Solar System Trivia

I tried Shumaker... (D'OH)

Do you work under the DoD by any chance?

I never heard of that one, either, but eventually got it guessing random shapes.

“Dwarf planets” actually don’t exist, technically — it’s a falsified classification that the IAU created because of recent discoveries in the Kuiper Belt. Basically they just threw a hissy fit and created three criteria (of which the third is clearly biased) for planetary status because they didn’t want a hundred planets. Apparently no one could think you just make tiers of planets by gravitational dominance or form or the like. Now, the third criterion: “An object must have cleared the neighbourhood around its orbit.” What does that mean? Well…technically nothing. It’s just an excuse, a cover-up. According to the Stern-Levinson parameter, Lamba = k(M^2/P), where k is a constant based on the measurement of the mass, M is the mass of the object, and P is the orbital period. If Lambda < 1, the object is not a planet. That’s basically what the third criteria means — that the object could have cleared all other objects from the orbit in the time of the Solar System. (See continued.)

(Continued…) Now, how is this biased? Well, let’s do the math (kind of). Since the orbital period is the denominator, if we maintain the same mass, every time we extend the orbital period, Lambda shrinks, and it does so pretty rapidly, and because of Kepler’s Second Law, the farther out you go, the slower the orbit. If 1 AU is 1 year, 2 AU isn’t 2 years; it’s actually closer to 3. Thus, P will rapidly inflate the further from the Sun you get, which means that at a certain distance, P with exceed M^2 and the fraction will fall below a value of 1. And the constant k will not always save it. So in theory, if we cleared all objects within x AU of its orbit, as long as Lambda is less than one, the IAU doesn’t care. Because the third parameter is just an odd way of saying the Stern-Levinson parameter, they would be saying that the object had not cleared an orbit that doesn’t have any objects to clear. So, yeah, the third parameter is clearly biased against the Kuiper Belt. (See continued.)

(Continued.) Also, technically speaking, the IAU may have just straight made up the criteria on the spit after deciding we only had eight planets, rather than creating the criterion first and testing the known objects. This certainly seems to explain the odd third criterion. They had to come up with a way to eliminate all small, distant bodies, so they came up with a criterion that basically says that unless an object is absolutely massive, if it orbits in the Kuiper Belt, it is not allowed to be a planet. Also, look at this, from Resolution B5, which is from where we get the classifications: “The IAU therefore resolves that planets…be defined…in the following way:

(1) A planet^1 [I must write it that way becausw I cannot type footnote markers in the comments] is a celestial body that…”. Notice the footnote? Now, at the bottom of the page, that footnote says: “The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.” (See continued.)

(Continued.) Thus it appears that the IAU has first deemed the eight planets, and then has built the parameters around their premade decision. This is decidedly unscientific — as is the third parameter in and of itself. After all, if we found an Earth-sized object, or likely larger, orbiting in a largely empty part of the system, it would likely fail the third criterion because Lambda would be less than 1, yet it would have such a minimal neighbourhood to clear in the first that the third criterion would be pointless to apply. Yet because of the three criteria, such an object would, indeed, be denied planetary status. If we moved Earth to the edge of the inner Oort Cloud, it would fail the third criterion and no longer be a planet, even though the objects in that region are very sparsely populated and Earth would have very little to clear in the first place. This is why most planetary scientists prefer a geophysical definition of “If it’s round, it’s a planet.”

At times I wish I could send Daniel crashing into Jupiter... #COYS

Too solar-centric.

Great Red Spot

I'm glad I wasn't the only one who thought that.

I say the Major system ends at the heliopause, the Minor system ends at the start of the Oort Cloud, and the full system, the full extent of the Sun’s gravitational influence, ends at the due of the Oort Cloud.