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Kepler-78b: The Earth-Like Planet That Shouldn't Exist 110

Posted by samzenpus from the hot-hot-hot dept.
astroengine writes "Kepler-78b may be an exoplanet notable for being approximately Earth-sized and likely possessing a rocky surface plus iron core, but that's where any similarity to our planet ends. It has an extremely tight orbit around sun-like star Kepler-78, completing one 'year' in only 8.5 hours. It orbits so close in fact that the alien world's surface temperature soars to 2,000 degrees hotter than Earth's. Referring to Kepler-78b as a 'rocky' world is therefore a misnomer — it's a hellish lava world. But this is just a side-show to the real conundrum behind Kepler-78b: It shouldn't exist at all. 'This planet is a complete mystery,' said astronomer David Latham of the Harvard-Smithsonian Center for Astrophysics (CfA) in a press release. 'We don't know how it formed or how it got to where it is today. What we do know is that it's not going to last forever.'"
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Kepler-78b: The Earth-Like Planet That Shouldn't Exist More

Kepler-78b: The Earth-Like Planet That Shouldn't Exist

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  • It's a Big Universe (Score:5, Insightful)

    by Greyfox ( 87712 ) on Wednesday October 30, 2013 @06:05PM (#45286575) Homepage Journal
    In an inifinitely-ish sized universe, I'd be surprised NOT to find a lot of outliers. Even if it's 99.99999% unlikely ever to happen, there are still an infinite number of them out there! We might even be able to see a couple!

    • Re:It's a Big Universe (Score:5, Informative)

      by harperska ( 1376103 ) on Wednesday October 30, 2013 @06:17PM (#45286705)

      That, and the results of both of our effective planet detecting schemes - transit and doppler - skew proportionately towards these hot worlds, as for both methods a shorter period will give a stronger signal and therefore be more likely to be detected. So just like with the hot jupiters detected by the doppler method, they are probably actually a minuscule fraction of the planets out there but happen to be the easiest to detect. So even though they are rare, we are guaranteed to see them, and then muse about their rarity.

    • Re:It's a Big Universe (Score:5, Informative)

      by IndustrialComplex ( 975015 ) on Wednesday October 30, 2013 @06:19PM (#45286731)

      It's not so much that it's an outlier or unlikely, it's that given our current understanding of planets/orbits/forces, it shouldn't be there at all. ie: There should be 0 planets like it in the universe. It would be like finding a neptune-like planet orbiting a sun-like star at 0.5 AUs, due to the solar wind at that distance, it should only be a 'rocky' planet, not a gas planet. The 'problem' with this planet is that it is too close to the star for it to have formed there, and there is no stable orbital migration pattern which would allow it to have formed farther out and drifted inward as close as it has w/o almost immediately falling into the star itself.

      • Re: (Score:2)

        by AK Marc ( 707885 )
        Given that it evolved within the presumed surface of the star, and there's no "stable" orbital migration pattern which could allow it to be there, are we asserting that reality is wrong, or that the current theories of star development or orbital mechanics are wrong? One of the two must be. Reading the article, they were almost making it sound like it's proof of God. we can't explain it, so it must be supernatural. Rather than "we obviously have some gaps in our knowledge."

        A loose planet captured by a

        • Re:It's a Big Universe (Score:5, Insightful)

          by Teancum ( 67324 ) <robert_horning@netz e r o . n et> on Wednesday October 30, 2013 @07:00PM (#45287037) Homepage Journal

          Part of the problem is that many of the planetary system models have been developed with a sample size of one. That unfortunately skews the results of any such models. Now that there are literally hundreds of planetary systems to examine where the astrophysicists who make up these models can look at actual stellar systems to see how those models compare to reality, I'm sure there are going to be some changes to those models and some new theories put forward.

          As usual, the science press is making up stuff to sensationalize a situation that is admittedly still unknown simply because it takes time to digest all of this new information. I don't think this is a reporter trying to attribute this to the supernatural, but they are trying to make what is otherwise dull news sound interesting.

        • I didn't get the feeling of 'must be a Miracle of God' speculation in the article... Just a bit of sensationalist headlining. It's possible to be completely secular in your reporting and still be sensationalist. No attribution to the divine necessary.

          • Re: (Score:3)

            by AK Marc ( 707885 )
            I'd see a more secular version to be "science under continual improvement" not a "we can't explain the eye, so Creationism must be true" type reporting. Maybe I'm overly sensitive, but the anti-intellectual nature of the US these days rubs me the wrong way.

