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Can We Call Pluto and Charon a 'Binary Planet' Yet?
astroengine writes The debate as to whether Pluto is a planet or a dwarf planet rumbles on, but in a new animation of the small world, one can't help but imagine another definition for Pluto. As NASA's New Horizons spacecraft continues its epic journey into the outer solar system, its Kuiper Belt target is becoming brighter and more defined. Seen through the mission's Long Range Reconnaissance Imager (LORRI) camera, this new set of observations clearly shows Pluto and its biggest moon Charon locked in a tight orbital dance separated by only 11,200 miles. (Compared with the Earth-moon orbital separation of around 240,000 miles, you can see how compact the Pluto-Charon system really is.) Both bodies are shown to be orbiting a common point — the "barycenter" is located well above Pluto's surface prompting a new debate on whether or not Pluto and Charon should be redefined as a "binary planet".
You're just trying to troll Neil Tyson for the hilarity that ensues.
seriously....call Pluto what it is...ClickBait.
We should launch an expedition to reactivate the Charon mass relay.
What's with this "dwarf" nonsense — and big planetarism? We demand equal gravity for all planets!
In Soviet Washington the swamp drains you.
I can't believe that this is still an issue. Guess what? IT DOESN'T FUCKING MATTER! This sort of pathetic taxonomic squabble is pointless, and just takes time and attention away from investigating real astronomical phenomenon and making real discoveries.
It's like those people who claim that JavaScript is a good programming language. There's nothing to debate. JavaScript is total, indisputable shit. It's a pointless argument to get into, because those claiming that JavaScript is good have already lost.
Astronomers and other scientists, please focus on furthering our knowledge of the universe. Don't waste time with stupid arguments over irrelevant issues like this.
The Earth-Moon barycenter is very nearly outside of Earth itself (it's about 0.75 Earth radii from Earth's center), so let's not get too high on our horses...
The arguments for demoting Pluto from its planetary status still holds. And hardly anyone objects to Pluto and Charon together as a binary system. But this "new" insight does not promote Pluto/Charon to planetary status. Binary dwarf planet, binary kuiper belt object, binary plutoid. Absolutely. Binary planet? No.
- Henrik
- when the Shadows descend -
Pluto is a planet. The definition of a planet is arbitrary, and always will be.
Trying to forcefully change the definition after it's already in use is fucking retarded and does nothing but cause confusion.
For other instances of dipshits trying to hijack language and make it worse, see "non-flammable" and the dipshits who insist that a kilobyte is 1000 bytes.
Planet and Dwarf Planet are arbitrary labels defined by the IAU.
How can you "debate" about that?
sic transit gloria mundi
This mission will put a new spotlight on Pluto and its âoedwarf planetâ status, potentially highlighting its current classification as a woefully inadequate description of such a dynamic and interesting binary system.
Ok, so it's a "binary dwarf planet" - can we tone down the prose now?
sic transit gloria mundi
I have binary testicles!
Pluto is a dog planet.
Can everyone please just LEAVE PLUTO ALONE.
The barycenter of the Sun and Jupiter is above the surface of the sun, does that mean we'd have to reclassify our solar system as a binary star system now? http://spaceplace.nasa.gov/bar...
Unless Pluto (and Charon) shifted orbit into the planetary plane, nothing has changed and any desire to call it a planet is just sentimentality.
what the 'A' in NASA stands for...
Pluto doesn't care what you call it. It's going to be around when you are dust in the wind. Oh and I don't care either.
Mean what you say...say what you mean.
what is that? Why not furlongs or Manhattans?
Earth/Luna is a binary planet by the criteria.
It's not. The center of gravity is under Earth's surface.
Most significantly, Luna's orbit is never convex with respect to the Sun.
The Moon's orbit is convex.
No phone lines yet. Sorry.
" Pluto and Charon are sometimes referred to as a double dwarf planet system."
No.
I suppor tthe right of the people of Pluto to decide their own destiny, and not be ruled by any arbitrary group of people on some other planet.
Freedom for the Plutocrats
Out of all the people who bitch and complain about Pluto, how many will even pretend to care when New Horizons gets there next year?
Pluto is not a planet, nor is the Pluto-Charon system a double planet. Being a cluster of Kuiper belt objects, the Pluto system is a Kuiper Cluster.
Uh, folks, Pluto actually has FOUR moons... Charon: Discovered in 1978, this small moon is almost half the size of Pluto. ...
Nix and Hydra: These small moons were found in 2005 by a Hubble Space Telescope team studying the Pluto system.
Kerberos: Discovered in 2011, this tiny moon is located between the orbits of Nix and Hydra. ...and it just keeps on thumbing it nose at the dwarfists, and now, the binarists.
But tell me, how is a FIVE body system a BINARY system? Hmmmmm?
