SSTO Crasher Posted January 20, 2022 Share Posted January 20, 2022 There is something I am concerned about, I was reading about why Pulte was demoted, and it’s because it was not the dominant object in its orbit. But rask and rusk are orbiting each other, meaning neither of them is the dominant objects in their orbit, so are they really planets. Link to comment Share on other sites More sharing options...
Maria Sirona Posted January 20, 2022 Share Posted January 20, 2022 Pulte? There is no such thing as Pulte. Link to comment Share on other sites More sharing options...
AtomicTech Posted January 20, 2022 Share Posted January 20, 2022 Rask and Rusk are planets, they're a binary system. The Devs have mentioned this before. Link to comment Share on other sites More sharing options...
SSTO Crasher Posted January 20, 2022 Author Share Posted January 20, 2022 On 1/20/2022 at 2:23 PM, Maria Sirona said: Pulte? There is no such thing as Pulte. Expand I meant Pluto Link to comment Share on other sites More sharing options...
Maria Sirona Posted January 20, 2022 Share Posted January 20, 2022 On 1/20/2022 at 2:25 PM, SSTO Crasher said: meant Pluto Expand Oh now i understand. Anyway to my point! The third criteria of the IAU planet definition is dumb because Jupiter would then technically not be a planet because of the trojans. Discarding it, i see no reason to not consider the two of Rask ans Rusk planets. Link to comment Share on other sites More sharing options...
SSTO Crasher Posted January 20, 2022 Author Share Posted January 20, 2022 Well Jupiter is clearly the dominant object in its orbit Link to comment Share on other sites More sharing options...
Omni122 Posted January 20, 2022 Share Posted January 20, 2022 On 1/20/2022 at 2:31 PM, Maria Sirona said: Oh now i understand. Anyway to my point! The third criteria of the IAU planet definition is dumb because Jupiter would then technically not be a planet because of the trojans. Discarding it, i see no reason to not consider the two of Rask ans Rusk planets. Expand Actually, Jupiter would still be a planet. Jupiter is the most massive object in it’s orbit by a long shot. Pluto isn’t the most massive object in it’s orbit. Clearing its orbit means that an object makes up the vast majority of the mass inside its orbit. Link to comment Share on other sites More sharing options...
shdwlrd Posted January 20, 2022 Share Posted January 20, 2022 Rask and Rusk are planets because the developers say they are planets. The actual definition and criteria for planets don't matter. Link to comment Share on other sites More sharing options...
Deadmeat24 Posted January 20, 2022 Share Posted January 20, 2022 They orbit each other, but also orbit their sun as a pair. So in that sense they would be the dominant objects in their orbit. Link to comment Share on other sites More sharing options...
intelliCom Posted January 20, 2022 Share Posted January 20, 2022 There's a new definition for planet being proposed, which would essentially consider moons to also be planets of their own, ignoring the "clearing of the neighbourhood". Also, as an important note: If a planet could only be a planet if it's cleared its neighbourhood, would this make Saturn a dwarf planet? Link to comment Share on other sites More sharing options...
K^2 Posted January 21, 2022 Share Posted January 21, 2022 I'm absolutely in favor of classifying the Moon as a planet. While Earth is massive enough of the two that the Earth-Moon barycenter is entirely within Earth's surface, Earth's gravity is still weaker than the Sun's as far as effects on the Moon. That is, Moon primarily orbits the Sun, not the Earth, and merely co-orbits the Earth. Another way to look at it is that Moon's trajectory around the Sun is everywhere convex - it is always accelerating towards the Sun. This isn't true for any other moon in the Solar System. All of the other moons are pulled by their primary with enough force that sometimes they are pulled away from the Sun. That really shows that the moons are bound to their planet. Since this is not the case for the Moon, it really doesn't make sense to say that it orbits the Earth as its primary. I would also argue that barycenter situation is temporary, as the Moon is receding, and this will eventually resolve itself. Yes, it's billions of years in the future, but I think it's a good enough example to use the tug-of-war definition instead of the barycenter one. There might be some naming confusion. But if it gets too confusing, we can start referring to the Moon as Luna, clearly distinguishing it from various moons of the solar System. But that's optional. Proper classification is the important bit here. Link to comment Share on other sites More sharing options...
