Where is Planet Nine?

The orbit of Planet Nine

While Planet 9 has not yet been seen, its existence has been revealed by the gravitational effects that it has on the most distant objects known in the solar system. We have used a combination of computer simulations and observations of distant objects to make a preliminary estimate of the current orbit of Planet Nine. This analysis is all detailed in a new scientific paper that we are preparing, but we would like to share the basic results so that everyone will know where and how to try to track down Planet Nine in the sky.  As we are still finalizing the results, don't be surprised if things change a little in the final scientific publication; do be surprised if they change a lot, though.

Here is what we have inferred to date:
  • Planet Nine has an orbit which is anti-aligned with respect to the 6 most distant eccentric Kuiper belt objects, so it must come to perihelion (its closest approach to the sun) at around a Right Ascension in the sky of 16 hours, which means that the perihelion position is straight overhead in late May. Conversely, the orbit comes to aphelion (the furthest point from the sun) at about 4 hours, or straight overhead in late November.
  • The alignment of distant Kuiper belt objects is best explaned if the perihelion distance is approximately 200 AU (one AU is the distance from the Earth to the Sun. Neptune is 30 AU from the sun), though it could be as distant as ~350U. The apphelion is harder to pin down (since Planet Nine is so far away that little happens when it is out there) but it is between about 500 AU and 1200 AU. We actually have a tighter set of constraints, but this gives a good approximation.
  • To cause the effects that we see, the mass of Planet Nine must be about 10 times the mass of the Earth. It is possible that a mass as low as 5 Earth masses will work. It is also possible that it could be higher. More computer simulations are required to answer these questions. Such an object seems likely to be an ejected ice giant core, thus we assume that the size of Planet Nine is between about 2 times the radius of the Earth and 4 times the radius of the Earth, in keeping with observations of exoplanets of similar mass. We further assume that Planet Nine looks like Neptune and has a similar albedo.
  • The computer simulations show us that the plane of the orbit of Planet Nine is approximately the same as that of the six aligned distant Kuiper belt objects (which are, themselves, all in approximately the same plane)
From those inferences, we can estimate the orbital path of Planet Nine, the distance away, how bright is is, and how fast it is moving in the sky. We can summarize our findings in this simple plot, which we refer to as the treasure map:

 The top plot shows our estimated orbital path. The red lines show the approximate outlines of the Milky Way galaxy, which we include in the plot as a warning: it is a lot harder to find objects when the bright Milky Way galaxy is in their background, as we witnessed with all of the difficulties that the New Horizons team had in finding Kuiper belt objects to go to after the Pluto flyby. If Planet Nine happens to be at one of these two places in its orbit it will, unfortunately, be much harder to find. The blue line shows the ecliptic -- the path of the planets across the sky -- which shows you than Planet Nine is tilted by about 30 degrees compared to the other planets of our solar system. The ~20 degree width of the estimated path of Planet Nine is largely due to the uncertainties in inclination and argument of perihelion.

Next is shown the distance to Planet Nine. In this plot you can see the positions in the sky where Planet Nine is at its closest and most distant from the sun. The largest uncertainty is in is furthest distance, which could be as large as ~1200 AU.

Below is an estimate of the magnitude (brightness; larger numbers mean fainter; sorry; blame the ancient Greeks), which is a function of both the distance and the size.

Finally we show the speed that Planet Nine would be moving across the sky at opposition. The speed is almost entirely due to parallax, with a tiny bit of orbital motion to counter the parallactic motion. The units are arcseconds per hour, which is the until that most of us who observe distant objects in the solar system think in. A typical object in the Kuiper belt, for example, moves at something like 3 arcsecond/per. Eris, which is the most distant confirmed object still known in the solar system, moves at a speed of 1.5 arcseconds per hour, which is so slow that it was missed the first time around. Most surveys of the outer solar system would not be able to find Planet Nine, even if it were quite bright, as they would just think it is a stationary star. A few exceptions are noted below.

