There may be a 9th planet (that’s not Pluto)

[Madner Kami]

I am pretty sure if we never made the difference between planets and dwarf planets, moons will still be called moons and large asteroids even if large like Ceres would be still called asteroids. And Pluto would still be a planet. Just like before.

That's the whole thing that sparked the dwarf-planet distinction: The discovery of objects that are planet-like but smaller than most moons. You could either upgrade moons to be "planets circling a planet" or downgrade these objects to "planets that haven't cleared out their own orbit from large debris"*. Eris, the currently largest known of these trans-neptunian objects is just a few kilometers smaller in diameter than Pluto (2,326 vs 2,376.6). Most of the other Kuiper-Belt objects are hovering around a 1,000km diameter, thus being 30% larger than the mainland USA's area and they're all doing the exact same thing as the main planets: They have a roughly spheroid shape (no planet is a perfect sphere, they're all wider around the equator than along their rotational axis, due to the centrifugal force of their rotation) and circle the sun on a relativley stable orbit. Asteroids fail particularly on the "roughly spheroid shape"-part of the definition.

Fun fact: Earth just barely escapes the dwarf planet distinction itself, due to a particularly large object circling the sun on the exact same orbit, which qualifies for a planet in it's own right: Luna. The reason being, that Earth and Luna circle around a common barycenter (centerpoint of the rotation of both objects around each other) that is about 25% of the Earth's radius beneath the Earth's surface. It's predicted, that Luna will have moved so far away from Earth, that the barycenter of the twin-system is outside Earth's radius in about 5 billion years. At that point we'll have to start arguing about whether Earth is a dwarf-planet or if we create a distinction for "orbiting the sun, are roughly spheroid in shape and have cleared their common orbit of large debris except for each other" aka twin- (or multiple-)-planets. But then again, we might be lucky, because the sun will have blown up to a red giant and likely have swallowed Earth by that point, so we might be spared of the horrible fate of living on a dwarf planet. Size matters, yo!

[McAvoy]

I am pretty sure if we never made the difference between planets and dwarf planets, moons will still be called moons and large asteroids even if large like Ceres would be still called asteroids. And Pluto would still be a planet. Just like before.

That's the whole thing that sparked the dwarf-planet distinction: The discovery of objects that are planet-like but smaller than most moons. You could either upgrade moons to be "planets circling a planet" or downgrade these objects to "planets that haven't cleared out their own orbit from large debris"*. Eris, the currently largest known of these trans-neptunian objects is just a few kilometers smaller in diameter than Pluto (2,326 vs 2,376.6). Most of the other Kuiper-Belt objects are hovering around a 1,000km diameter, thus being 30% larger than the mainland USA's area and they're all doing the exact same thing as the main planets: They have a roughly spheroid shape (no planet is a perfect sphere, they're all wider around the equator than along their rotational axis, due to the centrifugal force of their rotation) and circle the sun on a relativley stable orbit. Asteroids fail particularly on the "roughly spheroid shape"-part of the definition.

Fun fact: Earth just barely escapes the dwarf planet distinction itself, due to a particularly large object circling the sun on the exact same orbit, which qualifies for a planet in it's own right: Luna. The reason being, that Earth and Luna circle around a common barycenter (centerpoint of the rotation of both objects around each other) that is about 25% of the Earth's radius beneath the Earth's surface. It's predicted, that Luna will have moved so far away from Earth, that the barycenter of the twin-system is outside Earth's radius in about 5 billion years. At that point we'll have to start arguing about whether Earth is a dwarf-planet or if we create a distinction for "orbiting the sun, are roughly spheroid in shape and have cleared their common orbit of large debris except for each other" aka twin- (or multiple-)-planets. But then again, we might be lucky, because the sun will have blown up to a red giant and likely have swallowed Earth by that point, so we might be spared of the horrible fate of living on a dwarf planet. Size matters, yo!

Yes I have seen the various articles on the why. I get it.

There are moons larger than our moon. Earth is the only rocky planet (as in not gas giant) to have a moon. Also Earth outside the Sun is the densest object in the system. Venus comes to a very close third.

Chances are most if not all of the moons in system were captured which kinda shows how much Jupiter and Saturn cleaned up the system. Just thinking about how many loose free flying planetoids flying around waiting to fuck shit up. Aka like our proto Earth.

