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Astronomers Create 'Treasure Map' To Find Proposed Planet Nine (extremetech.com) 95

Posted by BeauHD from the hide-and-seek dept.
Some scientists believe there is a ninth planet lurking out there in the inky blackness at the edge of the solar system. A new analysis (PDF) supports the notion that there's something out there, and it also narrows the region we need to search if we want to find the contentious Planet Nine. ExtremeTech reports: Astronomers started talking seriously about a ninth planet in 2016 when Caltech's Mike Brown and Konstantin Batygin published a study detailing the unusual orbital behavior of Kuiper Belt Objects (KBOs). These icy chunks of rock orbit the sun out beyond the orbit of Neptune. Pluto might not be a planet anymore, but it was the first KBO ever discovered. According to the original study, the uneven distribution of orbits among KBOs points to the presence of a massive object in the outer solar system. All searches for this planet have come up empty, though. While some astronomers believe Planet Nine is a good explanation for KBO orbits, there has also been intense criticism of the study. Now, Brown and Batygin are back with a new analysis that aims to address some of those complaints. Chiefly, other scientists noted that it's difficult to observe KBOs, so many searches focus on the more convenient regions of the sky. Thus, we could simply be looking a biased data.

The Planet Nine duo kept some of the original KBOs in the new data set, but it also includes new space rocks. They also discarded any object that appeared to be influenced by Neptune's gravity. The updated set of 11 KBOs still shows an unusual orbital distribution. The study claims there is just a 0.4 percent chance that these orbits are a coincidence. A greater than 99 percent chance that there is a massive object affecting KBOs sounds high, but it's actually lower than the chance assigned to Planet Nine in the original 2016 study. You could argue, of course, that this is a much more realistic number.

Based on the new simulations, Batygin has created a "treasure map" of sorts that points the way to Planet Nine's most likely orbital arc. That expansive area crosses the luminous plane of the Milky Way, which might have helped Planet Nine hide from previous searches. This includes a chance in the expected orbit, bringing Planet Nine in closer to Earth. The original analysis estimated it has an orbital period of 18,500 Earth years, but now it's believed to be in the neighborhood of 7,400 Earth years. The pair believe we are only a few years away from spotting Planet Nine, and it may be the upcoming Vera Rubin Observatory in Chile.
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Astronomers Create 'Treasure Map' To Find Proposed Planet Nine More

Astronomers Create 'Treasure Map' To Find Proposed Planet Nine

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  • We would have spotted it by now... its not like we havent been looking.. only the faintest of objects could have gotten by, so if its big like a gas giant then its also some dark mixtures of gasses

    • Re:It cant be a normal gas giant (Score:5, Informative)

      by Sique ( 173459 ) on Friday September 03, 2021 @03:28AM (#61758873) Homepage
      We actually wouldn't. It's still not easy to spot faint specks that far out. Pluto for instance can get as close as 28 Astronomical Units to Earth, while the postulated Planet Nine would be at 380 AU, which is about 14 times the distance, meaning it would 200 times fainter, if it was Pluto's twin. Eris for instance was much closer at around 98 AU, when it was discovered in 2003 (and later it could be found in photos taken back until 1954, but was then unidentified).

      Most Kuiper Belt objects discovered so far are between 35 and 70 AU, less than a fifth of the proposed distance to Planet Nine. And astronomers still discover them mainly when the Milky Way does not cross the Ecliptic, which introduces a large selection bias into the KBO class.

      • Re:It cant be a normal gas giant (Score:5, Interesting)

        by ytene ( 4376651 ) on Friday September 03, 2021 @04:19AM (#61758921)
        If it were a gas giant - as we understand them to be, at least - then we would not be looking for it using the visible range of light, reflected from our star, but with infra-red.

        For example, Jupiter emits a fair bit of infra-red [uoregon.edu], thanks in large part to the heat generated by it's sheer mass. Our system's two gas giants do this as a function of their composition. If there were another gas giant in the Kuiper belt, then it should in theory be emitting quite the IR signature. In fact, there's even a chance that Hubble would have spotted it with NICMOS [esahubble.org].