Observational limits on the presence of Planet Nine 

At its closest approach to the sun, Planet Nine is not particularly faint. Many high end back yard telescopes would have the capability of seeing it. More importantly, many rigorous astronomical surveys would likely already have detected. We think, therefore, that Planet Nine is not at its closest (with the usual caveat that the Milky Way galaxy makes things difficult). The strongest observational limits come, we think, from the following surveys (if you know of another survey that covers the right region of sky to the right cadence, please let us know!):

WISE search for Planet X:

Two years ago, using data from the WISE survey (a thermal infrared wide field all sky survey in space) Kevin Luhman showed that there were no Jupiter or Saturn mass Planet Xs out to a vast distance. Sadly, the survey is not very sensitive to ~Neptune sized objects, which could barely be seen to Planet Nine's ~200 AU closest approach. Luhman has redone the survey using the more sensitive bands of the WISE data (but which covers a very limited part of the sky), and reports that there is still nothing there. He is still trying to understand what the limits are for a ~10 earth mass object, but we have hope that WISE would have seen Planet Nine in the section near Planet Nine's perihelion where it crosses the Milky Way. Stay tuned.

Serendipitous all sky survey: 

A year ago I combined data from he Catalina Sky Surveys, which look for near earth asteroids, to turn it into a powerful search for slowly moving objects. This survey was one of the first (since Tombaugh and Kowal!) to cover a large part of the sky and be sensitive to extremely slowly moving objects (corresponding to distances out to ~10,000 AU). The survey recovered every single one of the bright known Kuiper belt objects (except for those in the plane of the Milky Way galaxy; again), but found no new ones. We estimated 100% efficiency to a magnitude of ~19.1 in the north and ~18.6 in the south. Even this relatively shallow survey eliminates much of Planet Nine phase space.

Pan STARRS transient survey:

A week ago I took the publicly available Pan STARRS transient survey and ran it through the same analysis as I did for the Catalina Sky Survey. I have yet to understand the depth of the survey completely, but it looks like it goes to something like a magnitude of ~21.5. It covers all but the southernmost parts of Planet Nine's orbit. Except for the galactic plane. Argh. But Planet Nine is nowhere to be seen.

Pan STARRS moving object survey:

At the DPS meeting this year, Holman et al. presented a more complete analysis of the complete PS1 data, including one sensitive to very slowly moving objects, and found no Planet Nine (or anything else distant) to a magnitude of approximately 22.5 (Matt is still working on precise numbers).

So where can Planet Nine be?

Putting it all together, we have a crude picture that looks like this of where we can rule out Planet Nine (sorry for the ugliness; today got busy...):



The Catalina, PanSTARRS transient & moving object surveys do a great job of ruling out much of the sky. They generally miss the galactic plane, but that is mostly filled in by WISE, at least at closest approach. Though we can't be 100% sure yet.

The biggest unexplored territory is where, statistically, it is most likely to be: near aphelion. Sadly, aphelion is also very close to the Milky Way galaxy. Ugh.

So where is it? Probably distant. 500 AU+. Probably fainter than 22nd magnitude. Very possibly in the middle of the Milky Way galaxy.

Now go find planet nine.




108 comments:

  1. Will do, I'll report my results back tomorrow!

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  2. AWESOME! We're middle-aged folks planning on getting our first telescope in the spring but we're now moving that date up! Thank, you, thank you!

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    1. As neptune and uranus receive only 40% their amount of sunlight, i would rather think i would be quite difficult to see planet nine. But, good luck! i will try to look for it to, when we know the exact orbital coordinates!

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    2. don't know why it says unknown blogger :(

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    3. You are probably underestimating how hard it would be to see planet nine. (And the mention of "back yard telescopes" in the article isn't helping.)
      Just as a ballpark estimate, given the low bound of apparent magnitude of 20 and assuming good viewing conditions, you might be able to make out planet nine in an astrophoto taken with a consumer-grade DSLR at 10 min exposure through a 14" telescope on a motorized equatorial mount.
      Assuming that you already have a DSLR camera, the telescope would cost somewhere in the neighborhood of 8-10 grand.

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    4. Time to re-focus our Kepler telescope to something in-house, especially since the planet right now is against the milky way backdrop with? (hoping the Kepler telescope can achieve such low angular resolution to see something so closeby!)

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    5. can it pass the earth or hit the earth?

