2 new planets in solar system?

[Melakon]

Although Pluto hasn't regained its former status, some astronomers think there may be more beyond it. Note that the article says there is no direct evidence to support their theory.

http://www.msn.com/en-us/news/techn...stem-say-astronomers/ar-AA8lmCV?ocid=oie8dlpg

Two more planets in our Solar System, say astronomers

The Solar System has at least two more planets waiting to be discovered beyond the orbit of Pluto, Spanish and British astronomers say. The official list of planets in our star system runs to eight, with gas giant Neptune the outermost. Beyond Neptune, Pluto was relegated to the status of "dwarf planet" by the International Astronomical Union in 2006, although it is still championed by some as the most distant planet from the Sun.

In a study published in the latest issue of the British journal Monthly Notices of the Royal Astronomical Society, researchers propose that "at least two" planets lie beyond Pluto. Their calculations are based on the unusual orbital behaviour of very distant space rocks called extreme trans-Neptunian objects, or ETNOs.

In theory, ETNOs should be dispersed in a band some 150 Astronomical Units (AU) from the Sun. An AU, a measurement of Solar System distance, is the span between Earth and the Sun -- nearly 150 million kilometres (almost 93 million miles). ETNOs should also be more or less on the same orbital plane as the Solar System planets. But observations of about a dozen ETNOs have suggested a quite different picture, the study says.

If correct, they imply that ETNOs are scattered much more widely, at between 150 and 525 AU, and with an orbital inclination of about 20 degrees.
To explain this anomaly, the study suggests some very large objects -- planets -- must be in the neighbourhood and their gravitational force is bossing the much smaller ETNOs around.

"This excess of objects with unexpected orbital parameters makes us believe that some invisible forces are altering the distribution" of the ETNOs, said Carlos de la Fuente Marcos of the Complutense University of Madrid.

"The exact number is uncertain, given that the data we have is limited, but our calculations suggest that there are at least two planets, and probably more, within the confines of our Solar System," the Spanish scientific news agency Sinc quoted him as saying.
"If it is confirmed, our results may be truly revolutionary for astronomy."

So far, there is no direct evidence to substantiate the theory.

Marcos's team, which includes astrophysicists at the University of Cambridge, devised a model based on changes previously observed in the orbit of a comet called 96P/Machholz 1 when it came near Jupiter, the biggest planet in the Solar System. Based on this model, the movement of the ETNOs was consistent with one planet at nearly 200 AU and another at about 250 AU, they said. Last year, the ALMA advanced telescope, located in Chile's bone-dry Atacama desert, found that planets in other star systems can form hundreds of AU from their sun.

Neptune orbits at an average distance of about 30 AU, and Pluto, which has a highly eccentric orbit, circles the Sun at an average of about 40 AU.

 

[YellowSubmarine]

Those wouldn't be planets, but dwarf planets. They would be too far out to be planets. Confusing, isn't it?

I like that. I support the planets. Not completely implausible, the study doesn't make it that much more plausible, but at least it's something.

 

[Kobayshi Maru]

I believe I read an article about that but they weren't sure yet.

These planets must be frozen solid even if their surface is a mix of helium and hydrogen.

 

[MacLeod]

Haven't we been talking about the possibility of PLanet X for decades? If one or more does exist, they may be very hard to detect.

 

[Alidar Jarok]

Those wouldn't be planets, but dwarf planets. They would be too far out to be planets. Confusing, isn't it?

I don't see anything in the article suggesting whether they have or have not cleared their own orbit. Distance, of course, isn't determinative of whether it's a full planet or dwarf planet. Ceres is a dwarf planet and it's between Mars and Jupiter.

 

[Christopher]

Those wouldn't be planets, but dwarf planets. They would be too far out to be planets. Confusing, isn't it?

Sorry, this is wrong. Here's a more detailed article that states it more clearly:

http://www.universetoday.com/118252...t-two-more-large-planets-in-the-solar-system/

First off, they're not proposing mere dwarf planets; that wouldn't be news at all, since we already know about plenty of potential or confirmed dwarf planets beyond Pluto. In fact, if they exist, they're larger than Earth:

“This property appears to be shared by almost all known asteroids with semimajor axis greater than 150 au and perihelion greater than 30 au (the extreme trans-Neptunian objects or ETNOs), and this fact has been interpreted as evidence for the existence of a super-Earth at 250 au. In this scenario, a population of stable asteroids may be shepherded by a distant, undiscovered planet larger than the Earth that keeps the value of their argument of perihelion librating around 0° as a result of the Kozai mechanism.”

And second, it is possible for planets to form that far out:

Of course, the theory put forth in two papers published by the team goes against the predictions of current models on the formation of the Solar System, which state that there are no other planets moving in circular orbits beyond Neptune.


