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New evidence in support of the Planet Nine hypothesis

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Last year, the existence of an unknown planet in our solar system was announced. However, this hypothesis was subsequently called into question as biases in the observational data were detected. Now Spanish astronomers have used a novel technique to analyse the orbits of the so-called extreme trans-Neptunian objects and, once again, they point out that there is something perturbing them: a planet located at a distance between 300 to 400 times the Earth-Sun separation.

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Solar System
Planet Nine
trans-Neptunian objects

Enrique Sacristán | | July 11 2017 10:21

<p>Will another planet be added to the list of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune in our solar system? / NASA</p>

Will another planet be added to the list of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune in our solar system? / NASA

Scientists continue to argue about the existence of a ninth planet within our solar system. At the beginning of 2016, researchers from the California Institute of Technology (Caltech, USA) announced that they had evidence of the existence of this object, located at an average distance of 700 AU or astronomical units (700 times the Earth-Sun separation) and with a mass ten times that of the Earth. Their calculations were motivated by the peculiar distribution of the orbits found for  the trans-Neptunian objects (TNO) of the Kuiper belt, which apparently revealed the presence of a Planet Nine or X in the confines of the solar system.

However, scientists from the Canadian-French-Hawaiian project OSSOS detected biases in their own observations of the orbits of the TNOs, which had been systematically directed towards the same regions of the sky, and considered that other groups, including the Caltech group, may be experiencing the same issues. According to these scientists, it is not necessary to propose the existence of a massive perturber (a Planet Nine) to explain these observations, as these are compatible with a random distribution of orbits.

A planet is actively interacting with ETNOs in a range of distances from 300 to 400 AU

Now, however, two astronomers from the Complutense University of Madrid have applied a new technique, less exposed to observational bias, to study a special type of trans-Neptunian objects: the extreme ones (ETNOs, located at average distances greater than 150 AU and that never cross Neptune's orbit). For the first time, the distances from their nodes to the Sun have been analysed, and the results, published in the journal ‘MNRAS: Letters, once again indicate that there is a planet beyond Pluto.

The nodes are the two points at which the orbit of an ETNO, or any other celestial body, crosses the plane of the solar system. These are the precise points where the probability of interacting with other objects is the largest, and therefore, at these points, the ETNOs may experience a drastic change in their orbits or even a collision.

Like the comets that interact with Jupiter

“If there is nothing to perturb them, the nodes of these extreme trans-Neptunian objects should be uniformly distributed, as there is nothing for them to avoid, but if there are one or more perturbers, two situations may arise,” explains Carlos de la Fuente Marcos, one of the authors, to SINC. “One possibility is that the ETNOs are stable, and in this case they would tend to have their nodes away from the path of possible perturbers, he adds, but if they are unstable they would behave as the comets that interact with Jupiter do, that is tending to have one of the nodes close to the orbit of the hypothetical perturber”.

Using calculations and data mining, the Spanish astronomers have found that the nodes of the 28 ETNOs analysed (and the 24 extreme Centaurs with average distances from the Sun of more than 150 AU) are clustered in certain ranges of distances from the Sun; furthermore, they have found a correlation, where none should exist, between the positions of the nodes and the inclination, one of the parameters which defines the orientation of the orbits of these icy objects in space.

“Assuming that the ETNOs are dynamically similar to the comets that interact with Jupiter, we interpret these results as signs of the presence of a planet that is actively interacting with them in a range of distances from 300 to 400 AU,” says De la Fuente Marcos, who emphasizes: “We believe that what we are seeing here cannot be attributed to the presence of observational bias”.

“We believe that what we are seeing here cannot be attributed to the presence of observational bias”, the authors say

Until now, studies that challenged the existence of Planet Nine using the data available for these trans-Neptunian objects argued that there had been systematic errors linked to the orientations of the orbits (defined by three angles), due to the way in which the observations had been made. Nevertheless, the nodal distances mainly depend on the size and shape of the orbit, parameters which are relatively free of observational bias.

“It is the first time that the nodes have been used to try to understand the dynamics of the ETNOs”, the co-author points out, as he admits that discovering more ETNOs (at the moment, only 28 are known) would permit the proposed scenario to be confirmed and subsequently constrain the orbit of the unknown planet via the analysis of the distribution of the nodes.

The authors note that their study supports the existence of a planetary object within the range of parameters considered both in the Planet Nine hypothesis of Mike Brown and Konstantin Batygin from Caltech, and in the original one proposed in 2014 by Scott Sheppard from the Carnegie Institute and Chadwick Trujillo from the University of North Arizona; in addition to following the lines of their own earlier  studies (the latest led by the Instituto de Astrofísica de Canarias), which suggested that there is more than one unknown planet in our solar system.

