Second Planetary System Like Ours Discovered

Article written: 27 Nov , 2013
Updated: 23 Dec , 2015

A team of European astronomers has discovered a second planetary system, the closest parallel to our own solar system yet found. It includes seven exoplanets orbiting a star with the small rocky planets close to their host star and the gas giant planets further away. The system was hidden within the wealth of data from the Kepler Space Telescope.

KOI-351 is “the first system with a significant number of planets (not just two or three, where random fluctuations can play a role) that shows a clear hierarchy like the solar system — with small, probably rocky, planets in the interior and gas giants in the (exterior),” Dr. Juan Cabrera, of the Institute of Planetary Research at the German Aerospace Center, told Universe Today.

Three of the seven planets orbiting KOI-351 were detected earlier this year, and have periods of 59, 210 and 331 days — similar to the periods of Mercury, Venus and Earth.

But the orbital periods of these planets vary by as much as 25.7 hours. This is the highest variation detected in an exoplanet’s orbital period so far, hinting that there are more planets than meets the eye.

In closely packed systems, the gravitational pull of nearby planets can cause the acceleration or deceleration of a planet along its orbit. These “tugs” cause the variations in orbital periods.

They also provide indirect evidence of further planets. Using advanced computer algorithms, Cabrera and his team detected four new planets orbiting KOI-351.

But these planets are much closer to their host star than Mercury is to our Sun, with orbital periods of 7, 9, 92 and 125 days. The system is extremely compact — with the outermost planet having an orbital period less than the Earth’s. Yes, the entire system orbits within 1 AU.

While astronomers have discovered over 1000 exoplanets, this is the first solar system analogue detected to date. Not only are there seven planets, but they display the same architecture — rocky small planets orbiting close to the sun and gas giants orbiting further away — as our own solar system.

Most exoplanets are strikingly different from the planets in our own solar system. “We find planets in any order, at any distance, of any size; even planetary classes that don’t exist in the solar system,” Cabrera said.

Several theories including planet migration and planet-planet scattering have been proposed to explain these differences. But the fact of the matter is planet formation is still poorly understood.

“We don’t know yet why this system formed this way, but we have the feeling that this is a key system in understanding planetary formation in general and the formation of the solar system in particular,” Cabrera told Universe Today.

The team is extremely hopeful that the upcoming mission PLATO will receive funding. If so, it will allow them to take a second look at this system — determining the radius and mass of each planet and even analyzing their compositions.

Follow-up observations will not only allow astronomers to determine how this planetary system formed, it will provide hints as to how our own solar system formed.

The paper has been accepted for publication in the Astrophysical Journal and is available for download here.

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64 Responses

  1. Kathleen Sisco says

    Now we can get on with the discussion of how giant red stars implode under magnetic duress and in doing so offload the ‘dirty gas’ that constitutes the rocky inner planets created inside the previous orbit of the red giant. They can’t be that rare if we are seeing them in Kepler data. But perhaps they are ephemeral results of the created magnatar? Life is not so rare just fleeting.

    Carl Sagan said we have to get off planet E; hopefully we already have.

  2. usmcmailman says


  3. fatwillie says

    Don’t buy into this people. its three card monty, and you know not that you play the game. There are no aliens, but what could be accomplished by making you believe it is in the game plan. There is no astroid going to hit you any time soon, but what could be accomplished by making you believe it is evil.

    • Jeremie says

      What are you even talking about? They never mentioned anything about life if that’s how you take it so be it , Thanks for sharing this article.

  4. How Not To Play The Game says

    Project Blue Beam. I have front row tickets. I have got plenty of jiffy pop and Dr. Pepper. Watching stupid even get more perplexed will never be so much fun as it is going to be when the real theater comes to town. Don’t come knocking on my door, for all you will get is the sound of the most sinister, deranged, laughter from hell that you will have ever heard.

  5. Get Real says

    Poor Kathleen….. you and Sagan hoping on the stars.

  6. philw1776 says

    Have the trolls discovered this site? Hope ESA gives PLATO the green light

  7. Jeff, CO says

    Interesting, though it seems odd to call it an analogue of our solar system when it’s so compact.
    On a side note, what the hell is everyone in here talking about? lol

    • Anthony says

      i was thinking the same thing

    • SKAN ONE says

      really though…

    • Every time a closer analogue of our solar system is found, newspapers will say “Analogue of our solar system found”. It will be confusing.

    • It true that this system is very different than ours, but it’s the most similar yet discovered.

      They totally dropped the ball not stating how far away it is…

      KOI-351 (also known as Kepler-90) is about 2,500 light years away.

      • Matt RhinoSheen Milton says

        Maybe afterwards we can work on turning lead into gold.

      • Christian Giordano says

        We can already do that in particle accelerators….

      • Benender says

        “Can we stop wasting time on trivial matters here on Earth and focus all of our talents on developing faster-than-light travel?!”

        I say this ALL THE TIME! We could and SHOULD be colonizing other planets already. If nothing else we could all live on different planets if we cant get along and be fine until we kill each other later!

