Two ‘Planet Xs’ May Lurk Unseen Beyond Pluto

Orbits of the remote asteroids 2012 VP113 and a potentially unseen ‘Planet X’ 10 times more massive than Earth that may shape their orbits. Now, some astronomers think there may even be a second large planet orbiting even farther out. Also shown are the Kuiper Belt and Neptune’s orbit. Credit: Scott S. Sheppard/Carnegie Institution for Science with additions by the author

The planets are coming! The planets are coming! Only months after announcing the possibility of a ‘Planet X’ 10 times Earth’s mass orbiting 250 times Earth’s distance from the sun, a team of Spanish astronomers think there may be another massive planet hiding even deeper in the inky depths.

While this artist’s concept shows how the inner solar system would appear from the surface of distant asteroid Sedna. The view from a hypothetical Planet X would be similar. Credit: NASA/ESA/ A. Schaller

In March this year, astronomers reported the discovery of 2012 VP113, an asteroid that orbits farther from the sun than any previously known. 2012 VP113 joins Sedna and a number of other asteroids beyond the outer asteroid belt (Kuiper Belt) whose orbits are aligned in a way that hints at the gravitational influence of a possible planet farther out. Scientists calculate that this world would be about 10 times the mass of Earth and orbit at roughly 250 times Earth’s distance from the sun.

Carlos and Raul de la Fuente Marcos at the Complutense University of Madrid in Spain have taken another look at these distant bodies. As well as confirming their bizarre orbital alignment, the pair found additional puzzling patterns, according to a recent article in New Scientist.

This NASA graphic shows the orbits of Pluto and Neptune. Their paths cross twice every 248 years, but because of the way the orbits are timed, Pluto and Neptune are in no danger of colliding. Credit: NASA

Too small to tug on one another, the team attributes the similarity of their orbits to the ‘shepherding’ influence of a larger unseen body in a pattern called orbital resonance.

We see orbital resonance at play with Neptune and Pluto. The two worlds exert a regular and repeating gravitational attraction on each other causing their orbits to be related by a simple whole number ratio. For every 2 orbits Pluto makes around the sun, Neptune makes 3.

Similarly, 2012 VP113 and friends appear to revolve as a group in lockstep with a distant world with a mass estimated between that of Mars and Uranus and orbiting 200 times Earth’s distance from the sun. Some of these remote asteroids have orbits that take them out to that distance – that’s where a second large planet may play a part.

Since it would be unusual for a distant shepherding planet to orbit so close to its ‘sheep’ unless it too were in resonance with yet another large body, the Spanish team suggests that another ‘Planet X’ 250 times the Earth-sun distance pulls the strings as it were. Their numbers square nicely with the distance predicted in the earlier work on Sedna and 2012 VP113.

For now, 2012 VP113, shown here slowly moving across the sky, is the most distant solar system object seen. It was discovered with the new Dark Energy Camera at the National Optical Astronomy Observatory’s 4-meter (157-inch) telescope in Chile. At closest, it’s 80 times the Earth-sun distance. Credit: Scott Sheppard / Carnegie Institution for Science

Spotting any new Planet Xs will be extremely tricky. The remote asteroids travel along very elongated orbits that periodically take them close enough to the sun for us to photograph them. ‘Close’ is a bit of an exaggeration. Sedna, for example, only pulls up to 76 times the Earth-sun distance at best where it tops out at a feeble magnitude +20.5. Any planets beyond are expected to follow more circular orbits similar to the familiar inner solar system gang and glow ever so faint.

Heat-radiating planets as large as the ones predicted and at the distances suggested, should have been detected by NASA’s WISE space probe’s infrared survey. But WISE’s two complete infrared sweeps of the sky found that no object the size of Saturn or larger exists out to a distance of 10,000 times the Earth-sun distance (10,000 AUs or astronomical units) and no object larger than Jupiter exists out to 26,000 AUs. Still, WISE had its limits. A remote planet colder than about -330 F (-201 C) could escape detection.

Naturally, the results don’t preclude these smaller objects. While hypothetical for the moment, larger telescopes both on Earth and in orbit may one day coax these putative Planet Xs into the light.

For more information on the topic, check out the team’s scientific paper.

20 Responses

  1. caralex

    I’m a bit puzzled by this, Bob. If WISE determined that no planets the size of Saturn or Jupiter exist out to 10,000 AU or 26,000 AU respectively, how did it miss two fairly substantial bodies (if they really DO exist) orbiting at a much closer distance of only 200 and 250 AU?

    1. astrobob

      An Earth-sized planet that was extremely cold – emitted very little infrared light – might not be picked up by WISE. WISE could detect objects only down to about -330 F. Anything colder than that it can’t see. Of course, the researchers might be considered overly optimistic by some.

      1. caralex

        Thanks, Bob. What do you think yourself? Do these planets exist? They’d have to be somewhere between the masses of Earth and Uranus, wouldn’t they?

        1. astrobob

          I can’t say they do or don’t but I’m personally very skeptical. Still I do wonder why the asteroids appeared to be shepherded.

  2. Alan Johnson

    I just found your excellent website today. Open minded, yet technically astute, with a broad range of topics. Sometimes when I think about the large quakes occurring in March, then April over the last several years . . . . I look to the skies and wonder. Your efforts and work are appreciated.


