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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.
What's with this "dwarf" nonsense — and big planetarism? We demand equal gravity for all planets!
In Soviet Washington the swamp drains you.
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 -
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
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...
the best question:
The moon is currently 239,000 miles away, and the barycenter is at 0.75 Earth radii from Earth's center. If the barycenter was at the earth's surface, how close would the moon be?
For the purpose of this calculation assume the earth is a uniform sphere with a mass of 5.97x10^24 kg and a diameter of the earth is 7,900 miles, and the moon is a uniform sphere with a mass of 0.0123 earths and a diameter of 2,160 miles.
BTW, I actually did the full calculations and accounted for the radius of earth/moon in the distance. But according to the equation for calculating barycentric coordinates, the distance of the barycenter from the center of the primary is linearly proportional to the distance of the centers of mass of the two bodies... so a pretty close estimate would have been (1 / 0.75) * 239,000 miles.
All my liberal friends think I'm a conservative, all my conservative friends think I'm a liberal.
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.
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!
Interestingly, Jupiter is the only planet which has it's barycenter with the sun outside of the sun.
The definition of whether something orbits something else, or whether it is a binary system is pretty arbitrary. It would be nice and neat if we could say that if the barycenter is inside the larger body, the smaller body is orbiting the larger, but that would mean that Jupiter would not be orbiting the sun.