But the team pointed to the recent discovery of a planet-forming disk around the star HL Tauri that lies more than 100 astronomical units from the star. HL Tauri is more massive and younger than our Sun and the discovery suggests that planets can form several hundred astronomical units away from the center of the system.

 

[Nerys Myk]

Haven't we been talking about the possibility of PLanet X for decades? If one or more does exist, they may be very hard to detect.

Planet 10? Better call Buckaroo Banzai

 

[YellowSubmarine]

I don't see anything in the article suggesting whether they have or have not cleared their own orbit. Distance, of course, isn't determinative of whether it's a full planet or dwarf planet. Ceres is a dwarf planet and it's between Mars and Jupiter.

No, but they don't really say the opposite either. And I think they need to, because Earth is so small that I have my doubts it can still clear its orbit at that distance. Bossing a few objects around is not necessarily "clearing". The orbital periods would be huge, the distances enormous, and Earth's gravitational field wouldn't be strong enough to take care of all the little annoying rocks in its way.

I am thinking about Pluto. Neptune is a planet because it is big enough to win orbital resonance with Pluto – and if it didn't Pluto would be in its orbital way constantly, though not for long. There's very high chance of dwarf planets and other objects crossing the orbits of these new Earths like they do Neptune, and unless they most have been bossed into resonant orbits, these Earths are not exactly planets. It would take much more time for an Earth to alter the orbit of an object to be out of its way than a Neptune.

 

[Christopher]

The whole "clears its orbit" thing is a problematical part of the definition, because technically planets like Earth and Jupiter haven't fully cleared their orbits, because they have Trojan asteroids. And it hardly seems relevant here. If we're talking about objects larger than Earth, it would be silly not to call them planets. I think the orbit-clearing parameter is only meant to be a way to clear up the ambiguity for a smaller object that's on the borderline between dwarf and full planet.

Really, out there in trans-Neptunian space, I don't think anything could really have cleared its orbit. Here in the inner/middle system, most of the asteroids and debris were cleared out by Jupiter's gravity billions of years ago. Out there, it's enormously more cluttered with comets and such. I think that any further Jupiter-sized planets that far out have been ruled out. So there's just too much stuff out there for the orbit-clearing parameter to be applicable.

 

[tomswift2002]

Haven't we been talking about the possibility of PLanet X for decades? If one or more does exist, they may be very hard to detect.

I remember hearing about another planet back in the 90's (Dyonius? If I remember). But back then I remember it was theorized that the planet was in an orbit that was very different from all the other planets, including Pluto. I remember the orbit was compared to a North-South orbit, whereas Earth, Mercury and the other planets were compared to an East-West orbit, while Pluto was doing a South-West to North-East type orbit.

 

[Takeru]

Haven't we been talking about the possibility of PLanet X for decades?

Yes, I remember ALF doing an episode about that, he made Brian add the planets Dave and Alvin to his model of the solar system and Willi mentioned the possibilities of other planets but that there was no proof.

 

[Kobayshi Maru]

For all we know there could be a dozen of planets out there but if they are at the very edge of the solar system, they reflect very little light and move extremely slowly, so it's hard to make them out, if not impossible.

 

[YellowSubmarine]

The whole "clears its orbit" thing is a problematical part of the definition, because technically planets like Earth and Jupiter haven't fully cleared their orbits, because they have Trojan asteroids.

The Trojan asteroids don't leave the Lagrangian points, i.e. they always move away as Jupiter approaches. Hence, you can say they have been cleared out of its orbit – they don't stand in its way. That said, I prefer gravitationally dominant. Or really, "bossing everyone in its orbit". It is a phrase made for Jupiter.

 

[Kobayshi Maru]

The whole "clears its orbit" thing is a problematical part of the definition, because technically planets like Earth and Jupiter haven't fully cleared their orbits, because they have Trojan asteroids.

The Trojan asteroids don't leave the Lagrangian points, i.e. they always move away as Jupiter approaches. Hence, you can say they have been cleared out of its orbit – they don't stand in its way. That said, I prefer gravitationally dominant. Or really, "bossing everyone in its orbit". It is a phrase made for Jupiter.

More precisely they form an equilateral triangle with Jupiter and the sun and that means they may not even be in Jupiter's orbit, especially if that orbit is elliptic with a great difference between it's nadir and it's zenith.

 

[Christopher]

The point remains, it's a nonissue, because nobody is seriously going to suggest that an object bigger than Earth is not a planet, no matter what else is in its orbit.

 

[YellowSubmarine]

Yes. But that would be almost as arbitrary as planets were before we had a definition.

 

[Kobayshi Maru]

Yes. But that would be almost as arbitrary as planets were before we had a definition.

Size is not everything...

 

[Mudd]

They can get in line behind Pluto.

 

[YellowSubmarine]

As long as they don't form equilateral triangles we will be safe.

 

[Kobayshi Maru]

They can get in line behind Pluto.

At least Pluto will no longer be the only one in its category.