  3. Planet X eh? That takes me back to the early ’70’s when it was the talk of my small circle of budding amateurs. We’d pass those diagrams showing Uranus and Neptune’s orbits being further out compared to where calculations at the time thought they should be. Turns out the calculations were erroneous. When Voyager flew by Neptune in 1989, it allowed a more precise figure of Neptune’s mass and the orbit’s weirdness disappeared.
    Being the fearless one and seeking fame and glory, I’d spend countless hours at the business end of a genuine Tasco P.O.S. 60 mm reflector with the worst alt-azi mount of all times. Needless to say that I came up empty handed. That thing just about made me abandon astronomy but the appearance of comet Kohoutek (C1973 E1) in the pre-dawn hours of december 1973 convinced me to save for some better optics.
    Planet X fever; Catch it 🙂

  4. Barry Warmkessel

    We have orbital parameters with a verified period of an Jovian sized body in a 4969 year orbit about the Sun. Wonder why nobody cares.

    BTW, Here they are compared with Forbes values who almost found it in 1880.
    Table 2 – Vulcan’s Orbital Parameters
    Parameter Value Max. Error Min. 2 Sigma Error Forbes'(1880)
    Period (years) 4969.0 +30.4/- 24.3 +/- 11.5 5000
    Orbital Eccentricity 0.537 +0.088/-0.035 +/- 0.0085 not cal.
    Orbital Inclination 48.44o +3.12o/-9.05o +/- 0.23o 45o
    Longitude of the Ascending Node 189.0o +/- 1.3o +/- 1.3o 185o
    Argument Of Perihelion 257.8o +6.11o/-13.47o +/- 0.90o not cal.
    Time of Aphelion (years) 1970 AD +/- 1.0 +/- 1.0 not cal.
    Table 2

    1. astrobob

      Hi Barry,
      Vulcan – a hypothetical planet between Mercury and the sun – was shown long ago to not exist. As for a Jupiter-sized body in a long orbit, can you point us to discovery observations of this object? As far as I know, there’s no evidence for this either. If it were real, it would be a huge discovery.

      1. George Forbes discovered these two planets in 1880.

        The orbital parameters he found match our Vulcan found years ago. The name Vulcan was given to it years ago by Madam Blavatsky, and she never said it was near the Sun. Would you expect such a body with a 4969 year orbital period to be near the Sun.

        Here is a link that has references to this old work when we thought the orbital period was 5030 years.

        Now modern astronomers are just discovering evidence of this object.

        1. astrobob

          I looked over the material and it smacks of pseudo-science mixed with astrology and a lot of ‘we BELIEVE this to be so’. I’m sorry Barry but I don’t buy it. There’s no direct evidence for “Vulcan” just as there’s no direct evidence yet for any Earth-sized object beyond Neptune. I hope someday we do find another planet out there.

  5. Giorgio Rizzarelli

    Work for the 25-40 meter telescopes so, like E-ELT, if they will able to see them.

    If the two planets X will show to exist, it will be a very fun way for nature to reply to the metropolitan legends about a such planet: “folks you’re wrong about the planet X.. there are two of them”.

    1. astrobob

      No doubt Mike and team are still looking for more remote asteroids. They would love to discover a planet probably more than anyone.

  6. Troy

    This makes me think of how New Horizons has yet to find a Kuiper Belt object to study after the 2016 Pluto flyby. Maybe Pluto did a better job of clearing out its neighborhood than originally thought 😉

  7. Forbes used comet aphelions to find the orbital parameters of his two new planets in 1880, we used an unheard of technique to discover a complete set of orbital parameters for one of these bodies that we think is the heavy element core of an ultra tiny brown dwarf star in 1997. We used ASTROLOGY plus some other scientific data like IRAS data, etc. By using ASTROLOGY, astronomers just push the off button. They just cannot believe that this is a viable technique. It was not until 1999 that we discovered Forbe’s 1880 data in the Stanford library stacks.

    But to verify Forbes or our conclusions, we needed to find a way that was more acceptable to modern scientists. The fact that they matched would just be ignored. Fortunately for us, but not the people of the Earth, the eccentricity of the orbits leads to our Vulcan drawing Kuiper belt objects sometimes into Sun grazing orbits thereby generating comet swarms. These comet swarms are in a 3:2 resonance with Vulcan’s orbit. When the swarms pass thru the inner solar system, a few bodies usually hit Earth. Since we are anticipating Vulcan to be half Jupiter size, these passages are not quite periodic as Vulcan’s mass modifies their period in the outer solar system. However, there is a periodicity we call the RESONATE INTERVAL which is no more than two Vulcan or three sequential comet periods long. It should theoretically be 9938 years. So all we have to do is to look for weather changes induced by the impacts of these bodies on Earth about 9938 years apart. We did and here is what we found.

    Theoretical resonate interval = 9938 years +/- 11 years
    Measured resonate interval between two swarm A, Cluster 1 (A:CL-1) = 9939 years
    Measured resonate interval between two swarm A, Cluster 2 (A:CL-2) = 9951 years
    Measured resonate interval between two swarm B, Cluster 1 (B:CL-1) = 9938 years
    The average of three measured resonate interval values is 9942.7 +/- 5.9 years

    For the astronomers, we can just use CR 105

    and when we put them all together along with Forbe’s result (but with no ASTROLOGY results), we get.
    Thus, the estimated Combined Period = 4970.15 years +/- 8.14 (one sigma) years

    Finding this ultra tiny brown dwarf star’s orbit: a piece of cake.
    Getting astronomers to listen: Nearly impossible

    1. astrobob

      Publish real data – not astrology and theosophy – in a peer-reviewed publication and you will get astronomers to listen. Still looks like mumbo-jumbo to me.

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