Heaven forfend we ever find a Klemperer rosette. Even with members the size of Jupiter, we’d have to call the members asteroids, or plutons, or some such nonsense.
For all the fundies out there, here is something to throw out when people claim your position was carved out by majority opinion and not hard facts/revelation.
What a terrible example of science.
It’s a definition. What else are they supposed to do?
Look at the data on spacial bodies and examine where distinctions can be drawn. Yelling and lobbying should not be a part of the process.
This is my favorite “explanation” for the fact that all the “12 Colonies” of the Reimagined Battlestar Galactica universe appear to orbit the same star. As habitable zones tend to be narrow, some multi-body configuration about a narrow orbital range from the colonies’ star seems the only scenario allowed. The rosette is the prettiest.
It does seem a little implausible, though. What’s perhaps more plausible is what would have been called “double-planets” with both members far larger than Pluto, perhaps even gas giant size, orbiting other stars. Given the bizarre tilt of Uranus, it’s likely the product of the collision of two extremely massive bodies, and the orbital dance of those two protoplanets prior to the crackup would have confounded the proposed definition of “planet” and “dwarf”, I’m sure, if observed from afar.
This definition strikes me as the product of a poor compromise that results in yet more parochialism, the very thing they should have avoided.
Well, according to CNN, it looks like we’re down to 8 planets instead of being up to 12. Pluto got demoted.
Here’s a very short AP story about it. I feel a little bad for Pluto, or rather, for Pluto fans. But I thought the last definition was weak - it seemed to me that they were bending over backward to find a way to please the public and keep Pluto. I think this way is better.
“Dwarf” compared to what? Mercury? There’s not a hint of consideration of extrasolar planets here, or extrasolar planetary systems, or how the bodies, from tiny to titanic, we are bound to discover, will fit into this scheme. If this is all they’ve got, I think it stinks on ice.
So according to that article, Pluto doesn’t get planetary status because it hasn’t cleared the neighborhood of its orbit, as its orbit overlaps Neptune’s. I don’t quite see how this isn’t a symmetric definition. Doesn’t this also mean that Neptune hasn’t cleared the neighborhood of its orbit?
I guess it’s that it’s not “dominant”, but what if Pluto were, say, the size of Mars? Or Earth? Or Neptune?
Like I said, what we know as Uranus today is the product of a collision of two bodies that easily exceeded the mass of Earth, and for a time they must have co-orbited the Sun in some intimate configuration. Likely this went on for millions of years before they finally came into contact. If an astronomer tomorrow sees something like this thousands of light years away, what will he call it? Probably a double-planet, but the criterion, if I understand this all correctly, is “bigness”. They’d be way bigger than pluto, co-orbiting about a barycenter well outside the visible surface (whatever a “surface” is) of either body, and one would be almost certainly bigger than the other. So why should the smaller one be called a “planet”, using the criterion that effectively demoted Pluto? Answer: It shouldn’t. So what is it? A satellite? Not really. A “dwarf”? Well, what if it’s much larger than other technically-identifiable planets in its solar system?
Like I said, crap definition, if you ask me.
- It’s the new 12.
Oddly, exactly 200 years ago astronomers believed that there were 10 planets. But they didn’t include Neptune: the most recenly discovered “planets” were Uranus, Ceres (1801), Pallas (1802) and Juno (1804). Neptune wasn’t discovered until 1846, at which time only 5 asteroids had been discovered, and so it would be reasonable to say then that the solar system has 13 planets. However, in the 1850s they discovered lots more asteroids – so it no longer made sense to call them all planets, and the number fell down to 8 until Pluto was found in 1930.
After 1930, until other Kuiper belt objects were found, 9 did seem to be the magic number. But just as there were too many asteroids for any of them to be be “planets”, we now know about too many KBOs for all of them to be planets – and there’s no really clear dividinf line, so it does make sense to go back to 8. And it’s going to stay at 8, unless/until something much more massive than Pluto is discovered beyonf the Kuiper belt.
Define “too many to be planets”.
I have an idea: let’s put it up for a vote at a meeting of the International Astronomical Union.
Of course it’s a fuzzy line. When we only knew about Ceres, or when we only knew about Pluto, then they looked like planets. When we knew about 3 asteroids, or about 3 KBOs, then perhaps they all are planets. But when you have a dozen or so in the category, and they are being discovered with increasing frequency, then you go back and redraw the dividing line.
I took it to mean that Pluto hadn’t cleared Charon out of its orbit, since it isn’t a true satellite (in the sense that Pluto and Charon revolve around a common point in space).
So “double planets” are a no-go from the start.
So a system with a star the size of the Sun, and two objects the size of Jupiter and Saturn in the same orbit around the star, but orbiting each other around a centre of mass in between them, would not have a “planet” but would have two “dwarf planets”? That sounds very strange to me.
Eeew.
From CNN.com:
Well, I guess the New Horizons probe will just have to turn around and come on back home.
Yeah, I agree the new “8 planet” definition isn’t really any less problematic than the “12+ planet” definition was. I wish next week some enterprising astronomer would discover a true “double planet” orbiting some nearby star–two big, unambiguous planets, orbiting each other, in orbit around their star–just to mess with the IAU’s heads.
Sorry for the double post, but I’m not sure this sentence from CNN.com really makes any sense either:
I think it’s more that Ceres and Pluto orbit in amongst a whole bunch of other similar-sized bodies, that they’re part of “belts” (the Asteroid Belt and the Kuiper Belt) than that Pluto is sometimes inside but mostly outside the orbit of Neptune.
I’m guessing the only winners here are publishers of astronomy textbooks and posters.