Follow Slashdot stories on Twitter


Forgot your password?
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Our Solar System: Rare Species In Cosmic Zoo 197

astroengine writes "Pulling from 20 years of research since the first discoveries of planets beyond our solar system, scientists have concluded that Earth and its sibling worlds comprise what appears to be a relatively rare breed in a diverse cosmic zoo that includes a huge variety of planet sizes, orbits and parent stars. The most common systems contain one or more planets one to three times bigger than Earth, all orbiting much closer to their parent stars than Earth circles the sun, says astronomer Andrew Howard, with the University of Hawaii."
This discussion has been archived. No new comments can be posted.

Our Solar System: Rare Species In Cosmic Zoo

Comments Filter:
  • by Anonymous Coward on Thursday May 02, 2013 @11:33PM (#43617425)

    That's because the current methods used to detect exoplanets are biased towards large close in planets. As technology progresses we will get more diversity.

    • Remember when exoplanets were said to be a " Rare Species In Cosmic Zoo"
    • True, true.

      But what bothers me is that I have no idea what "one to three times bigger" means.

      I understand "one to three times Earth's size", and I understand "two or three times as large" and "twice as big". But I don't understand "one to three times bigger".

      I suppose logically, "one time bigger" would mean twice the size. But then "two times bigger" would mean three times the size, and so on. I get the feeling that's not what he meant.
    • Diversity (Score:5, Funny)

      by gillbates ( 106458 ) on Friday May 03, 2013 @01:46AM (#43617805) Homepage Journal

      I would posit that we'd have more diversity if scientists stopped being so conservative about what qualifies as a planet.

      Take, for example, the plight of Ceres []. Residing somewhere between Mars and Jupiter, it's been called a dwarf planet for quite some time, just because of its immutable physical characteristics. Size discrimination is very real in the physics community, a practice which continues to this day.

      Imagine how many more planets we'd be able to discover if we'd just liberalize the definition of a planet. I know it's served us well, but it is time to redefine the term planet to be more inclusive of our increasingly diverse universe. And how, exactly, would this hurt the status of existing planets? I know it wouldn't affect my planet.

      And why, exactly isn't Ceres a planet? Because the IAU decided to redefine the term "planet" to exclude it! Such blatant bigotry has no place in a pluralistic universe. We should be ashamed.

    • by symbolset ( 646467 ) * on Friday May 03, 2013 @02:44AM (#43617987) Journal
      What AC said. Almost all stars have at least one, usually two or three, rocky bodies in the habitable zone. Sometimes they are moons, sometimes planets. But they are almost always there. The exceptions are obvious: stars with stars in that zone (tight binaries), exploded stars, stars that are too young to come steady, Population III stars poor in metals and so on. When we can see them, we will find them. Until then, studies like this that survey observations that could not see such a thing are just a waste of time.
    • mod parent up even higher than 5.

    • Re: (Score:2, Funny)

      by Anonymous Coward

      Indeed, similar to:

      "Scientists combing streetsides for spare change in the middle of the night have found that most dropped change tends to be under street lights or other forms of illumination, causing them to speculate that the coins may be exhibiting a photophilic movement".

  • by Anonymous Coward on Thursday May 02, 2013 @11:35PM (#43617433)

    We're still really bad at detecting planets that are NOT bigger than Earth and orbiting much closer to their parent stars? Seriously, whether we use light occlusion or observing the star's wobble, this is the only type of planet we know how to detect.

    Turns out if you're color blind, red and green are very rare and special colours.

    • We are actually pretty bad at detecting small objects that are orbiting our own sun! I agree that our detection methods have a strong bias for larger planets in near orbits to their star. However, it is still interesting to read that Jupiters are less common than Neptune sized planets.

      Still, it's a nice article. I didn't know the counter for exo-planets stood at 900 already. Awesome.

  • Observation Bias (Score:5, Informative)

    by Anonymous Coward on Thursday May 02, 2013 @11:42PM (#43617465)

    I was under the impression that this was agreed to be due to observation bias. That is, it's a hell of a lot easier to find planets bigger than Earth orbiting at frequent, highly periodic intervals than to find anything else.

