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Space Science

Astronomers Find Planet Barely Larger Than Earth's Moon 71

Posted by Soulskill from the that's-no-planet dept.
The Bad Astronomer writes "A team of astronomers has announced the discovery of the smallest exoplanet orbiting a Sun-like star yet found: Kepler-37b, which has a diameter of only 3865 kilometers — smaller than Mercury, and only a little bigger than our own Moon. It was found using the transit method; as it orbits its star, it periodically blocks a bit of the starlight, revealing its presence (abstract). Interestingly, the planet has been known for some time, but only new advances in asteroseismology (studying oscillations in the star itself) have allowed the star's size to be accurately found, which in turn yielded a far better determination of the planet's diminutive size. Also, the asteroseismology research was not funded by NASA, but instead crowd funded by a non-profit, which raised money by letting people adopt Kepler target stars."
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Astronomers Find Planet Barely Larger Than Earth's Moon More

Astronomers Find Planet Barely Larger Than Earth's Moon

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  • That's... (Score:2, Funny)

    by Ashenkase ( 2008188 )
    No moon!

  • Pretty amazing (Score:4, Interesting)

    by Grayhand ( 2610049 ) on Wednesday February 20, 2013 @04:51PM (#42958761)
    It wasn't that long ago the first planets were found and now they are detecting ones around the size of the Earth's Moon. Imaging Earth sized planets will be the big breakthrough. There's talk of imaging planets similar to space shots of the Earth and other planets but I have my doubts I'll live to see that. It's not the technology it's the investment that would need to be made. Humans walking on Mars and a detailed photo of a distant planet would be the two I hope to live to see.

  • A planet or a dwarf planet? (Score:4, Insightful)

    by maxwell demon ( 590494 ) on Wednesday February 20, 2013 @04:52PM (#42958765) Journal

    A planet or a dwarf planet?

    I mean, if Pluto is not allowed to be a planet, then why should such a small object be labelled as one?

    • I mean, if Pluto is not allowed to be a planet, then why should such a small object be labelled as one?

      Shhh ... people might hear you and think you're making sense.

      We can't have that.

      • Re:A planet or a dwarf planet? (Score:4, Insightful)

        by osu-neko ( 2604 ) on Wednesday February 20, 2013 @05:59PM (#42959577)

        I mean, if Pluto is not allowed to be a planet, then why should such a small object be labelled as one?

        Shhh ... people might hear you and think you're making sense.

        We can't have that.

        One would hope not. It's annoying when ignorant drivel is modded "insightful" here. Just because "people hear you and think you're making sense" doesn't mean you actually are...

        I have respect for people who think Pluto should still be considered a planet... assuming they also think Eris should be a planet, and long before Pluto was demoted, were upset about the fact that Ceres is not considered a planet. It's the knuckle-dragging morons who are upset about Pluto but never were bothered by Ceres not being a planet that need to get a freakin' clue. If you had no problem with Ceres not being considered a planet, you shouldn't have any problem with the fact that Pluto isn't, either.

    • Re:A planet or a dwarf planet? (Score:4, Informative)

      by Nadaka ( 224565 ) on Wednesday February 20, 2013 @04:59PM (#42958825)

      because the determining factor in excluding Pluto from the list of planets is not its size, it is that it has not cleared its orbit of other bodies.

      • Re: (Score:2)

        by mark-t ( 151149 )
        By that reasoning, neither has Neptune.

        • Re:A planet or a dwarf planet? (Score:5, Informative)

          by medcalf ( 68293 ) on Wednesday February 20, 2013 @05:12PM (#42958929) Homepage
          Not really. "Cleared its orbit" doesn't mean no co-orbital objects. All planets have LaGrange point co-orbitals for example. Pluto is different in that it has a lot of co-orbitals, and some of them are almost as large as Pluto itself. Essentially, it's a KBO rather than a planet proper, by the current definition.

          • Re:A planet or a dwarf planet? (Score:5, Informative)

            by Chris Burke ( 6130 ) on Wednesday February 20, 2013 @05:54PM (#42959517) Homepage

            Pluto is different in that it has a lot of co-orbitals, and some of them are almost as large as Pluto itself.

            To make it clear how big a difference it is, let's look at the ratio of the mass of the body in question to the mass of the rest of the objects in its orbit (discounting direct satellites).

            Of the planets Neptune happens to have the lowest such ratio. It outmasses everything else in its orbit by a factor of over 10,000.

            Meanwhile Pluto is outmassed by the other objects in its orbit by more than a factor of ten. It is less than 10% of the mass in its orbit.

            That's a five order of magnitude difference. "Clearing the orbit" isn't precisely defined... and it doesn't need to be. You don't need a precise definition of where exactly on the beach the ocean begins to know that Asia and North America are separated by the Pacific Ocean.

            And I suspect that such a large distinction isn't a cosmic accident, and that other star systems of sufficient age will show a similar trend. Unfortunately it's going to be a long time before we can test this hypothesis.

        • Re: (Score:2)

          by Nadaka ( 224565 )

          Neptune and Pluto have synchronized orbits with a stable resonance of 3/2. Pluto is effectively captured.

          • Re: (Score:2)

            by medcalf ( 68293 )
            Um, what? I think you misunderstand the significance of the stable resonance of Pluto's orbit with Neptune's. It's just a way of describing where Pluto is. What's important about that is how many other objects share that same orbit, and how large they are, not what the orbit is. (IIRC, the other objects are called Plutionoids, but I'm too lazy to Google and be sure.)