        • Re:It cant be a normal gas giant (Score:5, Informative)

          by Sique ( 173459 ) on Friday September 03, 2021 @04:32AM (#61758931) Homepage
          Not necessarily. Uranus for instance does not have other energy sources other than the light of the Sun, and thus does not have a very clear IR signature. You are right if Planet Nine was more similar to Neptune, Saturn or Jupiter, which have their own energy sources (about three times the energy they get from the Sun).

          • Re: (Score:2)

            by ytene ( 4376651 )
            NASA defines Uranus as an Ice Giant [slashdot.org], as opposed to a Gas Giant, so is it fair to include it here?

            • Probably, because AFAIK, 'Ice Giant' is a relatively recent classification. It took years for the general public to get used to Pluto not being a 'planet', and THAT was in the news & controversial. I'd guess that 98% of adults older than ~30 probably have no idea that it's an 'ice giant' (vs 'gas giant'), or that there's even such a thing AS an 'ice giant'.

              I mean, hell, I remember once finding a children's book about space travel at my grandmother's house that belonged to my Baby-Boomer uncle. It was pu

      • Re:It cant be a normal gas giant (Score:5, Informative)

        by irchans ( 527097 ) on Friday September 03, 2021 @06:55AM (#61759053)

        If you put a copy of Jupiter at distance d, then it would have a visual magnitude of about

        m
        ~= Mag_Jupiter + 10*Log[ d/ 4 AU] /Log[10]
        ~= -2 + 10*Log[ d/4 AU]/ 2.303

        (I am assuming that the amount of light approximately varies inversely with the 4th power of distance.)

        At d = 400 AU, then

        m ~= 18

        which is bright enough that I think it would have been found by now. (I'm guessing that we have found and tracked all 18th magnitude stars. Maybe this if false for stars in the Milky Way area of the sky.)

        On the other hand, if you put a copy of Neptune at 400 AU, I think that it would have a visual magnitude of

        m
        ~= Mag_Neptune + 10*Log[ d/ 30 AU] /Log[10]
        ~= 8 + 11 = 19.

        (I am not an astronomer, so there might be an error in these rough calculations.)

        ytene suggested that it may be even easier to detect in the infrared.

        • Re: (Score:2)

          by ytene ( 4376651 )
          Interesting...

          Please forgive the ignorant follow-on question, but since the outer planets all have very different appearances - I guess thanks to significant differences in the composition of their atmospheres - could this suggest that a KBO of gas giant size *might* have yet another variation on atmospheric composition?

          If that's a possibility, then what's the least light-reflective atmosphere we can think of... and what would the reflectivity of that be within the orbital ranges suggested? It just se

        • Nice.

          A couple of things.

          Given the mass range in the paper, we're talking more super-earth than ice giant. The smaller size alone could easily add another magnitude.
          The paper's most probable magnitude is 21.
          Eris was discovered in 2005. Its magnitude is 18.7. 20+ is _hard_, especially if you don't known where to look.

        • Re: (Score:2)

          by Tablizer ( 95088 )

          The bottleneck is not spotting it, but rather recognizing it. At those magnitudes, lots of stars will also visible such that it wouldn't stand out. A time-lapse comparison is needed so as to spot it moving between frames. That's how Pluto and Arrokoth were discovered.

          • The bottleneck is not spotting it, but rather recognizing it. At those magnitudes, lots of stars will also visible such that it wouldn't stand out. A time-lapse comparison is needed so as to spot it moving between frames. That's how Pluto and Arrokoth were discovered.

            And the time-lapse trick is much harder with this planet. Pluto averages 39 AU from the Sun. Planet 9 is hypothesized to be 380 AU out, nearly 10 times the distance. That gives it an orbital period of around 7400 years. So, if we had a cand

            • Re: (Score:1)

              by Tablizer ( 95088 )

              My rough calculation is that you'd have to wait only about 2 months to move beyond the resolution error of a typical high-exposure photo.

              Earth's parallax movement perhaps can also be tapped.