    • by ( 1140205 ) on Thursday May 02, 2013 @11:52PM (#43617485)
      Using any of the techniques of observation of extra-solar planets it needs 3 orbital periods to confirm a planets existence, with Kepler observatory this means only planets with a period of 1y can be confirmed. Jupiter has a period of 11.9years, so observations of nearly 36 years are needed for this planet and Neptune is 164years, thus requiring observations over nearly 500years, and then for the outer dwarf planets the observation time needs to be over 1.5 millennia. So, obseratvion of 20 years means the search has only started and not that this solar system is weird.
  • Good! Rare is many according to the law of big N

    Rare?! If only one in a million fits, that would be an enormous amount of habitable planets!

    They had examined 900 in detail and and already concluded that a few might fit. Well, it sounds more like one in a hundred, which then would be even more GREAT!

  • So instead of billions of solar systems like ours, there are just millions. And in at least thousands of those millions, there is probably some poor shmuck like myself posting from their parents basement!
  • by huckamania ( 533052 ) on Friday May 03, 2013 @12:58AM (#43617683) Journal

    If we stay on this rare planet, we are certainly doomed. It's the nicest place we know of but if we don't get off this rock, we'll probably get killed off by collision with a smaller rock. Or a super volcano... Or Mannian hot air... Or the next ice age... Or our own greed and stupidity.

    My money is on the Bransons and Rutans of this world figuring out how to get us into space and someday stay for good. Once someone figures out how to survive in space, there will be thousands hot on their heels. We don't need another Earth. If we can survive long enough to get there, the only reason we'll stay is for variety, not neccessity.

    There are more raw resources between the orbits of Mars and Jupiter than exist on Earth. We just need to get there.

    • Re:And yet... (Score:4, Interesting)

      by tehcyder ( 746570 ) on Friday May 03, 2013 @09:00AM (#43619541) Journal

      Once someone figures out how to survive in space, there will be thousands hot on their heels.

      Why? I really don't see that there are going to be "space miners" hacking out asteroids with picks and shovels. Surely it would be easier (and cheaper) to get robots to do it all?

      And apart from harvesting raw materials, who the fuck else would want to live in space for more than a few months until the novelty value wore off?

      To paraphrase Samuel Johnson on being in the Navy: no man will live in space who has contrivance enough to get himself into a jail; for being in a spaceship is being in a jail, with the chance of being asphyxiated, dying of radiation poisoning or irreversibly altering your muscles and organs. A man in a jail has more room, better food and commonly better company.

  • by kenwd0elq ( 985465 ) <> on Friday May 03, 2013 @01:09AM (#43617721)

    The problem isn't that there are no planets in more distant orbits; it's that the Kepler Space Telescope is designed to detect occultations, when a planet passes between the star and us. I am frankly ASTONISHED that Kepler has discovered SO MANY planets in so close to the parent star, but a civilization in the Tau Ceti or even Alpha Centauri system would never be able to detect the Earth - because none of our planets ever occult the Sun from their viewpoint.

    Look up in the night sky, and imagine those distant (and very hypothetical!) civilizations orbiting those many, many stars and trying to find US.. Using a Kepler-type telescope, ONLY civilizations that are pretty darn close to the ecliptic would be able to detect OUR solar system.

    For Kepler to have discovered so many planets, there must be planetary systems around virtually every star out there. There may be a trillion stars in the Milky Way. If only one in a million planets host anything even remotely resembling "life", there must be a million planets with some form of life.

    • by bruce_the_loon ( 856617 ) on Friday May 03, 2013 @02:46AM (#43617991) Homepage

      Precisely. Kepler's been up and observing for 4 years now. Since it hunts for occultations, the scientists can only be certain that observed planets are alone out to a 4 year orbit, which excludes anything outside of Mars in our system. And that is if the system is aligned so that the orbital plane is correctly positioned for Sol-visible occultations.

