A ninth planet?

[PakledHostage]

I don't know if the above video has been posted elsewhere already (it is at least a year old), but I thought I would share it because it puts things into perspective. ANU's rulling out an unknown Neptune sized planet within 350 AU from 90% of the southern sky, doesn't mean much because Dr. Mike Brown's predicted planet 9 is a lot farther out than that.

[Razorforce7]

I thought this was already discovered, this 9th floating sphere is called Nibiru right?

Case closed! I report a mod to close the thread as we have solved this dilemma.

I'm sorry I couldn't get here sooner

[Green Baron]

Hu ? Nope, leave it open, planet 9 is postulated, not discovered as in a telescope. And until then it doesn't have an official name. Naming it would traditionally be the task of the discoverers and if they were consistent it would be from roman or greek mythology.

 

Edited April 3, 2017 by Green Baron

[sevenperforce]

10 minutes ago, Green Baron said:

Hu ? Nope, leave it open, planet 9 is postulated, not discovered as in a telescope. And until then it doesn't have an official name.

 

Sarcasm level: missed.

[Green Baron]

Just now, sevenperforce said:

Sarcasm level: missed.

Oops ... :-)

[IceGiant]

Green Baron does have a point though.  The way the media cover Planet Nine makes it seem like there's scientific consensus when there is anything but.  There are only two guys that are really convinced, and they are masters of shameless self-promotion; plus a bunch of hangers on who enjoy the research money that comes along with it.  But watch the news and you can be forgiven for thinking that this is a sure thing that's only awaiting a photo to officially confirm it.

Edit: I don't want to imply I'm saying that Planet Nine doesn't exist, just that Brown and Batygin's hypothesis isn't proof.  It's not far removed from the calculations that postulated the existence of Vulcan inside Mercury's orbit, or Planet X outside Neptune's.  My gut tells me the odds are closer to 50% than 90%.

Edited April 3, 2017 by IceGiant

[Green Baron]

On 19.2.2017 at 1:58 PM, Green Baron said:

 

The planet nine thing is no bogus. Many people are working on it and a a lot of serious papers have been written about it. Up to now it has been postulated as a perturber in the outer solar system that might well be responsible for the otherwise unexplained orbits of dwarf planets in the kuiper belt and could explains other observations as well. Direct observation is difficult, maybe impossible with current generation telescopes because it is very far out (100s of AUs with an orbital period of ~20.000 years). Mass and orbital parameters have been estimated. It is, probably, only a question of time until it gets "discovered".

 

Expressing a severe doubt was not my intention (quoting myself 'cause too lazy ... :-)). I really didn't get the sarcasm/irony in @Razorforce7's post , that's all. From the papers that i read about it (and i definitely mean reviewed scientific papers) it might well be that it is a question of time and equipment since until the discovery. It just explains a lot of things too well to be done away with.

Edited April 3, 2017 by Green Baron

[Guest]

On 1/20/2016 at 0:29 PM, fredinno said:

If it's larger than Mercury or Mars, the definition of dwarf planet is likely to be redefined... Again.

Yes but then ceres and Pluto would be considered planets right?

[sevenperforce]

24 minutes ago, Leftykap said:

Yes but then ceres and Pluto would be considered planets right?

Not necessarily. Dwarf planet has nothing to do with size. Based on the planetary discriminant equation, Mercury would be considered a "dwarf planet" if it was further from the sun.

Officially, the current definition of "non-dwarf planet" is "gravitationally rounded body that dominates its orbit". But the planetary discriminant equation, which predicts whether a given body will eventually dominate its orbit, depends on the mass and the distance from the star. So even Earth could be considered a dwarf planet if it was far enough away, even if it did in fact dominate its orbit.

[cantab]

The way I see it is simple: We've not found a ninth planet, we've found a good reason to look.

[Green Baron]

Looking forward to the new explanations and models of how solar systems form.

 

Until a few years ago we had the solar system with the rocky potatoes inside and the gas bubbles outside. The model was clear and comprehensible via the forming from a planetary disc, solar winds/radiation pressure, these things.

With current generation telescopes since the 20xx, adaptive and active optics more and more special cases are discovered, rocks far outside from their suns, gas giants skimming the atmospheres of their sun, "rogue" (what a word) planets, "perturbers" (makes me think of a rebel, like in the Corsican flag), multi-star systems ... the first impression is that our system probably is not the typical blueprint of what happens around stars.

 

[Yobobhi]

Well we still have pluto

[Rakaydos]

On 4/3/2017 at 2:53 PM, Green Baron said:

Looking forward to the new explanations and models of how solar systems form.

 

Until a few years ago we had the solar system with the rocky potatoes inside and the gas bubbles outside. The model was clear and comprehensible via the forming from a planetary disc, solar winds/radiation pressure, these things.