    • I think the point is that it big enough to be a planet, but very far away, so it is very dark. There are telescopes that can see very dim objects, and there are zillions of such objects within our field of view. The problem is, to pick out this one very dim object, so we know it is not a distant galaxy or whatever. Planetary motion maybe? Stars and galaxies don't do that. Just guessing.

  • It would be very surprising if there wasn't (Score:5, Informative)

    by zeeky boogy doog ( 8381659 ) on Friday September 03, 2021 @03:10AM (#61758867)
    Observed disks around young stars are enormous in extent. From the early stage protostellar / class 0/1 / deeply embedded objects where the disk is still strongly self-gravitating, through backlit proplyds observable by Hubble in various nebulae (most famously the Trapezium complex in Orion), through late protostellar rubble disks imaged using mm and sub-mm arrays (SMA / ALMA), they all make the extent of our known solar system (call it 40AU) look small.

    These disks are a hundred to several hundred AU in radius, and given the seemingly outright *favorable* conditions for planet formation in the outer regions - well below the snow line temperature, long shearing timescale, and likely too little ionization to drive the magnetorotational instability - it is hard to believe that we would not see objects form at these radii. Thus unless objects that form at a very large radius spiral in a long ways, or the outer regions are not favorable to formation before the star ignites and literally blows the disk away, it would be surprising if there isn't at least one gas ball lurking out there.

    Then again, the observed existence of hot jupiters clearly indicates that yes, an enormous degree of inspiral (presumably clear up to destruction) does routinely occur.

    Planet formation dynamics are an incredibly complex and fascinating subject.

  • Pluto (Score:5, Funny)

    by e3m4n ( 947977 ) on Friday September 03, 2021 @06:12AM (#61759015)
    Its pronounced pluto and we know exactly where it is ;-)

    • Yeah, we had a perfect Planet IX until they voted it off the island.

      Now the same people are demanding a new one.

      • Well yeah, just because we don't serve dwarfs here doesn't mean we don't like other people.

        Honestly all meetings from the IAU should start with "I'm not a planetist but..."

  • Mercury
    Venus
    Earth
    Mars
    Jupiter
    Saturn
    Uranus
    Neptune
    Pluto
    Dave
    Alvin

  • Don't they mean Planet 10? (Score:3, Insightful)

    by neglogic ( 877820 ) on Friday September 03, 2021 @06:57AM (#61759061)
    Our Solar System already has 9 discovered planets.

    • Re: (Score:2)

      by schwit1 ( 797399 )

      Yes. Pluto is a planet.

      We/they are looking for Planet X.

    • Our Solar System already has 9 discovered planets.

      Only for those who never managed to master that old Sesame Street game "One of These Things Is Not Like the Others".

      • Re: (Score:1)

        by jd ( 1658 )

        Except we know Pluto is less like any KBO and any dwarf planet than it is any of the major planets.

        So if we're playing "not like the others", you lost.

        • Re:Don't they mean Planet 10? (Score:4, Interesting)

          by Waffle Iron ( 339739 ) on Friday September 03, 2021 @10:25AM (#61759583)

          Pluto is a tiny ball of ice almost exactly the same size and origin as other balls of ice in the Kuiper Belt, and is physically unlike any of the eight planets.

          Pluto's orbit is highly elliptical, like many Kuiper Belt objects, and unlike any of the eight planets.

          Can you name even one attribute that would actually make Pluto more similar to the eight planets than to its hundreds of cohorts in the Kuiper Belt?

          "Was discovered by a plucky and dedicated astronomer!" doesn't count.

          • Re: (Score:2)

            by jythie ( 914043 )
            It appeared in children's astronomy lessons when they grew up?

            • Re: (Score:2)

              by jd ( 1658 )

              I managed three real intrinsic properties of Pluto. It wasn't hard.

          • Re: (Score:1)

            by jd ( 1658 )

            The orbit is not a property of the object and virtually all exoplanets including superjupiters have highly eccentric orbits. You don't consider those dwarves as well, do you? No? Then the orbit is worthess.

            Qualities of Pluto:

            • It is stratified with a single body and single core. The KBO objects observed at any meaningful resolution are multi-body, multi-core objects with no stratification.
            • It has a liquid core and is geologically active, a quality no asteroid or KBO today can claim, but all planets can.
            • It has

        • Except we know Pluto is less like any KBO and any dwarf planet than it is any of the major planets.