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  3. the planet should be named Prometheus

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    1. It should be named Echo since people have been "echoing"/talking about planet x for years.

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    2. It's as if talks of planet x has been echoing with news of it for a century. Echo, I believe a nymph that fell in love with narcissus was cursed by her a for it believe flirating with Zeus to repeat everything someone says for life. She was lonely since she couldn't respond to anyone and couldn't win narcissus love. If this planet hasn't been found for all this time, it would be as lonely as Echo

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    3. Echo was a nymph that Zeus I believe fell in love with so Herald cursed her to repeat everything someone says. That's why we say echo today. She also cursed her love, narcissus, to fall in love with his reflection. She became lonely for the rest of her life. Planet x/9 would be as lonely as Echo since it's so far out in the solar system.

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    4. One last comment. What I meant by echoing about a planet for years is that people have been talking about new planets for years and it's becoming like a echo that keeps popping up.

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    5. It should be called 'Boosnaastikal'

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    6. can it pass the earth or hit the earth?

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  4. I have relatively extensive experience with the Sloan Digital Sky Survey- especially finding images of TNOs. I will be looking for this object.

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    1. Anyone else think that the SDSS might be a good tool to use?

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  5. Another name would be Enatos which is the greek name for ninth in the series of planets.

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  6. What kind of astronomer forgets to plot magnitudes backwards?

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  7. Please let's use something starting with 'P'! I want the mnemonic "My Very Educated Mother Just Served Us Nine Pizzas" to work again! :)

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    1. It's not a good mnemonic in the 21st century. Nine salads would be better.

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    2. Both Pallas and Athena (Athene) are already in use in the asteroid belt. Nearly all Greek and Roman mythological figures of any significance have been taken, female names are particularly depleted (for quite a while it was traditional to use female names for asteroids). The situation is so bad that some deities correspond to multiple objects with different spellings. E.g. there's an asteroid called Nyx and a moon of Pluto called Nix.
      Since the planet imposes order on Kuiper Belt objects, it would be fitting to go with some aspect of order and stability, such as Aneris, Salus or Sancus. (The most logical choice would be to use Harmonia or Discordia - direct counterparts of Eris - but both names are already taken. Pax is also taken.)

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    3. I think "Prometheus" might still be a good name to use:
      (1) His story is both tragic and bad-ass from the folklore, which our planet here shares a lot
      (2) In NYTimes article it mentions how an encounter with Jupiter/Saturn may have ejected it from the inner system which is parallel to the story of Jupiter(Zeus) punishing Prometheus to a lonely mountain
      (3) The myth has Prometheus tied to a rock with eagles eating his liver and attacking him. For our planet, although not exactly the same, the Kuiper belt objects can be "eagles" picking at the planet and stealing it energy during orbit manoeuvres. Also the cold confines of the outer solar system equates to Prometheus being tied on a cold rock on a lonely mountain!

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    4. Prometheus is taken too - twice:
      https://en.wikipedia.org/wiki/1809_Prometheus
      https://en.wikipedia.org/wiki/Prometheus_%28moon%29

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    5. Just realized that I made a mistake. Discordia is not taken but she's a goddess of chaos (Roman equivalent of Eris). Concordia is a goddess of order and she is taken (https://en.wikipedia.org/wiki/58_Concordia)

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    6. Could sneakily get Pluto back in using "Hades" (Greek form of Pluto)

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    7. The mnemonic "My Very Educated Mother Just Served Us Nine Pizzas" Is perhaps not the ultimate. It confusingly uses the word "nine" for planet eight. And neglects that there are probably ten planets in all. It would be great if the outer three were planets 'N', 'O', and 'P',like the orbits of heavy atoms.
      Perhaps 'Oceanus' (the second sea-god, I believe, following Neptune as first), for planet nine.
      And (if Prometheus is taken)'Proteus' for planet ten - the first to be encountered from outer space.
      Whilst at it, it is time to allot real names for earth, sun and moon. Gaia or Astraea, Sol, and Luna, perhaps.
      John Barton

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    8. Prometheus is twice taken, Proteus is taken, Astraea is taken.
      Have to brag sorry
      I'm 14 and I knew this right off the bat

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    9. Personally, I'm finding it amusing that Planet Nine is currently known as Planet X.