      For a star where Kepler has observed something, they can only say there's no planets inside 4 year orbits, everything else is speculation. For a star where nothing has been observed yet, they can't say anything with certainty.

      • by bidule ( 173941 )

        And that is if the system is aligned so that the orbital plane is correctly positioned for Sol-visible occultations.

        You can extrapolate from that since 1 in a 100 or 1000 is aligned and multiply the discovery by 1000 to find how many there really are. If this covers a good fraction of the (lets say K) population within a 100 ly, it might not leave much for other types of solar systems.

        I don't think we have enough statistical certainty to reach a conclusion yet because the back of my envelope is full.

  • by mha ( 1305 ) on Friday May 03, 2013 @01:55AM (#43617837) Homepage

    The (Nobel price winning) psychologist Kahnemann calls this phenomenon "What You See Is All There Is" - and he detected in the "experts", not in space.

  • Most exoplanets are much bigger and closer to the sun than Earth is... incidentally, these are the kind of planets that are most easily detected.

    'nuff said.

    • Obviously it's not "most planets are bigger than Earth", it's very exactly "our present detection method being a measure of star movements due to the planet presence, we only see enormous jupiter-like things for now".
      How to say it politely?
      "I hope the OP summary is, er, too concise, otherwise this just means Hawaii climate turns the scientists silly..."

  • ...scientists take a measurement that's known to be valid in only a microscopic fraction of observables (ie, systems that happen to have their ecliptic in line with ours, and have an orbital period so far of 1 year) and base broad, sweeping conclusions about the entire universe on them.

    These guys are almost as bad as anthropologists, who'll build an entire career 'interpreting' facets of a who civilization extrapolated from a half-dozen potsherds.

  • Free ArXiv version (Score:3, Informative)

    by amaurea ( 2900163 ) on Friday May 03, 2013 @07:54AM (#43619087) Homepage

    The actual article is much better than the one linked in the story. A version very close to the one published in Science can be found here [], at the public preprint archive (arXiv). The article should be relatively easy to read even for non-scientists. Note that our knowledge of the distribution of planets is marred by the biased sample we have access to: It is much easier to observe planets if they are close to their parent star, and heavy. Most of the statistics provided in the article attempts to correct for this bias, so we can say pretty confidently that small planets are much more common than large ones*. But the other claim in the summary, that most planetary systems are much more compact than the solar system, doesn't seem to be supported in the article itself. But perhaps I missed something.

    Anyway, the Science article is readable, and if nothing else the figures are quite interesting.

  • Isn't there something to be said for sample size here? We've had the ability to "easily" see large planets. We've discovered that there is a strange(to us) phenomena known as "Hot Jupiter". But other than that, we have found only relatively large planets up to this point. Each of those systems with large planets may also contain smaller planets as well.

    You can't prove a negative, but that appears to be what they are doing. Since we don't have the tech to discover systems like our own, we MUST be rar

    • Re: (Score:3, Insightful)

      by amaurea ( 2900163 )

      You and a whole horde of other slashdotters have had the idea of ease-of-measurement bias - a large fraction of the posts on this article mention it. Thankfully, the researchers who study these planets have also thought of it. They have even measured how large it is, and corrected for it. One result of this is that even though we see a large number of hot jupiters, we know know that planets get more common the smaller they are. That is actually one of the main points of the article. I guess this goes to sho

  • I cant believe Seager and Howard dont know this. I think the journalist must mistinerpreted their paper.
  • Observation (Score:4, Insightful)

    by DarthVain ( 724186 ) on Friday May 03, 2013 @12:20PM (#43621931)

    Well until we actually observe other alien life the scientific assumption should be that most life is like ours, that ours is the path of least resistance, the optimal path that all life takes. I think we should be open to it being radically different, however until we observe anything to the contrary, it is all just so much speculation. It could be that some life is so radically different that we may have a hard time recognizing to even observe it. It could be that we are the life oddballs, and most take another path. Who knows. However at this time the most rational response would be to surmise that at least at this time, life is likely similar to ourselves.

The truth of a proposition has nothing to do with its credibility. And vice versa.