          Just because a Chinese person doesn't have black skin, doesn't make them a Caucasian. There's a reason they adopted another specific definition to help classify Pluto.

          • Re: (Score:2)

            by jd ( 1658 )

            No there isn't. They wanted to avoid having to do more work in schools. That was the line given at the time and I see no reason to disbelieve them. No planetary scientist agrees with the IAU decision and planetary scientists are in fact scientists. Astronomy is listed amongst the humanities.

            • No planetary scientist agrees with the IAU decision

              That's like saying no climate scientist agrees with the IPCC. Sorry but your comment is horseshit. But not just any horseshit. Like real horseshit, like not true horseshit fallacy kind of horseshit.

              No there isn't.

              And yet despite your assertion that "a line was given at the time", what was actually given was long reasoned arguments as to why Pluto differs from both all other planets as well as KBOs, and is precisely why they came up with another definition.

              Be a bit less anti science. Climate change is a thing. COVID isn't

        • The condition for "like the others" was that to be a planet the object has to have cleared its orbital lane, i.e. scattered everything else out of it or hit it. Mercury through Neptune satisfy this, but Pluto is the best known of a cloud of hundreds of trans-Neptunian KBOs in the 3:2 resonance with Neptune, all sharing similar orbital parameters.

          • Re: (Score:2)

            by jd ( 1658 )

            Except we know hundreds of superjupiters around other stars that also haven't cleared their orbit. Defining a superjupiter as a dwarf planet seems kinda stupid.

            We also know that eccentric orbits are the rule amongst exoplanets, which shows Pluto's orbit isn't remotely unusual for super Earths and super Jupiters.

            More importantly, though, that is extrinsic. It isn't a property of the object, but of its environment. In absolutely no field of endeavour do we classify objects like this. An oak does not become a

    • Re: (Score:1)

      by tokul ( 682258 )

      > has 9 discovered planets.

      Had. Past tense. One of those buggers got reclassified as dwarf planet as it could not clear its own orbit and had some large sidekick dangling next to it.

      • Re: (Score:2)

        by jd ( 1658 )

        Except we've seen hundreds of exoplanets, some superjupiters, that also haven't cleared their own orbit. Besides which, that's neither intrinsic, not is it invariant by definition. When devising ontologies, it's important to choose things that actually relate to the object under consideration. It's also important to choose an ontology by merit and not by a very tiny self-selected bunch of people who openly stated it was to avoid doing work with their kids for school.

        • We'll undoubtedly be changing our ontology when (or if) we learn enough about other solar systems that we can tell whether ours is in any way typical.

          • Re: (Score:2)

            by jd ( 1658 )

            We've looked at hundreds, if not thousands, of other solar systems. Ours is very much a rarity amongst the set we have seen. Even if other systems turn up that look like ours, that's an awfully large class of solar systems to ignore.

      • what a dingleberry....

    • No. It has either 8 or (at least) dozens, depending on which definition you use.
      - spherical, in orbit around the Sun and clears its orbit: 8
      - spherical and in orbit around the Sun: lots

      There's no definition based on physics that includes Pluto and excludes Ceres and other minor planets.

    • Really, this whole business about whether Pluto is a planet or not is absurd. The word "planet" is just that--a word. Nothing important comes from calling Pluto a planet, or not.

      Otoh, Pluto is too small (and maybe in the wrong place) to have had the gravitational effects attributed (rightly or wrongly) to Planet X. So again--calling Pluto a planet (or not) does absolutely nothing to clear up the alleged problems with these other bodies' orbits and axis tilts.

  • Why does it matter? (Score:4, Funny)

    by argStyopa ( 232550 ) on Friday September 03, 2021 @07:47AM (#61759145) Journal

    Neil DeGrasse Tyson would just find a way to deprecate it and not call it a planet.

    Pluto-assassinating bitch.

    • Re: (Score:2)

      by HiThere ( 15173 )

      They've already got that in the rules. It clearly wouldn't have "cleared its orbit". (Of course, neither has Jupiter, see the Trojan asteroids, but it's in the rule.)