Maria Sirona Posted January 21, 2022 Share Posted January 21, 2022 On 1/20/2022 at 6:14 PM, Omni122 said: Actually, Jupiter would still be a planet. Jupiter is the most massive object in it’s orbit by a long shot. Pluto isn’t the most massive object in it’s orbit. Clearing its orbit means that an object makes up the vast majority of the mass inside its orbit. Expand And what do you define as "Pluto's orbit"? Link to comment Share on other sites More sharing options...
Meb Kat Posted January 21, 2022 Share Posted January 21, 2022 On 1/20/2022 at 9:31 PM, intelliCom said: There's a new definition for planet being proposed, which would essentially consider moons to also be planets of their own, ignoring the "clearing of the neighbourhood". Also, as an important note: If a planet could only be a planet if it's cleared its neighbourhood, would this make Saturn a dwarf planet? Expand I think Saturn would still be considered a planet as the rings orbit Saturn itself, and not around the sun the way the Trojans of Jupiter do. Link to comment Share on other sites More sharing options...
KerikBalm Posted January 21, 2022 Share Posted January 21, 2022 There is a specific parameter that can be computed, the Stern-Levinson parameter. https://en.m.wikipedia.org/wiki/Clearing_the_neighbourhood Its actually a measure of how much it gravitationally dominates the orbit/"clearing" power. Trojans at L4 and L5 don't matter (Jupiter). Having another body in an orbital resonance doesn't matter (Neptune, Pluto is in an orbital resonance with it). Link to comment Share on other sites More sharing options...
Pthigrivi Posted January 22, 2022 Share Posted January 22, 2022 For the record I support “Pulte” as a KSP2 planet name, if the gods are listening. Link to comment Share on other sites More sharing options...
jimmymcgoochie Posted January 22, 2022 Share Posted January 22, 2022 On 1/21/2022 at 2:35 AM, K^2 said: Another way to look at it is that Moon's trajectory around the Sun is everywhere convex - it is always accelerating towards the Sun. Expand Eh? Surely the Moon must move away from the Sun for half its orbit around the Earth? Anything constantly accelerating towards the Sun would eventually crash into it. Link to comment Share on other sites More sharing options...
KerikBalm Posted January 22, 2022 Share Posted January 22, 2022 On 1/22/2022 at 6:21 AM, Pthigrivi said: For the record I support “Pulte” as a KSP2 planet name, if the gods are listening. Expand Oh yes, I support this. On 1/22/2022 at 9:33 AM, jimmymcgoochie said: Eh? Surely the Moon must move away from the Sun for half its orbit around the Earth? Anything constantly accelerating towards the Sun would eventually crash into it. Expand He said accelerating toward, not moving toward. An object in orbit is always accelerating toward the body it orbits. It's better to discuss convexity/concavity. All other moons have concavities in their orbit with respect to the sun, our moon doesn't. However, if you put earth-moon where Pluto is, you would observe a concavity, so I am not sure this is so relevant Link to comment Share on other sites More sharing options...
Bej Kerman Posted January 22, 2022 Share Posted January 22, 2022 On 1/20/2022 at 6:28 PM, shdwlrd said: Rask and Rusk are planets because the developers say they are planets. The actual definition and criteria for planets don't matter. Expand You're a planet because I say you're a planet. On 1/20/2022 at 2:23 PM, SSTO Crasher said: There is something I am concerned about, I was reading about why Pulte was demoted, and it’s because it was not the dominant object in its orbit. But rask and rusk are orbiting each other, meaning neither of them is the dominant objects in their orbit, so are they really planets. Expand Rask and Rusk are the dominant bodies in their orbit. Link to comment Share on other sites More sharing options...
Ashandalar Posted January 22, 2022 Share Posted January 22, 2022 On 1/22/2022 at 9:33 AM, jimmymcgoochie said: Eh? Surely the Moon must move away from the Sun for half its orbit around the Earth? Anything constantly accelerating towards the Sun would eventually crash into it. Expand Always accelerating towards the sun is different from always moving towards the sun. In any Keplerian orbit, like every one in the game, you are always accelerating towards the centre of mass of the body you are orbiting. Link to comment Share on other sites More sharing options...
