Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
Space Science

Is Pluto a Binary Planet? 275

astroengine writes "If the Pluto-Charon system were viewed in a similar way to binary stars and binary asteroids, Pluto would become a Pluto-Charon binary planet. After all, Charon is 12% the mass of Pluto, causing the duo to orbit a barycenter that is located above Pluto's surface. Sadly, in the IAU's haste to define what a planet is in 2006, they missed a golden opportunity to define the planetary binary. Interestingly, if Pluto was a binary planet, last week's discovery of a fifth Plutonian moon would have in fact been the binary's fourth moon to be discovered by Hubble — under the binary definition, Charon wouldn't be classified as a moon at all."
This discussion has been archived. No new comments can be posted.

Is Pluto a Binary Planet?

Comments Filter:
  • by girlintraining ( 1395911 ) on Sunday July 15, 2012 @06:05PM (#40658519)

    The IAU has been trying to redefine things in bulk, and then growing discontent with those definitions and changing them yet again. It's a far cry from the organization's original role: Cataloging astronomical objects. To put it in perspective, they're like a librarian that changes the layout of the indexing system weekly. They don't actually move the books around, but they rename the aisles, recategorize things, and generally make a massive mess of it all.

    But then, I'd expect nothing less from a committee of pseudo-scientists; They're so engrossed with their own administrations they've become cut off from the people they're supposed to be helping.

  • by TheGoodNamesWereGone ( 1844118 ) on Sunday July 15, 2012 @06:28PM (#40658653)
    I do not understand at all the rage over Pluto's demotion from planetary status. Is it tradition? 'Traditionally' the Sun was thought to revolve around the Earth. Is it because children have to be sat down and gently told the truth, like about Santa Claus? Is it something more personal between individuals in astronomy? It's called *science* folks, and it's self-correcting. I just don't get why people are so upset.
  • by Tim the Gecko ( 745081 ) on Sunday July 15, 2012 @08:51PM (#40659441)

    No, it's a hallmark of the bored with too much free time. If you had an employee who spent most of their time recategorizing rather than coming up with something new, would you consider them intelligent? You'd probably think they were lazy or incompetent.

    The implication here is that people just got bored and changed things, but really it's just like the planet-to-asteroid naming change in the 1800s. People find a new planet (Ceres/Pluto), and after a while find a whole lot of similar objects. You probably don't want to learn a whole lot of asteroid or KBO names.

    Added to this, our notions of Pluto have gradually dwindled from a huge pitch-dark planet, able to perturb the mighty Neptune in its orbit, down to a small bright billiard ball with a gravitational pull only slightly bigger than that of yo' mama.

  • by arth1 ( 260657 ) on Sunday July 15, 2012 @09:13PM (#40659545) Homepage Journal

    ... since the orbit of Pluto crosses that of Neptune and therefore Neptune has not cleared out its region of space yet, and probably never will.

    No, the orbit of Pluto never crosses that of Neptune. Really. Sometimes Pluto is closer to the sun than Neputune is, but the two orbits never cross. You have to think in 3D here.

    But "clearing the orbit" is a stupid argument, nevertheless. By that measure, we have one planet in the solar system, and that's Mercury. All the others have various debris floating around in their orbits, especially near the Lagrange points 30 degrees ahead of and behind them.
    And Mars wouldn't compete for a planetary title at all - its orbit is mostly clear because of Jupiter and Earth, not itself - it's just too small to keep its orbit clear on its own.

    I think the actual reasoning behind demoting Pluto is that a camp of astronomers want a fixed number. So you take the classic planets known since the antique, and add Uranus and Neptune because they're too friggin' big to be ignored, and leave it at that. Then you make up rules that would pass your eight and block any others.

  • by Will.Woodhull ( 1038600 ) <wwoodhull@gmail.com> on Sunday July 15, 2012 @09:58PM (#40659751) Homepage Journal

    As far as I know, the question of whether Jupiter is producing energy through some core fusion or fission process remains unresolved. Jupiter might well be reclassified as not a planet, but as a dwarf brown star.

    So perhaps we are in a binary star system.

    Furthermore, the Earth's orbit is so strongly perturbed by the Moon that the time of perihelion shifts over more than 24 hours from year to year, depending on where the Moon is in its orbit on Jan 3 through 5. This is an angular variance of about 1 degree, which would be obvious to any outside observer capable of resolving the Earth, Venus, and Mars. They would almost certainly list the Earth - Moon pair as a binary planet.

    So perhaps we are on a binary planet in a binary star system. It pretty much all depends on how you look at it. And science progresses when a large number of different models are all considered. It does not progress when the IAU attempts to shove one particular model, and one that has not been very well constructed, into everybody's head.

    Spirit of Galileo, save us from those astronomers who have been educated beyond their level of intelligence.

  • by chebucto ( 992517 ) on Sunday July 15, 2012 @10:46PM (#40659965) Homepage

    true genius is making things simpler.

    Or rather, true genius is making things as simple as they can be but no simpler.

    Speaking as an amateur, it seems that adding the 'minor planet' category was a reasonable decision. Charon & Pluto are distinct from asteroids, but quite a lot smaller than the rest of the bodies we call planets.

    In other fields, we distinguish between islets and islands, streams and rivers, bushes and trees, etc etc etc. Not to add complexity, but to more fully describe reality.

  • by Anonymous Coward on Monday July 16, 2012 @04:03AM (#40661013)

    Working astronomer here (radio, ground-based). I spend about 2-3 weeks per year actually at an observatory. That's roughly typical in this field, though there's a lot of variation: some people work more on the engineering side and spend 90% of their time on-site, while pure theoreticians might never see a telescope.

The unfacts, did we have them, are too imprecisely few to warrant our certitude.