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    10. I've got some ideas, also found some good suggestions on the net:
      -Hyperion (but this name is also a moon of Saturn sadly)
      -Tartarus (prison for the Titans, far below Hades)
      -Aether(us) (Aether is the father of Uranus)
      -Erebus (like Aether and Tartarus a primordial god, the personification of darkness)
      -Yuggoth (step away from greek/roman gods and do something contemporary, Lovecraft's fictional planet; deemed to be located at the very edge of the Solar System)
      -Black star (tribute to Bowie)
      -Nibiru (Babylonian, also could stop all conspiracy theories about this planet, or fuel them, hard to predict)
      -Scotus (latin equivalent to the Greek god Erebus)
      -Plu-two (from reddit commenter, Honorable Mention just because it is funny)

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    11. Beware of , Nibiru , wormwood , nemesis ... The annunaki are coming for are gold! Lock up your necklace's, rings and braclets!!!

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  8. Also this would be a great time to turn our Kelper telescope in-house and search for this planet against the backdrop of Milky Way stars (he said hoping the telescope has low enough angular resolution to do so!)

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    1. You nailed why Promethus should be this celestial body's name. It just fits. Thanks,great job in putting it out there.

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    2. Prometheus is already taken so I think it's unlikely that the Planet will be named prometheus

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    3. Prometheus is already taken so I think it's unlikely that the Planet will be named prometheus

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  9. If it's a Super-Earth and not a Sub-Neptune then it's likely to retain its primordial H2/He atmosphere. If the surface pressure is <300 bar, then it could be an Ocean Planet. Poseidon seems a good choice of name...

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    1. I have a hard time believing that. Basically ALL its energy has to be internally driven. Perihelion, aphelion and planet rotation would have no weather effect to a planet 20 times further away from the Sun than Neptune and takes 10 to 20 thousand years to make one orbit around the Sun. I would expect its thick atmosphere to be essentially un-moving and static; the planet surface cryogenicaly locked with not sublimation occurring. The surface would be all pressure, no heat with not even a breath of a breeze.

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    2. What if Planet 9 has captured a few dwarf-planet-sized moons? Could tidal effects get a little weather going?

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    3. Did you work that out before or after you saw the pictures of Pluto Neil?

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  10. If you wanted to keep with the Inuit theme associated with Sedna, you could call this object "Anguta" (ang-oo-ta), after the father of Sedna — i.e. the one who chopped off her fingers. He's also a psychopomp, i.e. he leads the dead to the underworld, the frozen wasteland of Adlivun ("those below us"), where they remain for a year, undergoing purification before ascending to the Land of the Moon, also known as Quidlivun or Qudlivun ("those above us").

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  11. Hey Mike, I'd like to remind you that I did about 8000 degrees of sky to V~21 looking for this back in 2007. Many of my search areas do overlap your predictions... http://adsabs.harvard.edu/abs/2007AJ....133.1247L

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    1. I wonder if the superblink survey would have spotted it?

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    2. Doy. yah. I'll check out the overlaps!

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  12. Any chance it'll end up being named Tyche after the hypothetical planet people have thought might be there for a while?

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    1. We should give the the planet the Greek importance it deserves. Name telescopes or observatories after observers of the cosmos.How planets are named is more than just looking or searching for them.

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  13. Can you post a skymap w constellations of the approximate swath of Planet 9's orbital path?

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    1. Please...for us folk who don't understand the treasure map.

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  14. I'm the most ignorant person on this subject. But wouldn't it be easier to build a bunch of cheap probes that would be launched towards diffrent sections of the Kepler belt? I'm sure once they start to get far enough out there we would have a better chance of detection.

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    1. Sadly not. Launching probes, and the communications with them, are expensive. If this planet exists, it's likely in the records of previous sky surveys, and going through those is quite cheap.

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  15. Prometheus is used but this is an ideal use of this figure in greek myth. I believe he should be assigned to planet. He is just to important to be just a moon. It is a cool to be connected to the people of earth. THIS WORD ALSO SOUNDS STRONG AS WELL AS EXOTIC>

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  17. A solution to this "already used "argument would be to name the planet Prometheus Prime. It gives the planet the status over the moon.