With current generation telescopes since the 20xx, adaptive and active optics more and more special cases are discovered, rocks far outside from their suns, gas giants skimming the atmospheres of their sun, "rogue" (what a word) planets, "perturbers" (makes me think of a rebel, like in the Corsican flag), multi-star systems ... the first impression is that our system probably is not the typical blueprint of what happens around stars.

 

There's been a model floating around for years that says that the solar system formed with an extra planet between jupiter and saturn, and that the orbits were unstable and kicked this extra planet out of the solar system. This model predicts the planets current orbits far better than a straight 8 planet simulation, which give something like a 90% chance of kicking saturn out of the solar system.

One of the factors being protoplanetary disk drag, pushing towards circularizing orbits, I wonder if planet 9 could be that ejected (recaptured?) gas giant.

[MaryM]

I'm very happy that our scientists work for our future to make new discoveries but there is really nothing yet known for sure that  proves its existence. I watched this video http://www.bbc.com/news/av/science-environment-35374281/is-there-a-ninth-planet-in-our-solar-system and it helped me to find the answers)

[munlander1]

So to confirm the existence of planet 9, what evidence would be needed?

[vger]

On 4/3/2017 at 11:54 AM, IceGiant said:

Green Baron does have a point though.  The way the media cover Planet Nine makes it seem like there's scientific consensus when there is anything but.  There are only two guys that are really convinced, and they are masters of shameless self-promotion; plus a bunch of hangers on who enjoy the research money that comes along with it.  But watch the news and you can be forgiven for thinking that this is a sure thing that's only awaiting a photo to officially confirm it.

Edit: I don't want to imply I'm saying that Planet Nine doesn't exist, just that Brown and Batygin's hypothesis isn't proof.  It's not far removed from the calculations that postulated the existence of Vulcan inside Mercury's orbit, or Planet X outside Neptune's.  My gut tells me the odds are closer to 50% than 90%.

Isn't at least a done deal that there is SOMETHING messing with the orbits of our planets (ever-so-slightly) that hasn't been unaccounted for?

I'm also waiting for someone to figure out why Pluto is so erratic. I rather doubt a collision with another kuiper belt object of similar size was enough to cause that.

[Green Baron]

A portrait would be best. I shortly heard of other kbos orbits that fit well in the predictions. 

[sjbuggs]

29 minutes ago, vger said:

Isn't at least a done deal that there is SOMETHING messing with the orbits of our planets (ever-so-slightly) that hasn't been unaccounted for?

I'm also waiting for someone to figure out why Pluto is so erratic. I rather doubt a collision with another kuiper belt object of similar size was enough to cause that.

Eris is bigger and further out than Pluto but has an orbit tilted 44d to Pluto's 17.  That would presumably be even harder to explain from a collision. 

My money though is a close pass from another larger object...  the hypothetical companion star (article today about that actually) Sol may have started with, the hypothetical 9th planet way out there or a passing extra-solar object.

 

 

[Starman4308]

2 hours ago, munlander1 said:

So to confirm the existence of planet 9, what evidence would be needed?

Essentially: a photo. Most likely two photos, showing planet X moving against the stellar background.

I continue to insist that this means "tenth planet". Despite the evidence showing that Pluto does not fit the IAU's definition of a planet, dangit, I grew up with Pluto as our ninth planet.

My very excellent mother just served us nine pancakes forever.

[kerbiloid]

Why should we think out a name for the 9th planet?
When they discover us, we can just ask them what's the name of their planet.

[-Velocity-]

5 hours ago, Starman4308 said:

Essentially: a photo. Most likely two photos, showing planet X moving against the stellar background.

I continue to insist that this means "tenth planet". Despite the evidence showing that Pluto does not fit the IAU's definition of a planet, dangit, I grew up with Pluto as our ninth planet.

My very excellent mother just served us nine pancakes forever.

You can't have Pluto be a planet and not have Eris be a planet too.  You'd probably also need to add Makemake, Haumea, 2007 OR10, etc. etc. etc.  Hell, let's just make everything a planet.  Seriously though, it's much better to not show any favoritism to Pluto, people should learn about the Kuiper belt, not just specifically Pluto.  When I was in school, they taught us about Pluto being a planet as well, despite the fact that it was starting to get very clear by that time that it was just a large KBO.  When I told the teacher that Pluto wasn't a planet, it was just a large Kuiper belt object, she just looked at me funny (she wanted the know-it-all to shut up, I bet).  None of the other kids (or the teacher) ever knew what the Kuiper belt was.  They learned about Pluto instead, which misrepresented what we knew about the solar system at that time.

One of the jobs of scientists is sometimes to simplify information for public consumption.  So in that vein, they either have to demote Pluto or make a lot more planets, planets that would far less deserving than the big 8 AND which are smaller than the Moon.  By demoting Pluto, perhaps they can force educators to teach people about the Kuiper belt instead, while keeping the crudely simplistic solar system (of only 8 planets) still memorizable by 2nd graders.  If Pluto hadn't been demoted, "educators" would STILL be ignoring the Kuiper belt and teaching that Pluto is somehow on equal terms with the other planets.  