      • ... given our current understanding of planets/orbits/forces ...

        That's the key.

        It would be like finding a neptune-like planet orbiting a sun-like star at 0.5 AUs, due to the solar wind at that distance, it should only be a 'rocky' planet, not a gas planet.

        Hot jupiters have been found as close as 0.0165 AU from sun-like stars. Again, they're very rare, but they exist.

        The 'problem' with this planet is that it is too close to the star for it to have formed there, and there is no stable orbital migration pattern which would allow it to have formed farther out and drifted inward as close as it has w/o almost immediately falling into the star itself.

        "Stable" is a relative term. According to TFA, Kepler 78b's orbit is unstable, and will degrade in about 3 billion years. "Immediately" in astronomical terms can mean millions or billions of years.

        • I've been wondering for a while if there couldn't just be some coarseness in these measurements and that most of these exoplanets they've detected will just turn out to be chimerical. NOTE: This is just curiosity on my behalf, haven't actually delved into the data, aren't capable of doing so really. But I'd like to know if anyone else has delved into this - which is undoubtedly the case - and if there aren't any solid arguments that many of these detected extrasolar bodies might someday prove to be actua

          • I've just looked at the data from an armchair perspective, but my understanding is that they only declare a signal to be a planet once they are pretty darn sure that it is. Kepler found several thousand planet candidates with a relatively high certainty, but they have so far only declared a few hundred of them as actual planets as they are confirmed by separate observations preferably using different techniques.

            In the case of Kepler 78b, they got both a transiting signal from Kepler and a doppler signal fro

            • Re:It's a Big Universe (Score:5, Interesting)

              by mythosaz ( 572040 ) on Wednesday October 30, 2013 @08:01PM (#45287409)

              Am I the only one who reads these things and goes: "Holy fuck, seriously? We're detecting planetary-caused star-wobble from where? That's how we do this shit?!?"

              • Re: (Score:2)

                by Teancum ( 67324 )

                Doppler shifting of a star though light frequency shifts is something that is extremely accurate and the science involved is understood very well, hence why it is possible to detect planetary shifts in this manner. Keep in mind this technique mostly works because the planetary system (and the orbit of this planet) has its plane edge-on to us here on the Earth. This is the reason why Kepler was able to detect this planet, and why the spectrum of this star is able to give so much additional information.

                If i

              • Am I the only one who reads these things and goes: "Holy fuck, seriously? We're detecting planetary-caused star-wobble from where? That's how we do this shit?!?"

                20+ years ago when I was in university and hung out with astrophysicists, this was exactly what they were talking about. There hadn't yet been any found, so it was still pretty cutting edge.

                I think there's a few ways -- infer the planets from the wobble of the sun, observe a slight fluctuation in the starlight as the planet passes in front, and pos

        • Hot jupiters have been found as close as 0.0165 AU from sun-like stars. Again, they're very rare, but they exist.

          I was trying to come up with an example of something which shouldn't be possible, so I shifted from Jupiter at 0.5 AU to Neptune (assuming it's weaker gravity means that it's gas would be blown away)

          Feel free to substitute your own 'impossible' solar system object.

          "Stable" is a relative term. According to TFA, Kepler 78b's orbit is unstable, and will degrade in about 3 billion years. "Immediately" in astronomical terms can mean millions or billions of years.

          Yup. Literally astronomical. I was mostly glancing at TFA, and I was wondering what they meant by unstable. Did they mean unstable with respect to tidal forces? Or unstable in another manner.

          I really want to know what they mean when they say

      • Re:It's a Big Universe (Score:5, Insightful)

        by mcgrew ( 92797 ) * on Wednesday October 30, 2013 @06:58PM (#45287013) Homepage Journal

        I'm not so sure about that. From TFA:

        So could the planet have formed in a wider orbit and migrated inward? This is another improbability, say the researchers. âoeIt couldnâ(TM)t have formed further out and migrated inward, because it would have migrated all the way into the star. This planet is an enigma,â Sasselov added.

        That is in opposition to this: [nationalgeographic.com]

        âoeWhat Iâ(TM)m going to say is really absolutely crazy,â he said at the start of a recent seminar. âoeIf we publish this, my career might be over.â He could have made the same remark back in 2004 about what is now called the Nice modelâ"the hypothesis that he and his colleagues, including Alessandro Morbidelli of the CÃte dâ(TM)Azur Observatory in Nice, developed on the basis of dozens of computer simulations.