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  18. Another name might be Promethea. Stick with the theme of cast away and cold. It gave fire to the earth which we might say is the life we enjoy in our goldilocks zone. What a perfect analogy.

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  19. I will call it Rupert, come what may. Too much of an inside joke to be ever considered..

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  20. Are you sure the middle of the Milky Way is the right spot to search? My first preference would be to look where Planet Nine's orbit is away from the ecliptic, in Cetus. But you already searched there and found Sedna. (Although lightning did strike twice for Galilei, who saw Neptune in his telescopes right next to Jupiter and its moons, but didn't recognize it as a planet)

    Following the orbit a bit further towards regions with more stars, I get to the northern part of Orion, where there are more stars and also nebulae and still some distance to the ecliptic. That's where I would search first.

    As for a name, of the names that were already used for other objects I prefer Persephone, especially if it would look different depending on season (if it actually develops a hydrogen ocean in aphelion).

    Of the yet-unused names, I prefer Apate, sister of Eris and Nemesis and goddess of deceit, leading astray so many objects. The ones we can see in those extreme orbits are not sheep being protected as some might think, they are rather survivors that found safe hiding spots from the invader.

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  21. It should be called 'Boosnaastikal'

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  22. I will call it George, and I will hug it and squeeze it.

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    1. Fun fact: When Herschel discovered Uranus, he wanted to name it after then-British king George. Most good names are already taken... but I think "Jehoshaphat" hasn't been used for a planet yet.

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  23. Why is the "clutter" from background stars in the Milky Way a problem? Why couldn't a sophisticated computerized blink microscope eliminate the objects that did not move in two exposures taken far enough apart to show something that DID move? Clyde Tombaugh did this manually (and laboriously) when he discovered Pluto.

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    1. If Planet Nine is out at 1,200au, then it is moving across our sky more slowly than some of those background stars, and a blink comparator will not help in that circumstance.

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    2. At 1200 au from the Sun, the motion would be around 30-40 arcsec per year if I am not wrong, while the fastest star (Barnard's star) moves at about 10 arcsec per year. The movement would therefore still be much larger than for any star.

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    3. You know, Adrien, the team that is making this prediction is cautioning astronomers that, because of its slow movement and dim appearance, Planet 9 could be mistaken for a background star. I read that today, long after having posted what I did above. Some years ago, I did some back of the envelope style calculations regarding a hypothetical Jovian Planet orbiting at 900 AU. My calculations indicated that such a planet would be no brighter than Sedna was in its discovery photographs, and that, in photographs of similar resolution to Sedna's discovery photographs, it would take more than a week to move a single pixel. 1200 AU is significantly more distant from the host star than the 900 AU my calculations were based upon, which would make Planet 9 much dimmer and more slowly moving than the planet I was figuring on.

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  25. Have you checked the data from the New Horizons KBO search? I think that might cover a chunk of the galactic plane near perihelion fainter than the WISE limits.

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  26. I predict there is no such Planet X. What makes me laugh is that this is all about a .007% chance of something happening and because that 1 in 15,000 chance is unlikely then there must be a planet there. Yet, the probability of the origin of life occurring by chance is a fantastical number far beyond the number of atoms in the entire universe and yet these same people believe that somehow happened.

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  27. Is there any chance that your simulated possible orbits for Planet Nine could be made available? This is what I assume you are graphing as the black curves in the plots above. I am trying to visualize the proposed orbit of Planet Nine, hopefully taking the full range of possibilities into account. MPC 1-line orbital element format would be great. :-)

    Thanks,
    Andy Puckett
    Co-Discoverer of 2007 TG422

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    1. coming soon; coming soon. I promise. We had hoped to release the paper at the same time as the original paper, but we've been a little, uh, busy.

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    2. Thanks, Mike. I am giving a short talk to students in our department tomorrow, hoping to convince them that you have NOT discovered anything, only predicted its existence. I have your nominal best-fit orbital parameters, which will be enough for the talk. I will post the visualization using my OrbitMaster applet shortly (http://tinyurl.com/orbitmaster). I have a version that includes the variant orbits listed in the MPC Ephemeris Service for about 50% of the perturbed objects, which is a nice reminder that all of these orbits aren't perfectly nailed down yet.