Yes, the IAU's definition of "planet" sucks, but that doesn't change the fact that demoting Pluto was the right thing to do.  Personally, I think a mass-based definition makes a lot more sense (you have to draw the line somewhere, and mass is the single most important property of any astronomical body).

I'm pretty sure the case for a true planet 9 is coming together very strongly.  Didn't they discover yet more Kuiper belt objects with the same perturbed orbits, and we still haven't been able to find a KBO in an orbit that would rule out planet 9?  If so, that's pretty dang compelling.

6 hours ago, sjbuggs said:

Eris is bigger and further out than Pluto but has an orbit tilted 44d to Pluto's 17.  That would presumably be even harder to explain from a collision. 

My money though is a close pass from another larger object...  the hypothetical companion star (article today about that actually) Sol may have started with, the hypothetical 9th planet way out there or a passing extra-solar object.

 

 

You can't get the observed distribution of orbits from a passing extrasolar object.

Edited June 16, 2017 by -Velocity-

[sjbuggs]

4 minutes ago, -Velocity- said:

You can't get the observed distribution of orbits from a passing extrasolar object.

Good to know...

Quote

 

You can't have Pluto be a planet and not have Eris be a planet too.  You'd probably also need to add Makemake, Haumea, 2007 OR10, etc. etc. etc.  Hell, let's just make everything a planet.

 

I actually am partial to the comment someone made (can't recall who but guessing Phil Plait or NDG) that basically was along the lines that Pluto still is a planet.  Just a Dwarf one.

Quote

You can't have Pluto be a planet and not have Eris be a planet too.  You'd probably also need to add Makemake, Haumea, 2007 OR10, etc. etc. etc.  Hell, let's just make everythin

Still no love for Charon though.  I don't really get the definition of a moon if it's still considered one.  The barycenter lying between the two objects seems like as good as a cut off point as any.  So that should make Pluto-Charon a binary dwarf planet system IMHO.

 

[-Velocity-]

20 minutes ago, sjbuggs said:

Good to know...

I actually am partial to the comment someone made (can't recall who but guessing Phil Plait or NDG) that basically was along the lines that Pluto still is a planet.  Just a Dwarf one.

Still no love for Charon though.  I don't really get the definition of a moon if it's still considered one.  The barycenter lying between the two objects seems like as good as a cut off point as any.  So that should make Pluto-Charon a binary dwarf planet system IMHO.

 

Agreed, it's a binary dwarf planet.  I don't know if the barycenter lying between the two objects is a good cutoff.  It ignores density.  Imagine if an Earth-mass planet orbiting a mini gas giant of like, 10 Earth masses versus if the same object orbited a rocky super-Earth of 10 Earth masses.  The smaller Earth mass planet could be a "moon" around the mini gas giant but a "planet" around the super-Earth, simply because the mini gas giant is more puffed out and has a lower density, therefore allowing the barycenter to fall within the gas giant.  To me, that makes no sense.  Just like I favor defining the boundary between "planet" and not planet by using a simple, arbitrary mass limit (10^23 kg is good), we should define moon/double planet based on the mass ratios.  For example, since Charon is more than 10% of the mass of Pluto, then the system should be considered a double dwarf planet system.  I don't know that 10% is a good number to use, whatever number we pick though is going to be essentially arbitrary.

Also, the Earth-moon system would become a double planet eventually by the barycenter definition, even though it is not one today, because the Moon is slowly stealing rotational energy from the Earth and using it to increase its orbital radius.  But if, again, we just use the SIMPLEST and EASIEST criterion there is, mass, then the Earth-moon system will always be a planet with a moon, because the mass ratio will never change.  But, I guess what seems like common sense to me does not seem like common sense to others.

Edited June 16, 2017 by -Velocity-

[kerbiloid]

Ganymede and Titan can't understand why so much noise about that tiny homeless trash.

Of course their barycenters lie inside their gas giants, but themselves are bigger thatn those "planets/non-planets". 
Strange to call "double planet" Pluto+Charon but ignore double (by their practical significance) planets Jupiter-Ganymede and Saturn-Titan.

Is Duke of Titan lesser than King of Pluto?

Edited June 16, 2017 by kerbiloid

[Green Baron]

Since most are bashing the IAU and it's trespass against Pluto's state among the family of solar system objects i state that i find the definition of planet and dwarf planet comprehensive, clear and constructive.

Until it is changed again, of course, because of new insights in the forming of solar systems.

I am missing a definition of moon, since the discussion about the moon's orbit in another thread ...

 

4 minutes ago, kerbiloid said:

Is Duke of Titan lesser than King of Pluto?

Yes, a duke is lesser than a king ... :-)