Pthigrivi Posted January 22, 2022 Share Posted January 22, 2022 (edited) On 1/20/2022 at 2:23 PM, SSTO Crasher said: Pulte Expand Funny question about this, I know we all sign terms of service on this board and Im sure we’d all be over the moon for ideas like this to actually get incorporated in the game but do you think out of an abundance of caution intercept would deliberately not use the name ‘Pulte’ cause it didn’t come from their shop? Edited January 22, 2022 by Pthigrivi Link to comment Share on other sites More sharing options...
K^2 Posted January 22, 2022 Share Posted January 22, 2022 On 1/22/2022 at 9:33 AM, jimmymcgoochie said: Eh? Surely the Moon must move away from the Sun for half its orbit around the Earth? Anything constantly accelerating towards the Sun would eventually crash into it. Expand I think this might be easier with an illustration. Plotting Moon's actual orbit around the Sun is kind pointless, because it pretty much looks like a circle. But imagine a fictional system where the moon is making only 4 revolutions in a year at a significant distance from its companion. Then the path around the primary star might look something like this. Note that the moon, as pictured, is always accelerating (curving) towards the center. But the distance does, in fact, vary. It does move closer to the center sometimes, and further away at other times. This is because to just stay at a constant distance, you have to be going around a circle. And as you're going around a circle, you are accelerating (curving) towards the center at a constant rate. If you accelerate towards the center even faster, you will start moving closer. If you accelerate less, but still towards the center, you'll start moving away. The Moon is in a similar situation. Earth's gravity does nudge it a little closer or further from the Sun, but the Sun's gravity is always the dominant force. So the Moon travels around the Sun in a near-circular path, with just a little bit of a curvature modulation caused by Earth. Link to comment Share on other sites More sharing options...
SSTO Crasher Posted January 23, 2022 Author Share Posted January 23, 2022 Yes but any moons orbit around earth at that distance would make the moon leave orbit, making your point pointless as the earth would clearly dominate the orbit of the 2 On 1/22/2022 at 10:54 PM, K^2 said: I think this might be easier with an illustration. Plotting Moon's actual orbit around the Sun is kind pointless, because it pretty much looks like a circle. But imagine a fictional system where the moon is making only 4 revolutions in a year at a significant distance from its companion. Then the path around the primary star might look something like this. Note that the moon, as pictured, is always accelerating (curving) towards the center. But the distance does, in fact, vary. It does move closer to the center sometimes, and further away at other times. This is because to just stay at a constant distance, you have to be going around a circle. And as you're going around a circle, you are accelerating (curving) towards the center at a constant rate. If you accelerate towards the center even faster, you will start moving closer. If you accelerate less, but still towards the center, you'll start moving away. The Moon is in a similar situation. Earth's gravity does nudge it a little closer or further from the Sun, but the Sun's gravity is always the dominant force. So the Moon travels around the Sun in a near-circular path, with just a little bit of a curvature modulation caused by Earth. Expand Link to comment Share on other sites More sharing options...
K^2 Posted January 23, 2022 Share Posted January 23, 2022 On 1/23/2022 at 1:13 AM, SSTO Crasher said: Yes but any moons orbit around earth at that distance would make the moon leave orbit, making your point pointless as the earth would clearly dominate the orbit of the 2 Expand Our Moon is in that situation and clearly hasn't left Earth's vicinity yet. Sun's gravity on the Moon is stronger than Earth's. Sun is the dominant body, and the Moon's trajectory is always curved towards the Sun. If you think that this somehow contradicts Earth and Moon continuing to travel around the Sun together, evidently, you are missing something. Link to comment Share on other sites More sharing options...
Maria Sirona Posted January 23, 2022 Share Posted January 23, 2022 On 1/23/2022 at 12:21 PM, K^2 said: If you think that this somehow contradicts Earth and Moon continuing to travel around the Sun together, evidently, you are missing something. Expand Well then i am too. If Sun's gravity is stronger on the Moon than Earth's then how does that not contradict the Moon orbiting the Earth Link to comment Share on other sites More sharing options...
SSTO Crasher Posted January 23, 2022 Author Share Posted January 23, 2022 Following this logic there would be no planets because the gravity of the sun is the dominant gravitational power in the entire system, we are talking about the dominant object in earths orbital height, and the earth clearly has the dominant power over the moon as the moon is orbiting the earth but we have swayed off topic Link to comment Share on other sites More sharing options...
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