      • disqus_RgmYjLVRnQ says

        Yeah I Agree, Because of the dumb-ass people and greedy governments of our world we don’t have the technology to build space craft with the means to travel to these worlds and chart solar systems. We will not have the means to explorer space and travel to other worlds until the people and governments of earth come together as one and put aside there wars and conflicts to come together in peace and understanding of our world with the meaning of achieving the universal goal of bettering man-kind. Exploring Space and Traveling to other worlds would also open up so many other jobs opportunities, technologies, medical breakthroughs, mineral resources and so many other advances and opportunities. As long as man-kind keeps acting primitive and wanting to commit acts of violence and cause wars between nations just to silver line their pockets for money and greed….

    • xthorgoldx says

      The article poorly emphasizes how it’s an analogue, which I think is the key term here. It’s not a *parallel* to our solar system (in that it’s different in many ways), but it’s similar in one specific feature – the organization of rocky planets in the center of the system and gas giants in the outer rings. In this regard, it’s the closest star system to the Sol system known to date.

  8. Anthony says

    thank you for sharing Shannon hall, that was a great article. Can’t wait to read more

  9. Grimbold says

    Imagine what the night sky would look like on one of these planets. Most of the others would show as distinct disks instead of points of light, and if the planets have moons of their own it would be a very impressive sight.

  10. BillClinton says

    The article didn’t say anything about the star. Since all the planets are within the orbit of Earth, the star would have to be smaller and/or put out less energy than the Sun. Otherwise all the planets would be roasted, and it would be nothing like our system of planets. Perhaps you could have life on moons of the outer gas giants.

    • Grimbold says

      The scientific article in the link says the star has a radius of 130 Earth radii and a temperature of 5,900K. That makes it very slightly bigger and hotter than the Sun.

    • Barring a copy of our system being found, I would say “rocky interior planets, gassy exterior planets, 330-day orbit” is pretty darn close to analogous.

      • luke says

        @Bryan Curley
        “probably” rocky interior planets and gassy exterior planets.
        At the end of the day, they’re looking at a point of light 2500 light years away that shifts left for a month then right, the left again 75 days later until it dims for 3 days then it looks like it wobbles for 17 days, and after all this, the computer says “star with 7 planets”
        They really have no idea what they’re looking at if you ask me, except a point of light 2500 light years away that we’ll never get to.
        But hey, they said it’ll help us understand things better if we can spend A LOT of money looking at it some more.

    • zengardener says

      The largest planet has an orbit almost exactly the same as Earth. It is supposed to be a gas giant, but it might have a rocky moon.
      That would be cool.


  11. Doug Kolata says

    people as much as steve qualyle claims he is a chrstian he denies the torah of YHWH he is a FALSE messenger…be aware!!!!!

  12. Steffen says

    Nowhere in this article does it denote where it is located, or how far from our solar system this is. I wouldn’t mind knowing this… It would also be nice (for people like me) to explain the statement “Yes, the entire system orbits within 1 AU.”

    • JP Powell says

      An AU (Astronomical Unit) is the distance between the Earth and our Sun.
      Them saying that the entire system orbits within 1 AU would be like having all the planets in our solar system between the Sun and the Earth.

  13. jsispat says

    Earth itself is a single giant living organism and result of single carbonaceous meteoroid. as one tree is a result of one seed same one planet is a result of one seed or meteoroid contain amino acid and organic chemistry.

  14. Christoffer Olsson says

    Without thinking too much about it, it makes me kind of jealous to have all the bodies of the system so close to one another for easier access with space missions.

  15. Haze says

    AU stands for astronomical unit. One AU is the distance from the Sun to the Earth’s position in orbit around it. Saying “the entire system orbits within 1 AU.” means the entire system is squeezed into the seven planets orbit in a distance no farther than the Earth (3rd rock) is from the Sun

    • Steffen says

      So does that mean that the system is so small that all 7 planets are squeezed into the same distance as Earth is to the sun? In other words, if that were our solar system, no planets would be past the Earth in the rotation of the planets? … but the main thing I was saying is.. it would have made more sense to include that information in the original article, rather than having someone explain it in the comments… And there still isn’t a location for the system. How far away is it? In a specific galaxy? “It’s all about location, location, location” lol

      • Haze says

        Exactly. Seven planets would be compressed into the Sun to Earth distance and none beyond. And I agree I was also looking for info about how far it might be from us. I would assume its in the Milky Way I don’t think we can detect systems this accurately in other galaxies yet

      • Xjph says

        The article tells you what star they orbit. You’re not going to get more specific location information than that…

        For the record, it’s ~2500ly away.

      • Steffen says

        We have already seen other systems in other galaxies.. Gliese 581 is 20 light years away, and we have seen the system (Including the possible “Goldilocks” planet Gliese 581g)

        Found a little bit of info here:

        and here: has a small article on it from 2010, so this system has been known for 3 years now. I did a basic search and the ONLY info on it’s location is that it is roughly 2,500 light years away, yet there is NO information as to what galaxy it is in. What galaxies are that far away?