Is there also a Planet Ten?

De la Fuente Marcos explains that the hypothetical Planet Nine suggested in this study has nothing to do with another possible planet or planetoid situated much closer to us, and hinted at by other recent findings. Also applying data mining to the orbits of the TNOs of the Kuiper Belt, astronomers Kathryn Volk and Renu Malhotra from the University of Arizona (USA) have found that the plane on which these objects orbit the Sun is slightly warped, a fact that could be explained if there is a perturber of the size of Mars at 60 AU from the Sun.

“Given the current definition of planet, this other mysterious object may not be a true planet, even if it has a size similar to that of the Earth, as it could be surrounded by huge asteroids or dwarf planets,” explains the Spanish astronomer, who goes on to say: “In any case, we are convinced that Volk and Malhotra's work has found solid evidence of the presence of a massive body beyond the so-called Kuiper Cliff, the furthest point of the trans-Neptunian belt, at some 50 AU from the Sun, and we hope to be able to present soon a new work which also supports its existence”.


C. de la Fuente Marcos, R. de la Fuente Marcos. “Evidence for a possible bimodal distribution of the nodal distances of the extreme trans-Neptunian objects: avoiding a trans-Plutonian planet or just plain bias?”. Monthly Notices of the Royal Astronomical Society: Letters, julio de 2017. DOI: 10.1093/mnrasl/slx106. (Preprint disponible en

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Geographical area: International
Source: SINC


  • (50) Barry Warmkessel |Thursday 13 July 2017 10:34:41 am

    We have the nominal mass and orbit parameters of a Jovian planet we have dubbed Vulcan with a semi-major axis of 291 AU, perihelion of 134.8 AU, and aphelion of 447.6 AU. It has the same orbital inclination as one of the two proposed for Planet Nine. Details here:
    A Dangerous New Jovian Sized Body In Our Solar System
    Beyond a reasonable doubt, the ancients were aware of an additional Jupiter like body in our solar system, one that most of our current astronomical community is totally unaware of. However, some powerful members of this community were aware of this ancient knowledge and appears to have combined it with intelligence gained from extra-terrestrial aliens contacts. Apparently, there may be an ultra-tiny brown dwarf in our outer solar system. The Pioneer, Voyager, IRAS satellite and possibly even the Hubble space telescope were constructed to find and observe this half Jupiter sized brown dwarf star.

    While there is no proof that others have ever found this solar body, this web site has been able to deduce it's mass and orbital parameters. Moreover, many of these values have been verified beyond a reasonable doubt. This body has been dubbed Vulcan because a theosophist, Madam Blavatsky, already named it that and described how it affects the formation of mankind's great avatars.

    Physically, however, Vulcan's orbit is such that it draws small bodies from the Kuiper Belt, and casts them into comet like orbits. Sometimes these objects pass through the solar system in Sun grazing orbits. Then they break up forming meteor or comet swarms. At least five such swarms have been identified. Often, some members of these swarms impact Earth when they pass through the inner solar system. More than thirty such impacts causing massive weather changes have been identified from tree ring and ice core data spanning the past 15,000 years.

  • (50) P Edward Murray |Thursday 13 July 2017 10:35:19 am

    We already have a 9th Planet and it IS Pluto. Such a hypothetical new Planet would be a 10th and another the 11th. Not to mention the other "Dwarf Planets" Planetary Scientists call the dwarf planets "Planets" And the new IAU definition is, in many ways , irrelevant because by their definition our own Earth isn't even a planet!

  • (50) Kenneth Boyd |Friday 14 July 2017 9:06:17 am

    The ninth planet is still Pluto , no matter what DeGrasse says !

  • (50) radamantic |Friday 14 July 2017 1:36:05 pm

    Not said by DeGrasse, but by IAU: main international astronomical authority.
    Single opinion is null.

  • (50) Miguel Montes |Sunday 16 July 2017 9:37:47 pm

    P Edward Murray said: " And the new IAU definition is, in many ways , irrelevant because by their definition our own Earth isn't even a planet!"

    You don't understand the definition of planet. You're probably putting into the question the "cleaning the orbital neighborhood" bit of the definition. The IAU definition, yes, needs a bit more clarification because it's not clear, but that "cleaning the orbital neighborhood" concerns OBJECTS OF THAT SAME SIZE [or bigger].

    The Moon is not the same size as the Earth. There's no other object, in Earth's orbital neighborhood, with the size of the Earth. Only the Earth. Therefore, the Earth is a planet.

    Pluto fails this point. It crosses to the interior of Neptune's orbit. Neptune is BIGGER than Pluto. Therefore, Pluto hasn't cleaned up its orbital neighborhood of objects of the same size (or bigger) - Neptune's there, remember? So, Pluto isn't a planet.


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