The amount of 'debris' in this system certainly would bring up how cluttered other solar systems could be. How many planets would there be, how many moons, or moon size objects just chilling there in the system.

[Riedquat]

Yes I have seen the various articles on the why. I get it.

There are moons larger than our moon. Earth is the only rocky planet (as in not gas giant) to have a moon. Also Earth outside the Sun is the densest object in the system. Venus comes to a very close third.

Chances are most if not all of the moons in system were captured which kinda shows how much Jupiter and Saturn cleaned up the system. Just thinking about how many loose free flying planetoids flying around waiting to fuck shit up. Aka like our proto Earth.

The amount of 'debris' in this system certainly would bring up how cluttered other solar systems could be. How many planets would there be, how many moons, or moon size objects just chilling there in the system.

Mars has moons, although they're captured asteroids. Most of the gas giant moons probably aren't captures but formed with the planets they orbit (unlike the Earth's moon, where evidence points towards it being the result of an early solar system collision). Triton is a very definite exception to this, and looks like a capture, as do various other very small moons (Triton being unique in not being small).

Of course the whole planet / dwarf planet thing is really trying to put categories on something that in truth is largely a continuum. This is even more apparent in some minor bodies that get both asteroid and comet designations.

In some ways it would make more sense to classify the gas planets as a fundamentally different type of object to the rocky things.

[Madner Kami]

Of course the whole planet / dwarf planet thing is really trying to put categories on something that in truth is largely a continuum. This is even more apparent in some minor bodies that get both asteroid and comet designations.

Very true. There's a point where the distinction between a large asteroid and a small dwarf planet is largely a question of "How far you have to zoom out to see the entire object and can you still notice the mountains at that range?" Heck, even the "cleared it's orbit of debris" is kinda silly, because Earth has "Trojans", asteroids which are on the same orbit as Earth, locked by gravitation into both LaGrange-points ahead and behind us on our orbit, so Earth clearly hasn't cleared all of it's orbit of debris and never will (unless something drastically upsets the current gravitational equilibrium of our solar system and if that happens, we got bigger problems than worrying about the distinction between asteroids, (dwarf) planets and gas giants ).

[McAvoy]

Yes I have seen the various articles on the why. I get it.

There are moons larger than our moon. Earth is the only rocky planet (as in not gas giant) to have a moon. Also Earth outside the Sun is the densest object in the system. Venus comes to a very close third.

Chances are most if not all of the moons in system were captured which kinda shows how much Jupiter and Saturn cleaned up the system. Just thinking about how many loose free flying planetoids flying around waiting to fuck shit up. Aka like our proto Earth.

The amount of 'debris' in this system certainly would bring up how cluttered other solar systems could be. How many planets would there be, how many moons, or moon size objects just chilling there in the system.

Mars has moons, although they're captured asteroids. Most of the gas giant moons probably aren't captures but formed with the planets they orbit (unlike the Earth's moon, where evidence points towards it being the result of an early solar system collision). Triton is a very definite exception to this, and looks like a capture, as do various other very small moons (Triton being unique in not being small).

Well depends on those moons' composition. If I recall scientists had issues with one of the original ideas that the Moon was formed while in orbit of Earth while Earth was being formed too.

Just having a hard time thinking a rocky moon forming over Jupiter or Saturn while they themselves were sucking up all of the gaseous elements in the system. Makes more sense to me that these moons would form or partially formed on their own before getting pulled in by Jupiter or Saturn's gravity.

The again who knows maybe a proto-Jupiter once had a giant ring system in its orbit before those rings condensed into moons or something.

[Madner Kami]

The again who knows maybe a proto-Jupiter once had a giant ring system in its orbit before those rings condensed into moons or something.

With very few exceptions: Ring systems are temporary. You can either consider the rings as "was an object not too long ago" or "is going to be an object soon (again)".

[McAvoy]

The again who knows maybe a proto-Jupiter once had a giant ring system in its orbit before those rings condensed into moons or something.

With very few exceptions: Ring systems are temporary. You can either consider the rings as "was an object not too long ago" or "is going to be an object soon (again)".

My point was that we actually dedicated super computer science to at least theoretically prove the Moon might have been a remnant of the proto planet that collided with the proto Earth to create the Moon. Thus, reinforcing the findings of the moon samples brought back from the Apollo missions.

Where as, we have no such samples and still have similar issues of how these moons were formed. Were they captured? Were they formed? We don't know.