        In essence Levisonâ(TM)s team proposed that our solar systemâ(TM)s four giant planetsâ"Jupiter, Saturn, Uranus, and Neptuneâ"had started out much more closely packed together, on nearly circular orbits, with the latter three closer to the sun than they are now. Early on they were embedded in the disk-shaped solar nebula, which was still full of icy and rocky debris. As the planets absorbed those planetesimals or flung them away after close encounters, they cleared gaps in the disk.

        Because the planets were also tugging on one another, the whole system was fragileâ"âoealmost infinitely chaotic,â Levison says. Instead of each planet being linked only to the sun by a brass arm, itâ(TM)s as if they were all linked by gravitational springs as well. The most powerful one linked the two biggest bodies, Jupiter and Saturn. A yank on that spring would jolt the whole system.

        And that, the team believes, is what happened when the solar system was about 500 million to 700 million years old. As the planets interacted with planetesimals, their own orbits shifted. Jupiter moved slightly inward; Saturn moved slightly outward, as did Uranus and Neptune. Everything happened slowlyâ"until at a certain point Saturn was completing exactly one orbit for every two of Jupiterâ(TM)s.

        Because the planets were also tugging on one another, the whole system was fragileâ"âoealmost infinitely chaotic,â Levison says. Instead of each planet being linked only to the sun by a brass arm, itâ(TM)s as if they were all linked by gravitational springs as well. The most powerful one linked the two biggest bodies, Jupiter and Saturn. A yank on that spring would jolt the whole system.

        TFA is framing the question in a sensational way. What the scientists are saying is "this is an exciting puzzle, it shouldn't happen according to what we know.

        • Oh I definitely agree, it's not that it IS impossible, it's just impossible based on our current models.

          I'm of the opinion that it's a captured exoplanet, or one which suffered a collision and lost angular momentum.

          • Re: (Score:2)

            by mcgrew ( 92797 ) *

            From reading that National Geographic article I suspect this kind of thing is more common than they think. It wouldn't even need a collision, just a close call with a larger body.

            • Re: (Score:2)

              by Zephyn ( 415698 )

              Or leftover dust from the stellar disc that's more prevalent in the outer areas. The orbit gradually degrades until it reaches a clearer area closer in.

        • Re:It's a Big Universe (Score:5, Insightful)

          by harperska ( 1376103 ) on Wednesday October 30, 2013 @08:01PM (#45287415)

          Yeah, when scientists say "This shouldn't happen according to current models", they are really saying "Holy shit, this is awesome! We get to come up with new models!".

          Meanwhile, the mainstream media hears that and reports it either as "Scientists say this shouldn't happen. The universe is fucked up" or "Scientists say this shouldn't happen. Science is fucked up" depending on their political bent.

          • "The universe is fucked up" is something pretty much all scientists can agree on.

            • "The universe is fucked up" is something pretty much all scientists can agree on.

              Reminds me of this classic: There is a theory which states that if ever anybody discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.

        • Re: (Score:2)

          by Xest ( 935314 )

          "What the scientists are saying is "this is an exciting puzzle, it shouldn't happen according to what we know."

          For what it's worth, that's how I read titles like "shouldn't exist" anyway, I assume they're saying "shouldn't exist according to current models and understanding" which ultimately means our current models and understanding still need adjustment and we just figure out how.

          So I wouldn't worry too much about the sensationalism, I think a lot of us even those of us who know little about this sort of

      • Re: (Score:2)

        by jrumney ( 197329 )

        w/o almost immediately falling into the star itself.

        Has it been observed for long enough to know that is not exactly what is happening? "Immediately" on the scale of a planet spiralling into its sun most likely takes centuries, if not millenia.

        • Has it been observed for long enough to know that is not exactly what is happening? "Immediately" on the scale of a planet spiralling into its sun most likely takes centuries, if not millenia.

          I think in most cases, that would be the case. However, this planet has an orbital period of only 8.5 hours! Contrast that with Mercury, which has an orbital period of 88 days. There are just so many opportunities to evaluate this planet it's amazing.

          Since Galileo observed Jupiter's moons in 1610, Jupiter has completed its orbit around the sun approximately 34 times. Since the first publishing of the discover of Kepler-78b (not even it's discovery date), it has orbited its star over 469 times!

      • "Almost immediately" in celestial terms could be 1000 years, or even a million. That's a blink of an eye, but it will happen... it will just usually be over before we look. This time, it's not.