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  28. If Planet Nine is proven to exist, how will scientists define the boundary line of the solar system (vs. using the current standard relating to the limit of the heliosheath aka the heliopause)?

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    1. I think that's a misunderstanding. Astronomers consider the Solar System to be the space where objects keep orbiting the Sun. That space is *big*.

      However, I don't know if there's some official number attached to it.

      The outermost border is the Hill sphere of the Sun regarding the Galactic Center, 4 point something light years from the Sun. Beyond that, the Galactic Center's pull will keep objects from orbiting the Sun.

      Somewhere along the way is the point where the gravity of the Alpha Centauri system is stronger than that of the Sun, 1.8 light years from the Sun. To the Sirius system, that point is 3.1 light years away, to all other known stars and brown dwarfs, over 5 light years away.

      (But if there's actually an official size of the Solar System, I'd like to know it)

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    2. AV, thanks for your reply. The confusion about any putative "boundary" of the solar system comes at least in part from NASA when they declared that Voyager 1 had 'officially' crossed over into interstellar space back in Aug-2012 at an AU distance of ~110-115; that's roughly where the speed of the solar wind diminishes down to zero or thereabouts. But if P9 orbits in the 600-1200 AU range, that's 6X+ out into 'interstellar space' by the V1 demarcation definition. Hence why I'm asking a seasoned astronomer like Mike Brown what scientists think about this issue? Does it make any sense to keep calling the terrestrial planets the 'inner' solar system and the giant planets the 'outer' solar system if Sol has yet another "boss" planet in a third zone? Or do we go to a taxonomy that includes an inner/middle/outer solar system? It's certainly an interesting dilemma to say the least!

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    3. Not an expert, but I'm not seeing any big dilemma with nomenclature here. There are any number of known objects (comets, etc) that are bound by the sun's gravity, and their orbits go beyond the heliosphere. If Planet Nine were located, it would be unique in many respects, but "boss" planet would certainly be misleading terminology.

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    4. If P9 exists and is the most 'planet-y' of all Sol's planets--given that gravitational dominance is now the defining characteristic of the IAU 'planet' category--P9 will certainly be the boss planet of the largest part of the solar system hands down (no disrespect toward Jupiter intended) so I think Juno is a befitting name for P9 (but that's another matter). So, again, I would like to know how that potential game changer would redefine what we mean by 'solar system'. Mike?

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  29. I like Diana, goddess of the hunt, even though there's already asteroid 78 Diana.

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    1. Not a bad suggestion. I like Juno as the smaller female consort of Jupiter, or Athena because it sounds better than the Roman Minerva (and Uranus is named after a Greek deity anyway). Whatever the name they choose, I think it should be feminine to help balance out a solar system dominated by Roman gods.

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    2. On the subject of consorts, maybe P9 should be named Salacia, Roman goddess of the sea and consort of Neptune. Everyone's calling P9 a 'mini-Neptune' so why not pair the two planets up accordingly? A match made in the heavens, one might say!

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  30. What about an Earth-mass object--or even a Neptune-mass object for that matter--that migrates, is scattered, or captured at a distance so far from a star that none of the planetary discriminant strategies proposed to date would allow said object to be classified as a 'planet'? It wouldn't make any sense to automatically demote said object (i.e., Earth- or Neptune-mass objects) to 'dwarf planet' status, now would it! 'Rogue' planets, for example, that don't orbit a star are in a class all their own because they don't orbit a star or stellar remnant so that contingency is handled easily enough. But what do you do with freak exceptions: objects that are clearly planets for no other reason than that they're 'big' compared to runts like Ceres and Pluto? It sounds like you need more than one litmus test other than 'clearing the neighborhood' using one of the current planetary discriminant strategies (that happen to work for the moment given our solar system's known configuration) to demonstrate 'gravitational dominance'. What if you had a Neptune-mass object at 10,000 AUs (or some other godforsaken distance) from a star that had a Mars-mass object and an Earth-size object both locked in resonant orbits to the larger object? How would you employ a 'fudge factor' to determine which of these objects is exhibiting 'gravitationally dominant' behavior sufficient to be classified as a 'planet'? A good taxonomy should be able to reasonably cover unforeseen contingencies as well as cover what's already known. Any comments?