My mistake...Pluto has FIVE moons. Charon: Discovered in 1978, this small moon is almost half the size of Pluto. It is so big Pluto and Charon are sometimes referred to as a double planet system. Nix and Hydra: These small moons were found in 2005 by a Hubble Space Telescope team studying the Pluto system. Kerberos: Discovered in 2011, this tiny moon is located between the orbits of Nix and Hydra. Styx: Discovered in 2012, this little moon was found by a team of scientists search for potential hazards to the New Horizons spacecraft flyby in 2015. may the 'little planet that could' keep right on thumbing it nose at everybody!
The earth and moon do the same dance but with a different mass ratio. Students just get pointed off track when the discussion turns from physics to human nomenclature.
Well, Earth has an unmanned expeditionary mission that will take pictures of Charon in July 2015 =^-^=
"Screw Sun, cross-platform will never work. Let's move on and steal the Java language." - Visual J++ Product Manager
The answer is simple - that Lagrange point is not stable, so the moon would not remain there. Each moon would be pulled from that point by the other's gravity, until they either collide or one or both items are thrown from their orbits.
So as a planet cannot have two moons that orbit opposite each other, the concept of a binary planet with a definition based on the location of its barycenter is valid. But we'd first want to see one - Pluto/Charon is a poor example, as Pluto is considerably larger and heavier than Charon, so 'Planet/moon system' defines it better. If we start to find real binary planet systems outside of our solar system and stat characterizing them, then we will be able to know what sorts of systems happen and how they form, and maybe then we will find that Pluto/Charon belongs as an outlier there. But that's for a future time.
Prediction for end of Universe #42: Fencepost error in Quantum_bogosort.cpp
"They invented a reason,
That's why it stings,
They don't think that you matter,
Because you don't have pretty rings."
-Jonathan Coulton
Agreed, that one is a bit far fetched. It's a many-body problem and all it takes is a bit of eccentricity or pull from other moons, planets, and the sun to destabilize.
But back to the first question, what if the barycenter moves in and out of the planet due to multiple moons? This would be akin to the solar system, where the barycenter moves in and out of the sun. I don't know if we could easily call it a ternary planet, quaternary planet, etc.
I think I prefer Isaac Asimov's tug-of-war definition of a binary planet. It would be considered a binary planet if the smaller body has a concave orbit around the sun; in other words, the two are both primarily orbiting the sun and just happen to be close to each other. This would, however, define the earth/moon system as a binary planet and Pluto/Charon would be a planet/moon.
All my liberal friends think I'm a conservative, all my conservative friends think I'm a liberal.
Another reason I don't care for the barycentric approach is because it depends so highly on the radius of the larger body. What if the barycenter of the moon were right above the surface but well within the atmosphere? What about a gas giant where the definition of the radius is a bit fuzzier?
All my liberal friends think I'm a conservative, all my conservative friends think I'm a liberal.
Again, I would have to be convinced that a group containing more than two objects with sizes within an order of magnitude of each other would be stable. Myself, I can't see it. Two large moons would push each other into chaotic orbits which would, sooner rather than later, lead to either a collision or an ejection.
The only way I can see a system with two large moons is with a planet that is completely dominant, such as Saturn or Jupiter and it's moons. (I'd argue, for instance, that Earth could not have held on to two moons.)
But these questions can really only be answered when we have more binary-planet candidates to categorize.
Prediction for end of Universe #42: Fencepost error in Quantum_bogosort.cpp
Barycenter not closer to either planet than a chosen percentage of the distance between their centers would be better.
Prediction for end of Universe #42: Fencepost error in Quantum_bogosort.cpp
We've known for at least a decade now that Pluto/Charon's barycenter is outside the mass of Pluto. That was one of many arguments used to delist Pluto from the Solar System planets. Those same "Pluto is a planet" fossils probably would demand Ceres be restored to planetary status, if they lived two hundred years ago.
There is no America. There is no democracy. There is only IBM and AT&T and DuPont, Dow, General Electric, and Exxon
That definition would reduce the problem to the relationship of their masses.
All my liberal friends think I'm a conservative, all my conservative friends think I'm a liberal.
I was thinking of this thread again (the tug-of-war definition) and thought of another interesting thing to calculate: What if I swap Pluto and Charon in the equation? Would it indicate that Pluto is also more influenced by Charon than the sun at times?
The answer is yes, meaning Pluto does not have a concave orbit either. The tug-of-war value focusing on Pluto as the primary body is 337.3 at perihelion, but focusing on Charon as the primary body it is 39.3. Since both are greater than 1, this means Pluto and Charon cause each other to have an occasionally convex orbit.
So perhaps this definition would still find Pluto/Charon to be a binary planet, but in a different way than the Earth/Moon are. Compare the numbers above with Earth/Moon: Earth-centric has a value of 0.45, Moon-centric has a value of 0.006. Both being less than 1, Earth and Moon always have concave orbits around the sun.
All my liberal friends think I'm a conservative, all my conservative friends think I'm a liberal.