      • It's not so much that it's an outlier or unlikely, it's that given our current understanding of planets/orbits/forces, it shouldn't be there at all. ie: There should be 0 planets like it in the universe. It would be like finding a neptune-like planet orbiting a sun-like star at 0.5 AUs, due to the solar wind at that distance, it should only be a 'rocky' planet, not a gas planet. The 'problem' with this planet is that it is too close to the star for it to have formed there, and there is no stable orbital migration pattern which would allow it to have formed farther out and drifted inward as close as it has w/o almost immediately falling into the star itself.

        Two possibilities: either the data is wrong or the theory is wrong.

        Side note - It does not seem completely impossible, only extremely improbable, that a large meteor might fall close to the sun and end up being captured by it's gravity well and end up in a stable (or close to) orbit.

        Disclaimer: I freely admit that I have no idea what I am talking about.

    • I'm no mathemologist but, if something is 99.99999%, I believe that means we should expect to find 1 instance in 10,000,000 samples. So should we consider it odd if we actually find 1 within the first 1,000 samples? It's not impossible but it's probably something like 99.99% unlikely.

      • It would be odd to find 1 in the first 1000 samples if the probability of detection was the same for every object out there. But not all planets have the same probability of detection.

        The shorter its orbital period, the more likely it is that it will be detected as it will take less time to determine a pattern. Consider, it would take E.T. multiple years to detect Earth simply because they would have to detect multiple transits of Earth across the sun which of course happen once a year. It might take them 1

    • We had the technology to detect planets for at least 80 years yet the first efforts started just 30 years ago. You know why? Because our star system model predicted that there are no planets that meet the condition to be detected by us (big, close to the star).

      A model based on a sample of one system.

      After people discovered a whole bunch of such planets, I thought that people would realize that they should not judge the universe based on just our solar system, but here it is all over again.

    • Re: (Score:2)

      by Trogre ( 513942 )

      True, I guess. Though taken to its conclusion it does lead one down the path of thought towards Hitchhikers Guide absurdities such as tools growing on trees or wild mattresses.

  • The answer is obvious. They didn't find a hellish rocky world; they discovered Hell. Naturally, this verifies quite a few things.

    • Re: (Score:1)

      by Anonymous Coward

      So now we just need to find the Heaven planet, and make peaceful contact.

      Then we invade.

  • "2000 Degrees," eh? (Score:1)

    by Anonymous Coward

    It orbits so close in fact that the alien world's surface temperature soars to 2,000 degrees hotter than Earth's.

    Celsius? Fahrenheit? Kelvin? Rankine? What kind of idiots are they hiring at Discovery.com nowadays?

    • Re: "2000 Degrees," eh? (Score:1)

      by Anonymous Coward

      Kelvin. They use Kelvin when the topic is ET worlds unless otherwise specified.

      • Re: (Score:2)

        by _merlin ( 160982 )

        That wouldn't make sense at all, as it would be 2000 Kelvin, never 2000 degrees Kelvin since it's an absolute scale.

    • Re: (Score:3)

      by rjch ( 544288 )

      Celsius? Fahrenheit? Kelvin? Rankine? What kind of idiots are they hiring at Discovery.com nowadays?

      When you're talking about those kind of temperatures, it hardly matters. Rock melts at anywhere between 700 to 1200 degrees Celsius. 2000 degrees Fahrenheit is about 1100 degrees Celsius - still hot enough for rock to at least partially melt.

      In any case, there are only *two* temperature scales that you have quoted there that result in different answers. The only difference between Kevin and Celsius is the base temperature - a difference of one degree Kelvin is exactly the same as a difference of one degr

  • the American public agrees that Wall Street should be moved to Kepler-78b.

    • the American public agrees that Wall Street should be moved to Kepler-78b.

      We just need some clever marketing and we can get them to go volunteer. It should go something like this:

      Tired of those long work hours? Move to Kepler-78b! With it's synergistic proximity to its sun, you can implement an entire year's worth of productivity in just 8.5 hours thereby streamlining your cloud solutions on a quantum scale (exponentially). Who wants to deal with those long brutal winters in NYC? We have nothing but sun. In fact K78b's integration with a self sustaining source of clean energy

  • I think a planet like this is just more data backing up the rogue planet theory that some planets have formed either outside of solar systems with a star and/or have been flung out of their solar system when the system came too close to either a black hole or other solar systems. Or for transference of a planet from one solar system into another.
    • Actually, I would expect binary star systems to be much more likely candidates for origin of rogue planets.