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  32. Before getting to wrapped up in potential names, might be a good idea to actually find it first, worry about naming when/if it's detected.

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  33. This Planet 9 prediction sparked again some ETNOs/Planet X interest in me, which was there for some time, especially following your discoveries and activity. Below are just some layman’s musings over grown-ups’ discoveries, and should not be taken too seriously. But, who knows? They might trigger some in-depth calculations.

    I’m saying it plainly: I’m not good at math. I didn’t make any serious calculations. I only used the basic formulae for determining the absolute magnitude and the diameter. But from a visual perspective, looking over the numbers, different tables and graphs, and taking into account the observational limitations (the surveys already done), I surmised that an object of Titan-to-Mars mass or Titan-to-Mars-sized might be found at ca. 170-190 AU (semi-major axis), with a chance of being on the bigger side if it’s currently in the galactic plane. It could have an inclination under 20°. I’m not sure about the eccentricity, in any case <0.8. Probably there are some other limitations that I missed, but could this work?

    I guess the main factors in coming up with this “prediction” were the graphs of a vs. i and a vs. e for ETNOs, and a vs. mass for Solar System objects, where you can see some patterns emerging. I have no idea if this “prediction” is (entirely) compatible with Planet 9. Also, I don’t know if these patterns could emerge from Planet 9’s gravitational influences (resonances, etc.) or some other mechanism. Of course, pattern recognition may be on the wrong side here (with the very few ETNOs discovered), but future discoveries will show if this “hypothesis” is worth a thought. Anyway, to me at least… Unless I receive a straight “Uhh, no”.

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  34. This is a map showing where Planet 9 may be based on Mike's map above, at
    http://www.jasonhigley.com/_/rsrc/1455517013878/home/planet-9-information/TychoSkyMap-WITH-LAYERS-AfterMerge-25PCT-REDUX-ByJasonHigley.jpg

    A key to (to the un-initiated or new to) what his and Konstantin's information is. The Grey wavy swath though the middle of the map represents calculations of the numerous possible paths that Planet 9 could take through the sky and still show the effect being observed on other solar system bodies. The green wavy lines show Mike Brown's markings of where the Milky Way galaxy is located (notice that they enclose the actual Milky Way image map I've added). The yellow wavy line represents The Ecliptic, (which for newbies is the path of the Sun through the sky, but also represents the average location/orbital plane of where most of our solar system planets orbit and move through our night sky). Now for the good part, in the background I've added a map based on the Tycho 2 catalog of 2.5 million of the brightest stars in the sky, as created by NASA/Goddard Space Flight Center Scientific Visualization Studio. Constellation figures based on those developed for the IAU by Alan MacRobert of Sky and Telescope magazine. The original map I've created is too big to put here (128 megs), and is detailed enough to show the grid line numbers clearly. I'd be glad to send it to anyone who requests it via "reachjasonh..." (and add @gmail.com to the end of that).

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    1. Here's the full-sized version of the map I made using as an overlay Mike's/Konstantin's map, onto a Tycho 2 map all-sky map. It's a 17 meg .jpg (down from a 128 .png). The coordinate numbers are visible in this one
      https://drive.google.com/file/d/0ByoMM0soJBiaaGozTThzODBzTm8/view?usp=sharing

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    2. Perhaps you could contribute this to wikipedia as your own work?

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  35. Some reliable-looking people have analyzed the Cassini data and determined that if P9 is located at ν = 117.8° (+11°/-10°), then Saturn's orbital residual is minimized. They also claim that P9 can't be at ν = -130° to -110°, nor -65° to 85°. That would put P9 at 630 AU's approximately. Does this make any sense?

    http://arxiv.org/abs/1602.06116v3

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    1. I don't know - maybe - but does the direction of 120° from perihelion counter clockwise from Aries roughly 30° inclined from the ecliptic end in some discernible direction (if I'm interpreting this right.)

