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."
Sun is the same way (Score:5, Informative)
The barycenter of the Sun/Jupiter system lies at 1.07 solar radii from the Sun's core (i.e. outside the Sun). Is the Sun a binary star?
For those curious, the barycenter of the Earth/Moon system is well inside the Earth, despite the Moon relatively energetic orbit.
Barycenter based definition has issues (Score:5, Informative)
Re:Sun is the same way (Score:3, Informative)
Well, it does radiate more energy than it gets from the Sun...
Re:Sun is the same way (Score:5, Informative)
If the mass part counts at all (Charon being 12% of Pluto's mass), Jupiter is a far smaller fraction of the Sun's mass (something like 0.1% if I did the math right).
No (Score:4, Informative)
Because Pluto is not a planet.
Binary dwarf planets, sure. That seems a reasonable argument. But even treating Pluto and Charon as a single entity can't upgrade them to planet status.
Re:Pluto never was a planet (Score:5, Informative)
"Is it something more personal between individuals in astronomy?"
This, actually. Long story short, there are two camps of astronomers. One of them characterizes bodies based on where they're orbiting, the other characterizes bodies based off what they're made of.
The former pushed this through as an act of political dickmanship on the last day of a conference (after most participants had gone home), in a only tangentially related addition to a talk scheduled for a different topic, breaking IAU rules to do so. It's not a 'scientific' decision, it's a purely political one.
And any definition that has a category 'dwarf planet' that isn't a subset of 'planet' is about as stupid as redefining 'car' so that 'electric cars' are no longer a subset of 'cars'.
Re:Now it makes sense (Score:5, Informative)
Re:IAU? Haste? No way. (Score:5, Informative)
Why do you call the committee members pseudo-scientists? I'm rather sure everyone has a PhD in astronomy/astrophysics. (I'm technically an IAU member, although I've had little involvement with it.)
They don't experiment. They don't work in a lab. They may be involved in the scientific community, but they're not doing any scientific work per-se. They're bureaucrats with training in science.
Can you specify some names so I can check this is really true?
(Not many of us astronomers work in labs or experiment anyway. We mainly obtain and analyze data, construct theoretical models. A smaller number of us work on instrumentation which might involve working in an actual lab.)
Re:IAU? Haste? No way. (Score:5, Informative)
It would be virtually impossible to name names. The reclassification of Pluto (among other things) was the result of a vote held at the end an IAU General Assembly where only 424 out of roughly 9000 members actually voted [wikipedia.org].
Re:IAU? Haste? No way. (Score:5, Informative)
The IAU, both committee and members, is made up of active scientists who do the bureaucratic stuff in addition to their research jobs. That is how professional organizations usually work, the people running them are doing community duty above and beyond their paid employment.
Re:IAU? Haste? No way. (Score:5, Informative)
Actually working astronomers do a lot of lab work. They do spend a good bit of time refining theoretical models, but a lot more time working out ways to test those models with existing laboratory equipment. Some of that equipment is now in orbit and much of the remainder is in "observatories". You know, research laboratories with telescopes instead of microscopes.
Astronomers are also a very resourceful bunch who are continually looking for ways to test their theories against laboratory observations that have already been done. If you can find what you need to test a hypothesis in last year's download of Hubble material, or the digitized images of telescopic photos taken in the 1930s, that still counts as laboratory research.
Re:Pluto never was a planet (Score:2, Informative)
It's even weirder when you consider that even now, the IAU agrees that Pluto is a dwarf planet. It's just that their change was to make it so that a dwarf planet is not called a planet. It's a very, very odd linguistic or logical choice to make and yet you can find information online about some of the rather severe political tactics used to ensure the change was made.
Re:Sun is the same way (Score:3, Informative)
Some people also consider the Earth/Moon to be a binary planet. The Sun's hold on the moon is actually greater than the Earth's, and so if you were looking at the Moon's path in the solar system it is always concave to the Sun. The path of any other moon in the solar system is sort of zigzaggy, sometimes moving towards the Sun and sometimes away, depending on its location relative to its planet.
Wikipedia probably explains it better: http://en.wikipedia.org/wiki/Double_planet
http://en.wikipedia.org/wiki/Orbit_of_the_Moon#Path_of_Earth_and_Moon_around_Sun
Re:IAU? Haste? No way. (Score:5, Informative)
Re:IAU? Haste? No way. (Score:3, Informative)
Most do not view holy books as literal truth like religious fundamentalists, but rather guidelines and proverbs on the meaning behind life and how to live it well. Nor do they believe in creationism and other pseudoscience. But there are a large number of chemists, biologists, virologists, toxicologists, medical doctors, etc. that go to church, temple, mosque, etc.
Re:IAU? Haste? No way. (Score:2, Informative)