      • They've already got that in the rules. It clearly wouldn't have "cleared its orbit". (Of course, neither has Jupiter, see the Trojan asteroids, but it's in the rule.)

        The rule should probably be revised to 'cleared or controlled its orbit." Jupiter pins the Trojan asteroids in place. Those are the Jupiter-Sun L4 and L5 Lagrange points, islands of gravitational stability. Any rock that wanders in at a low enough velocity can't get out again. All of the planets have trapped at least a few things in their Sun L4 and L5 points, including Earth. Earth has a Trojan asteroid too, catalog number 2010 TK7. The "cleared its orbit" criteria comes with an asterisk "with the ex

  • Once this was the tenth planet, which had the intriguing enigmatic name "Planet X."

    Until, but then Pluto got plutoed as the ninth planet.

    Still an intriguing possibility. I wish either NASA, ESA, or perhaps the private space firms would send a probe to the other side of the Sun, collect data, and then the probe would return with the data.

    So if there is a "hidden" planet opposite the known planets it could be detected. Easier said than done, such a mission requires out of line of sight for communication, and

    • I wish either NASA, ESA, or perhaps the private space firms would send a probe to the other side of the Sun, collect data, and then the probe would return with the data.

      So if there is a "hidden" planet opposite the known planets it could be detected.

      So...uhm...not exactly sure what you're expecting to find there. Planets move, and all of the planets move at different paces. There is a whole lot of time when we are on the opposite side of the sun as other planets. Uranus and Neptune are particularly prone to this, but you won't be able to see Mars during part of October, either.

      The only way for this to be useful is if there's a planet that is precisely synchronized to Earth's orbit and thus always invisible...also managing to not-appear on any of the do

    • We visit the other side of the sun for quite literally half of every year.

    • As others have mentioned, you appear to have forgotten that everything not at Earth's distance from the sun travels around the sun at a different speed than Earth, thus bringing those objects to "our" side of the sun very frequently.

      Also, a parallel Earth that is directly opposite us relative to the sun would be detectable via the effects caused by its gravity.

      But you're also wrong on this part:

      Easier said than done, such a mission requires out of line of sight for communication, and once deployed the probe would have to be self-correcting, navigating.

      Problems with communication would only happen if the satellite was exactly opposite Earth. You don't have to do t

  • Only a tiny minority of the IAU call Pluto a dwarf planet. Most planetary scientists and a significant number of astronomers regard Pluto the same as they always have.

    As for Planet X, it's almost certainly not a gas giant that far out. If we look at other systems, you don't see many where there's huge planets on the outer edge. They tend to have very eccentric orbits and cut in very close to their sun. Our own solar system featured that behaviour until Saturn formed, which pulled Jupiter into its current or

    • Re: (Score:2)

      by HiThere ( 15173 )

      Your reasoning doesn't work. As planets get farther from their sun, they become more difficult to detect, so there's no reason to expect that we would have detected distant planets around either our sun or any other. And if you've got a huge aphelion, there's no reason to expect a small perihelion, even with a very eccentric orbit. And they'll spend most of their time at the more distant parts of their orbit.

      That said, a gas giant does seem unlikely. But if it were there, it would be likely to not have

  • I don't care what rationale Tyson, et al spew, Pluto is a planet.

    • "Pluto is a planet": so what? or so what if it isn't? It went millennia without anyone knowing it was even there, so how does the category we assign it to change *anything*?

  • | That expansive area crosses the luminous plane of the Milky Way, which might have helped Planet Nine hide from previous searches.

    Doesn't every orbit around our sun cross the plane of the Milky Way?
    Although something slow moving and hiding the the denser parts could be a reason we haven't noticed it.

    • The planets orbit the sun at about a 60 degree angle from the galactic plane, so they cross the plane regularly.

      But there's nothing that requires a Kuiper Belt object to orbit in the same plane as the planets. See: Pluto.

      This one could be in an orbit such that it's always in or very close to the galactic plane.

  • I though Alf wrapped this up decades ago with Dave and Alvin?

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