      • because the determining factor in excluding Pluto from the list of planets is not its size, it is that it has not cleared its orbit of other bodies.

        So, would that meteor that landed in Russia mean that Earth isn't a planet? Don't pretty much all of the planets run into other things pretty constantly?

        I've never fully understood why Pluto got demoted, and I'm not sure I do yet.

    • Re: (Score:2)

      by zmooc ( 33175 )

      In order for it to be a dwarf planet, it must be in our solar system; apparently dwarf planets are defined as "celestial bodies in direct orbit of the Sun."

      Furthermore, the major difference between a planet and a dwarf planet is that the former must have cleared its orbital region of other objects. Obviously we cannot know for sure whether that is the case for this celestial body. Therefore this may very well not be a planet either!

    • These are simply exoplanets. No formal definition exists dividing them into further categories. There is still debate over where planets end and brown dwarfs begin, let alone the smaller end of things. As of 2006, when the definitions for planet and dwarf planet were created, we knew almost nothing about planets outside of our solar system. Trying to figure out how to categorize them at that point would have been putting the cart before the horse (although that didn't stop some people [wikipedia.org]). But there was no rea

    • Re:A planet or a dwarf planet? (Score:5, Interesting)

      by mrtommyb ( 1534795 ) on Wednesday February 20, 2013 @05:30PM (#42959135)
      Hi, I wrote this paper: We actually looked very carefully whether this planet has cleared its neighborhood. The smallest reasonable mass we can assume for this planet is 0.01 Earth masses. With this mass it would clear its orbit of other bodies. However, if it were much further away from its star (like at the distance Pluto is from the Sun) then it would probably be considered a dwarf planet.

    • Thank you for saying that!

      I was thinking the same thing.

    • Pluto is smaller then our moon, this one is just slightly larger...while i admit that the thought crossed my mind at first, and it certainty posses the WTF do we do about this kind of question, Pluto does things that other planets do not do, like the crazy orbit and crossing in the orbit of another planet. Pluto is not a planet and it cannot be categorized as one for a variety of reasons, not just its size, but the way it acts and also its formation. Its simply the way science categorizes things that makes

    • Re: (Score:1)

      by tbid18 ( 2495686 )

      A planet or a dwarf planet?

      I mean, if Pluto is not allowed to be a planet, then why should such a small object be labelled as one?

      The defining characteristics of a planet are:

      (1) Large enough for gravity to make it round.

      (2) "Dominates" its orbit.

      Pluto fails (2) because it's a Kuiper Belt Object and there are many other KBO's in its orbit. It's not gravitationally powerful enough to eject or capture them. This may seem arbitrary because pluto would be considered a planet simply if there weren't any other objects in its orbit, but that's the current definition.

  • enhermesenate? (Score:4, Funny)

    by jdastrup ( 1075795 ) on Wednesday February 20, 2013 @04:53PM (#42958781)
    Below the caption of the artist's rendition: "Click to enhermesenate"

    New word for the day

  • Being able to find smaller things far away is good.

    While there is high hope of finding Life elsewhere is slim to none, at least it gives us better places to look and send out messages too.

  • If it has been known to be around "for some time" then I don't understand why they are calling it a new discovery- it's more like their decision to formalize their acknowledgement of its existence to the public.
    • What they've known some time is "there's a planet there." Recent developments resulted in "Hey! That planet's REALLY small!"

    • A team of astronomers has announced the discovery of the smallest exoplanet orbiting a Sun-like star yet found

      It's not the existence of the planet that they are announcing:

      the planet has been known for some time, but only new advances in asteroseismology (studying oscillations in the star itself) have allowed the star's size to be accurately found, which in turn yielded a far better determination of the planet's diminutive size.

      The new measurement now means the exoplanet is the smallest on record.

  • If it is only a bit bigger than the moon then it wouldn't seem to qualify as a planet, only a planetoid.

    • Incorrect conclusion there. Size is not the sole determining factor. Pluto was demoted (for want of a better word), because it had not cleared out it's orbit of of other significant bodies. Ie. there's a shit-load of stuff that shares the same orbit as Pluto and some of that stuff is larger than Pluto.

      • Re: (Score:1)

        by osu-neko ( 2604 )
        Right. Ceres is even smaller, but would be considered a planet if it weren't for all the other stuff in its orbit. In fact, it was considered a planet for a while, but got demoted after more and more stuff started showing up in what is now called the Asteroid Belt.

  • Asteroseismology? (Score:3)

    by Antipater ( 2053064 ) on Wednesday February 20, 2013 @05:17PM (#42958973)
    This term struck me as odd. The side of me that cares about meaningless pedantry wants to know why it's "asteroseismology" and not "astroseismology", but Google isn't helping much. Anyone happen to know?

  • Pluto me once, shame on you. Pluto me twice, shame on me.

    • Re: (Score:1)

      by Anonymous Coward

      No, lemme help ya out there:

      pluto me once, pluto on — pluto on you. Pluto me — you can't get plutoed again

  • how many more.. (Score:1)

    by Anonymous Coward

    ..of the "Oh Shit" we found a rock in space moments are we gonna have. Notify me when we are going to Titan pls.

  • Wouldn't that really be the largest exoplutoid found?

  • We are now finding new planets, what next, habitable planets, inhabited planets? We can make 3 D doodling pens and yet, all we have for our taxes is crappy cars with even crappier gas mileage. What's worse is all the crappy auto execs with not so crappy bonuses.

  • It's an exoplanet-sized object.

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