Better to state that the position of the stars when you were born is not material to defining your personality. Because that’s what the mainstream astrology claims.
What do I know? I work for a bunch of astrologers, er, astronomers.
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It doesn’t make any sense to me, and since it gets complained about a lot, I’m going to indulge myself and explain why. I mean, you invited me to think about it, right?
It’s true planets span a wide range in size and mass, but all of the eight are well ahead of everything else, in a much more meaningful sense than being 1471 instead of 1445 miles across. Take any cut-off that’s based on a reasonable-sized gap in the distribution, and Pluto is not going to be on the larger side. But much more significant is that being a planet was never solely about size, but about place in the solar system.
Ganymede is much bigger than Pluto, but its position marks it out as a moon. Ceres turns out to be much smaller, but it was demoted long before its mass was known; the problem is that it was one of many. In fact nearly all of the objects in the solar system fall into one of these categories, either going around a much larger one or existing as part of a belt of many objects of varying size and generally overlapping orbits.
The few exceptions are some objects orders of magnitude larger than anything else that comes near them, in a relatively regular arrangement of near-circular orbits along with the more diffuse belts. In some sense they are each a belt of one plus comparatively insignificant debris. It happens that there are very unambiguously eight of these.
I’ll note the IAU definition was based on a formal measure of this, which gives a spectacularly bipartite distribution; these eight have indices above 10000, all the others less than 1. So it actually tells you something about the structure of the solar system, and in a way that one could fairly naturally compare to most of the exoplanet systems being discovered, though not all - the universe is a strange place. To the point where if there wasn’t the word “planet” for them, I think we would actually end up inventing another one.
There’s the logic, and if you want non-arbitrary, I’m not sure how you can do better. Having moons and atmospheres are definitely red herrings, if you count Mercury and Venus instead of Ida and Chiron. And again, for size there is a series of just-slightly-smaller objects all the way down from the larger moons; there are multiple large gaps, but none are below Pluto.
The only other suggestion I’ve seen is wanting a purely arbitrary size cut-off, just under whatever Pluto proves to be, because any attempt to reflect the nature of the outer solar system we’re discovering is less important than keeping things the way the baby boomers had them. That genuinely doesn’t seem sillier to you?
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That background looks familiar…nice wallpaper.
It will if you get too close to it (the sun) 
I grant that if it’s about location rather than physical attributes like mass, composition, etc. then the difference in terminology makes some sense. However, I submit that the only reason the IAU goes by this criteria is that the organization is dominated by people who study astronomy vs. people who study planetary geology.
If we were to reinvent the naming conventions completely with the knowledge we have today, I think it would make more logical sense to group all the gas giants orbiting a star as one category of object and all the (nearly) spherical rocky bodies orbiting a star as another category of object.
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I should point out spherical doesn’t mean as much as you credit. Ceres is round, but for slightly-smaller Vesta it’s a difficult call whether it’s irregular or mostly-round with unusually large craters. From both an astronomical and geological perspective, both are plainly akin to the smaller irregular asteroids; who does it help to class them with Mars instead?
That said, I think it could make sense to have groups for all the gas giants, the spherical rocky bodies, and the spherical icy bodies. But if that’s your interest, I think you are completely ruining their value by ignoring ones that don’t orbit the star. Triton is heated by Neptune, but it’s plainly an object from the same family as Orcus, Pluto, Charon, Haumea, Quaoar, Makemake, Eris, and Sedna. If you aren’t interested in location I can’t see why you’d separate them.
So while I’m all for a proper geological classification of objects out there, anything starting with planets and moons is a non-starter. They’re useful for discussing solar system structure and formation; they haven’t been for composition ever since the Moon and Io were split from the other round silicate bodies.
And historically, that’s at least not what you want to base your identifiers on, because you can figure out where something is with certainty long before you can be sure what it is; that applies less to our solar system now, but it’s going to apply to others, so I think it’s important to still have astronomical terms around.
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well, if you read it, once, somewhere, that actual studies (not faked studies) bore this out and invalidates science as we know it-- good enough for me (and you, apparently).
Yeah, but they split whatsoever into three words, so they know fuck all and can’t be trusted any more than the horoscope people.
All of these systems like astrology, tarot, candles, crystals, I Ching, religion, and etcetera have no predictive power. They are intended to be a small ritual that focuses your attention on the here and now, with maybe an emphasis on something going on in your life. A time to think about it, that’s all. The charlatans use these systems to cheat the gullible by invoking magic into them.
In the lower right corner of the poster it says FSM, so that’s a clue for where it came from.
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This here map aint gonna have no influence over my life, durn’t mean I’ma throwin’ it away neither.
When the local paper printed a horoscope for 2015, I was going to write in demanding equal time for augury, being just as accurate (think I left it too late, though).
a) One of my temp jobs out of college was working as a clerk at the Birmingham News. The paper printed the horoscope on their funnies page. The reporters told me that they liked to cut the whole section up (this was back when things were still somewhat physical with the layout process) and scramble the signs and their predictions.
b) As someone who has had some astrology done as well as tarot readings, it is an indulgence. Everyone likes to talk about themselves. Sometimes a talented reader can provide some insight that helps you to view your current situation a little differently. If you take it for the fun it is, it’s all good. If you live your life by it, you are being played by a con artist.
You must be an Aquarius 
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Well… then let astrologers make that claim.
Meanwhile I’ll make the claim that since actual effects are not known/proven, then, everything else being equal, they cannot have a practical effect on your life. At least not in the sense that you can obtain any information that can be of any advantage to you.
Let whoever wants to, look into it though.
Tea leaf reading is certainly in a different category than those other practices. By the time you’re done with the cup of tea, the alleged old gypsy woman knows if you want to hear more about the tall dark good-looking stranger, or about whether your lover is cheating on you, or whether you’ve got any money that’s easily taken.
(*Disclaimer - I did contribute to a joke that made its way into the Silicon Valley Tarot; see the Ace of Disks.)
If you’re defining a planet based on geology rather than orbital dynamics, then we already know of many dozens of planets, since there’s no reason to exclude Titan, Ganymede, Callisto, Europa, Nereid, our own Moon, and so on. A planet is a body orbiting the Sun that’s not closely linked with another larger body – the above-named moons are excluded because they’re satellites, and Pluto is excluded because it’s in an orbital resonance with Neptune – it’s like a satellite of Neptune, just with a looser association.
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