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One Astronomer's Quest To Reinstate Pluto As a Planet
sarahnaomi writes: Most of us grew up believing that tiny, distant Pluto was the outermost planet in our solar system. Then, one day, the scientific powers that be decreed that it wasn't. But it seems the matter is far from settled. David Weintraub—who describes Pluto's exile as a stunt organized by a "very small clique of Pluto-haters"—would have the dwarf world rejoin the ranks of our Solar System's fully-fledged planets today. But solid evidence that Pluto deserves the title may come in July, when NASA's New Horizons spacecraft slingshots around the icy rock and sends us back a detailed picture of its composition. Pluto's planethood was revoked by majority vote on the final day of the 2006 IAU conference. Over 2,500 astronomers attended the meeting throughout the week, but only 394 votes ultimately decided Pluto's fate: 237 in favor of demoting the planet and 157 against.
This is stupid. When the IAU conference redefined Pluto, they didn't "demote" it, they simply reclassified it to more accurately suit it.
By any definition, it's either the 8 we have now, or 10 or 11. That's what started the Pluto mess, we discovered things bigger than Pluto way far out.
Don't make it sound so sinister. The vote wasn't to demote Pluto. It was a vote to settle on the criteria an astronomical body must meet in order to be a planet. This was necessary because we've found more Pluto like bodies, and chances are we'll find more in the decades to follow.
How many exoplanets pass the current IAU definition of 'planet'? I bet a bunch don't.
I would bet that every single one of them does. Current exoplanet detection techniques are only sensitive to the big ones in close orbits. To detect something as small as Pluto, in a distant orbit in which it might not have cleared its orbital zone of debris (and so not be a planet, by the IAU definition), is well beyond our current capabilities.
Exactly. There are many categories of planets, including but not limited to:
* Terrestrial planets
* Gas giants
* Ice giants
* Hot jupiters
* Superearths
And so forth. Why does the concept of another category, dwarfs, enrage people?
Really, the only categorization issue that I'm adamant about is that Pluto-Charon is called a binary. The Pluto-Charon barycentre is not inside Pluto, therefore Charon is not rotating around Pluto, the two are corotating around a common point of space between them. That's a binary.
You know when it's okay to shout fire in a crowded theatre? When it's on fire.
How dare you challenge the might of Jupiter! It weighs 320 times the mass of Earth -- even if those 100,000 trojan asteroids weighed as much as its minor moons (which they don't, they are 0.0001 Earth masses according to wikipedia), it would still dominate its gravitational field by several (9) orders of magnitude.
Compare that to Pluto: Charon already weighs 10% of Plutos mass. The center of rotation in that system is not even inside Pluto.
Also, there are other criteria that apply: a planet has to be spherical due to gravitation (there is a more technical definition). Is that the case for Pluto?
Finally, you can not have 9 planets anymore. You can choose between 8 planets and 13 planets, the latter group growing every year.
NB: The message above might reflect my opinion right now, but not necessarily tomorrow or next year.
As far as I'm concerned, if it's gravitation is enough to pull it into a sphere, it's a planet. Yes, I'm happy counting Luna and a bunch of other satellites
Then wouldn't our very own moon be a planet and not a moon by that definition?
Most people are ignorant that Earth's moon has a proper name: Luna, or that the term satellites refers to anything that orbits another body. Man-made satellites have recently become the primary definition of satellite but the original definition is still very much valid.
Another interesting fact: Earth's sun's proper name is Sol.
Even people in science careers are not immune to significant irrationality (I know, hardly Earth-shattering news).
When my grandmother was young, there were only eight planets, plus a few largish asteroids, then someone discovered another. As our instruments improved, we found many, many more "wanderers". We also learned how how their composition varied, and that there were more-descriptive categories to apply to the various bodies not only in this stellar system, but others.
It is utterly irrational to continue to collect Pluto into the same category as the eight other major rocky/gassy/icy Sol-orbiting bodies (the traditional "planets"), and NOT include the dozens of KBOs, TNOs, etc. that also orbit Sol https://en.wikipedia.org/wiki/Portal:Solar_System.
I before E except after C.
What a weird and foreign rule, with so many exceptions from the exception. A scietifically-minded species such as ours should have been sufficiently intelligent to create a more efficient spelling system than this. Let's just hope that future generations seize the opportunity to get rid of this ancient and inefficient spelling rule.
That's the thing. This definition includes Pluto but it also includes Ceres, the largest asteroid. It also includes Eris (of course since Eris is even larger than Pluto, any definition of a planet that includes Pluto must also include Eris). And it includes at least six to eight Kuiper Belt objects like Quaoar (the scrabble world whose name I've almost certainly misspelled). Plus a couple of scattered disk objects like Sedna which seem to just be out there in weir, random-looking orbits would also have to be included.
And this list would only grow as better telescopes and better survey techniques are developed. Here I think is the real reason that Pluto was demoted. Because it's easier to take it off of the list of planets than to include dozens of small, icy worlds.
Does this