21, 2016
@TBGL: It is more than a little presumptuous to imply you know the effects of all the close passes over deep time, especially when we don't even know what passed by when. B&B claim to be certain about Planet 9, but even some professional astronomers have expressed doubt as indicated by my provided link. If the observed effect is real, but Planet 9 isn't, how will you explain that? The answer is something else caused the effect or maybe Planet 9 was lost. In that case, either way it seems likely other bodies with significant gravity have played a role.

Aug 21, 2016
@TBGL: It is more than a little presumptuous to imply you know the effects of all the close passes over deep time, especially when we don't even know what passed by when. B&B claim to be certain about Planet 9, but even some professional astronomers have expressed doubt as indicated by my provided link.


Everyone doubts PN until it is verified, it is the null hypothesis.

That doesn't mean it can't be the best explanation for the features seen. I haven't kept up with all the papers, but the initial ones suggested explanations that were inferior, by B&B criticism.

Aug 21, 2016
Wrong way Goldfarb

Aug 22, 2016
"Everyone doubts PN until it is verified, it is the null hypothesis."

This goes beyond a little healthy skepticism. I think it more likely the P9 described by B&B as between 200-1,200 AU and 5-15 Earth masses simply does not currently exist. B&B's actual observations of the elliptical orbits of a small number of objects out there is more persuasive, although not conclusive, that something perturbed their orbits. In short, it does look a little odd. But that fact and a nice simulation does not mean the odds favor the PN described by B&B. He would not be the first whose predictions of large, undiscovered planets in the outer solar system have fallen short.

All that said, we still have wait and see how this actually turns out. Time will tell.

Aug 22, 2016
@TBGL, if you are interested, take a look at this paper: http://arxiv.org/...96v2.pdf

Importantly, their conclusion appears to be the current existence of P9 is possible, but very unlikely.

"This work also suggests that production of the required orbit is somewhat problematic: Capture events can produce the right orbital elements, but the overall cross sections for capture are quite low. Scattering Planet Nine into its current orbit from a smaller initial orbit (within the Solar System) and capturing it from a freely-floating state are also possible, but such events are less likely than ejecting the planet."

Aug 22, 2016

But that fact and a nice simulation does not mean the odds favor the PN described by B&B.


It does, see the B&B paper, it is the best hypothesis. (Or at least better than other they can come up with. That is why they published.)

The paper you then point to is looking for scattering by nearby stars, not the presumed ejection by early migration that happens already in our own system Nice model in a great deal of cases. [ https://en.wikipe...ce_model ] (Consistent with that microlensing sees roughly one giant nomad planet/system ejected.)

If precisely the Nice model Jupiter-Saturn resonance is responsible is another question, that depends on of there really was a late bombardment.

But notably the paper discover that a putative PN would have minute likelihood (<= 3 %) for ejection over the Sun's lifetime.

Aug 22, 2016
"Probabilities for producing the inferred Planet Nine orbit are low (< 5%)." Page 1.

"Planets starting with orbits in the giant planet region of our Solar System have a negligible
chance of scattering into the required orbit. This finding is consistent with previous results
(Adams & Laughlin 2001; Li & Adams 2015), which show that eccentricity and inclination
angles are much more readily altered than semimajor axes during scattering interactions." Page 10.

http://phys.org/n...sun.html

I may be missing something here, but I feel confident the learned authors are well aware of the Nice model. It looks to me like they are saying the odds for "producing the inferred Planet Nine orbit" are 5%, so the odds against are 95%. This amply supports my assertion that B&B are more likely to be wrong than right.

Aug 22, 2016
The two authors of my cited paper appear to be well aware of the Nice model.

http://arxiv.org/...96v2.pdf

Gongjie Li co-authored with Konstantin Batygin a 2014 paper that recited, "Substantial progress has been made toward the characterization of the early dynamical evolution of the solar system through the development of the Nice model."

http://iopscience.../67/meta

Fred C. Adams co-authored a 2013 paper that recited, "At the present time, there are no gross characteristics of the Solar System that are at odds with the Nice model."

https://www-n.oca...XXIV.pdf

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