    • Re: (Score:2)

      by Teancum ( 67324 )

      The problem is that the orbit is roughly circular in nature, thus why it is presumed there is some other mechanism at work. If the planet was orbiting in a highly elliptical orbit (such as is the case with many comets as seen in our solar system), it would make sense. That would have been detected from the combination of methods which were used to identify this planet.

      Possibly there might be some other planets in this planetary system which could have helped to "circularize" the orbit. That is the big qu

  • ... I mean, wouldn't this "icarus planet" also suffer severe weathering from the stellar wind? How would that effect compare to the tidal stress induced breakup in 3 billion years?

    Perhaps not strictly sublimation, if the rock turns to liquid first, but, y'know, made a better title, right?

  • Just another no daylight slam.

  • Selection effects (Score:4, Informative)

    by Michael Woodhams ( 112247 ) on Wednesday October 30, 2013 @07:00PM (#45287033) Journal

    A great many of the known exoplanets are large, close to their star or both. It should be noted that this does not directly represent how common large close in planets actually are.

    We find exoplanets in two ways - by Doppler shift of the star, or by transits.

    When a planet orbits a star, the star also orbits their common center of mass, so it wobbles slightly. By looking for subtle Doppler shift in its spectral lines, we can try to detect this wobble. The larger (mass) the planet, the further the star wobbles, and the larger the Doppler shift. Similarly, the closer the planet, the faster (and so more detectable) the wobble. (Even though it has less distance to travel, this is more than compensated for by how much shorter the orbital period is.)

    When a planet transits its star (moves between the star and us) we can detect a decrease in the received light, as some is blocked by the planet. The larger (radius) the planet, the greater the decrease, and so more likely we'll be able to detect it. The closer the planet, the more likely that chance alignment will allow us to observe a transit. Also, the closer the planet, the more frequent the transits, and so the more chance one will happen when we're observing the star.

    So this weird planet was quite possibly thousands of times easier to detect than an Earth-like planet in an Earth-like orbit. (In this case, discovery was by transit, targeted observations measured the Doppler shift. The combination allowed an estimate of its density.)

    • Re: (Score:2)

      by Ihlosi ( 895663 )
      We find exoplanets in two ways - by Doppler shift of the star, or by transits.

      Don't forget finding them by microlensing events, direct observation, and (possibly, in the future) astrometrics (i.e. actually observing the star change position).

  • See! See! (Score:5, Funny)

    by Ol Olsoc ( 1175323 ) on Wednesday October 30, 2013 @07:13PM (#45287115)
    Scientists don't know something! This only proves that Global warming isn't real, that evolution is a farce, and the world was created in 4004 b.c.
  • This is Ceti Alpha V.

    Seriously though, a larger planet cracking or the surface being blasted away by stellar wind is the best bet, especially since the orbit lacks the eccentricity of a captured planet that came from elsewhere.

  • I think the coolest thing about this, and planets like it, are if you were in a spaceship, fairly close, you could watch it swing around the sun in real time. Like a slow clock hand... or actually, I suppose, a fast one.

  • ...That's one rainbow world down, we'll be swimming in sweet, sweet Melnorme trade credits in no time now.

  • filmed there on Crematoria?

  • Earth is too cold for anyone to live. :p

  • What's interesting is that all the metals on the planet if entirely molten could be found and siphoned off from orbit if we had the technology to do so. It would be like guessing the layers of an onion more or less. Gold and other metals would be at certain depths based on their weights compared to others.

  • We know rogue planets and black holes roam the space between the stars. If this planet truly could not have formed there, gravitation interaction with a transient high mass object seems like a probable culprit. Or perhaps the planet itself was once rogue, happened along, and then fell into an unfortunate orbit.

    I'm sure scientists are already pondering these possibilities, but I didn't see it in the article.

  • Push (Score:2)

    by Meneth ( 872868 )
    Perhaps the pushing effect of solar radiation and solar wind keeps it from falling into the star.

  • Is it possible that the planet formed further out, is falling in, and we just were lucky enough to have caught it before it falls in? (Of course, given distances and the speed of light, it's probably already fallen in.)

  • "If it happens it must be possible"

  • to page The Doctor to this one...

  • This reminds me an old story here in slashdot (about the hot jupiters): http://science.slashdot.org/story/09/08/27/1237251/Astrophysicists-Find-Impossible-Planet [slashdot.org] We are improving the search of impossible planets!

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