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    2. A fascinating study. How does this line up with the treasure map that's presented here? For example, has the highest-probability zone from this new paper been ruled out by the survey's that are overlayed on the map here?

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    5. The Cassini study suggests looking at a true anomaly of 117.8 degrees.

      If I understand the charts correctly, the planet's path is graphed from right to left. So, start at the minimum distance and continue 118 degrees to the left. You get to RA of 358 (call it zero +/- 10 degrees). That's where Cassini predicts the most likely location of Planet Nine. The excluded areas include the gap marked WISE? and also a narrow band from RA 130 to 110.

      On Twitter @plutokiller said they just imaged Leo and part of Ursa Major to better than magnitude 25. That covers approximately RA 150 to 130, an area that previously wasn't searched deeply enough, and where Cassini offers no opinion.

      So, the remaining un-searched and un-excluded areas seem to span RA 350 to 110, the area around aphelion, including the Milky Way. At the moment that area is in the general direction of the sun. I think those areas would be overhead midnight in September through December. I would assume it's impossible to observe those areas now to sufficient depth.

      Cassini's favorite location would be overhead at midnight just before the autumnal equinox, September.

      Don't trust anything I've said without verifying it. I'm allegedly good at math, but know very little about astronomy.

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    6. In simpler terms, Planet Nine could be in Leo/Ursa Major or somewhere between Gemini and Sculptor. All other points on its hypothetical orbit have already been searched or are ruled out by the Cassini study, if you believe it.

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    7. RA is traditionally measured in hours; simply divide all your numbers by 15. (There’s a very simple and observable reason for this tradition.) Constellation maps thus have increasing RA from right to left if north is to the top; which means Fienga et al. plotting P9’s true anomaly from –180 to +180 degrees left to right (P9 isn’t in a retrograde orbit!) is inverted with respect to the usual maps. Since P9’s perihelion is at 16 hours, then a true anomaly of ~117º would have it at ~ RA 0 hours (with their green zone error margin of about 10 degrees each side). In the ‘treasure map’ this has it around declinations -20º to -40º, in one of four possible constellations: Sculptor, Piscis Austrinus, Aquarius, or Cetus.

      Yes P9 could be in the Leo / Ursa Major area around RA 10 to 12 hours (corresponding to the –100º to –65º minimum), but Fienga et al don’t actually consider that likely or significant since that is where the perturbation residuals have a minimum anyway, without adding in P9; and they predict that future data from Cassini may rule it out before too long.

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  36. Am I reading it right that that is roundly to the right of Orion towards northern Eridanus?

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  37. This is not another thought, but rather at whatever point I am helped to remember it, the straightforward knowledge behind the slant never tumbles to make me feel great. I think we all have recollections from our past we wished we could free our selves until the end of time. http://www.mordocrosswords.com/2016/02/you-right-now-theme-wise.html

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  38. Vulcan has never been used, not sure about Bacchus. (Vulcan was supposed to be inside Mercury's orbit but was disproved by general relativity). I don't know if this has been said, but I'm pretty sure that Planets and Minor Planets can share names, according to the IAU. In that case, Proserpina or Minerva might be an option. Discordia would be an ironic choice.

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  39. I like the name Tartarus for this new planet, the Tartarus was a place where the evil people were punished for their sins, maybe this world need justice and retribution, so in my personal opinion the new planet could represent this ideal of victory over the evildoers. Also, we have Pluto and Eris in the outer solar system, Pluto was the god of death people and Eris promoted a lot of wars and pain between the people, so the correct choice to complete the picture would be a place of final punishment for the evildoers.

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  40. Hi,

    “Look in the direction of the Pleiades!”

    Perhaps this may help your cause … spotting ‘Planet Nine’. ...

    http://iopot.blogspot.com/2016/04/we-may-find-planet-nine-or-some-other.html

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  41. maybe the reason we cant see it is because I know it is probably not true but just a thought that the orbital path is waved like so - - -
    - -

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  42. Fantastic. Exellent page with people who have a genuine grasp of this outer elliptic solar system. Fascinating and thanks to all who have contributed. You widened my knowledge of the solar system. This is how we learn. Consider this shared as much as a can share it.

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