      • Haze says

        The Milky Way is 120,000 light years in diameter. Exoplanets are outside the solar system. What you’re talking about (beyond the milky way) are extragalactic planets. G-581 is within the milky way

      • Steffen says

        Wasn’t aware the milky way was that large. Thanks for the clarification!

      • Richard_L_Kent says

        “Space is big. Really big. You may think it’s a long walk to the [drugstore], but that’s peanuts compared to space.” – Douglas Adams

      • Richard_L_Kent says

        As is this system. 2500 LY is actually in the same galactic county, not neighborhood.

      • wethrowpie says

        You don’t understand the distances being discussed. Please read up. Those systems are within the milky way.

        Maybe you don’t understand the difference between a galaxy and a solar system?

      • Jas Strong says

        The galaxy we live in is 70,000 light years across. Gliese 581 is in our galaxy; heck, it’s in our neighbourhood. We do not yet have the technology to detect planets in other galaxies.

      • Geoff Robbins says

        That’s a tiny distance on intergalactic scale, it’s just another star in our galaxy, which is about 120,000 light years across. The closest galaxy to us is Andromeda, about 2.5 million light years away.

      • Kayti says

        The conversation you guys just had, where one of you asked a question and the other explained it without sarcasm or snark and even clarified when necessary, is the kind of conversation that happens way, way too rarely. It brought a little bit of light into my life. Thank you.

      • Stepan Arkadyevich Oblonsky says

        There is a rather large diagram right at the top explaining exactly this. Maybe the German planet names confused you.

  16. Haze says

    How old is this system compared to our solar system? Maybe its still very young,over time the planets might drift further and further out

  17. Oscar Pitchfork says

    WOW! And if we leave right away in a ship going 67 million miles per hour, we’ll be there in a short 25,000 years! Why do they continue to report this crap?

    • realitycheck says

      to people 1000 years ago flying was an impossibility. Why bother?

    • Matt RhinoSheen Milton says

      Why are you reading it?

    • Geoff Robbins says

      If we had a ship that could accelerate at 1g for a prolonged period then the round trip would take a little over 30 years for the astronauts. It’ll be about 5,000 years from Earth’s perspective, but the rest of us having to wait is a pretty selfish reason not to let people go.

    • philip weber says

      For the same reason people read about stuff they’ll never see or experience. It’s interesting and informative. Why be so close-minded? Would you have said the same thing about the computer back when it was the realm of the impossible? You sure seem to be taking advantage of it now. Try seeing the bigger picture here.

  18. Vertigo Manchmal says

    I suppose it’s too late for accurate terminology. It’s called the solar system because our star is named Sol. So it’s not “our” solar system in comparison to others, it’s the only Solar system. The others are star systems. The Solar is “our” star system. But, never mind.

    • Chris says

      not exactly. “star system” implies a system of stars (binary, trinary, etc.), whilst “planetary system” means a system of planets (by it’s term i think you could have figured that out).

      nowadays, “solar system” just means a system of planets around a star anyway.

  19. Red Rodriguez says is the exoplanet log about this system. The planet with the orbital period of 331 days is roughly the size of jupiter. Also this is the planet that is about the same distance from it’s star as the earth is from sol. If you want to use this in some Drake-like equation or consider the likelihood of life existing in this system,
    Since the star is slightly larger, hotter, and more massive than our sun the habitable zone is actually 1.23-2.13 AU. Considering the ranges of possible error there may be a moon of KOI-351h that could support life.

  20. Tony says

    the article .. is a starting point… jeez

  21. Dr J says

    The ability to find exoplanets like these is really in it’s infancy. Billions of stars will contain the same planetary structures and will depend on the materials first present in the early solar systems during coalition and non will be exactly the same as ours but what’s important for our discovery is if they have ‘Life Jim’ hopefully as we know it. Self aware and inventive monkeys like us!

  22. Steve Walsh says

    Whos up for moving to Earth 2?

  23. Halfload says

    Hang on a second now… I thought we did away with analog when we got rid of 8 tracks. Ohhhh……

  24. Richard_L_Kent says

    I expect both discoveries will be made at the same time.

  25. Sonokar says

    In reality, nobody has ever actually seen a planet outside our solar system. Until we see pics, they don’t exist.

  26. Benender says

    Exactly. I imagine t will take alien life attacking us or an epic worldwide disaster to FORCE us to take responsibility for our race as a whole. I see my children and I have hope. I see others’ children and lose it as fast…why is it that something which to me -and many who have even thought about it – SHOULD be common sense…is so very hard for so many others to grasp?

  27. Calmly screaming says

    Being 2,500 light years away, if they’re looking at us, they’re seeing a world 500 years before Jesus walked the earth.

    The first television if we could beat light to it.

    It took 13.7 billion years for us to get to this point, so if we saw similar anywhere else, they would be WAY ahead of us in evolution.

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