More planets in our solar system

[Mitchz95]

I don't really think "planet" should be have a formal definition at all. Just make it a generic term interchangeable with "world" and let people call them what they want. And a moon is just a world that orbits another world.

[sevenperforce]

Here's my proposed hierarchy, with terms only:

Star

Brown dwarf star

Main sequence star

Degenerate star

World

Planet

Major planet

Minor planet

Moon

Fragmentary body

Natural satellite

Comet

Short period comet

Long period comet

Asteroid

Centaur

Meteoroid

Then you have modifiers, like trojan, binary, and so forth. Some moons could even be classified as "planetary moons" if they are large enough to be major planets if not orbiting a larger primary.

Edited March 29, 2017 by sevenperforce

[IllyrianTheGreat]

12 hours ago, sevenperforce said:

Here's my proposed hierarchy, with terms only:

Star

Brown dwarf star

Main sequence star

Degenerate star

World

Planet

Major planet

Minor planet

Moon

Fragmentary body

Natural satellite

Comet

Short period comet

Long period comet

Asteroid

Centaur

Meteoroid

Then you have modifiers, like trojan, binary, and so forth. Some moons could even be classified as "planetary moons" if they are large enough to be major planets if not orbiting a larger primary.

That is a lot of categories...

Simpler would be making only few of them like:
- asteroid
- planet
- star

There is no need to make special category for moons, since every moon could be either asteroid or planet.

[Steel]

40 minutes ago, IllyrianTheGreat said:

That is a lot of categories...

Simpler would be making only few of them like:
- asteroid
- planet
- star

There is no need to make special category for moons, since every moon could be either asteroid or planet.

But that misses the point of what a lot of people have been saying, there is (at least to lot of people) a fairly major difference between a planet and a moon that should be recognised it their names.

 

I think the main issue here boils down to the fact that this naming system is mostly used by two groups who have wildly different needs from a naming system:

1. Planetary Scientists, whose argument goes something like "When you're studying the body itself, there's no fundamental difference between a moon and a planet, so why not call them both planets?"

2. Astronomers/Astrophysicists, whose argument goes something like "Of course they're fundamentally different! Just look at their orbits, one directly orbits the star, the other does not"

The issue arises because these two view are fundamentally incompatible. We've had to decide whether to name them based mostly on the characteristics of the body or mostly on the characteristics of it's orbit, but the side that we've come down on won't make everyone happy. (of course current definitions do specify that the body must be gravitationally rounded, but is mostly based on orbital behavior)

Edited March 30, 2017 by Steel

[IllyrianTheGreat]

4 minutes ago, Steel said:

But that misses the point of what a lot of people have been saying, there is (at least to lot of people) a fairly major difference between a planet and a moon that should be recognised it their names.

 

I doing other way... if complicated category set can't cover unambiguously 100% of cases then it is useless. It is better to use less categories and think about individual properties of each body.

[kerbiloid]

All big round things - "planet".

"Senior planet", "Royal planet" or "Peer planet" - those who orbit round the star, (As "suzerain planet" would be often misspelled).

"Vassal planet" - those who orbit round "senior/royal planet".

More particular cases:

"Prince planet": Jupiter, Saturn. Hydrogen wannabe-stars.

"Duke planet": Uranus, Neptune. Bigger than a count, but much smaller than a prince.

"Count planet": Earth, Venus, Mars. 
Also, this makes Earth and Mars colonies "country" in the most wide sense of the word.

"Baron planet": Mercury, Ganimede, Moon. Too small to be a count, but much bigger than others.

"Baronet planet": Pluto, Ceres. They can hope.

"Squire    planet": Mimas, Charon (could be a baronet, though belongs to Pluto).

"Plebs": asteroids, comets, lesser planet satellites. Can be ranked too, but why?

Though, Earth and Moon should be highlighted.
First, they are "she" because Mother Nature and so on. So, "-ess".
Then, as Earth (as planet) is a frontier feud with extended rights and privileges, it's "advanced countess".
And as Moon is very important, too, thus it's "advanced baroness".

So, two special planets:
"Marquess planet": Earth (subclass of "count planets").
"Viscountess planet": Moon (subclass of "baron planets").

Edited March 30, 2017 by kerbiloid

[Hypercosmic]

According to the new, purposed definition: "the word 'planet' has a lot of impact on people. Some even ask 'Why are you sending probes to Pluto? It's not a planet.' and right now he got angry. This proposal considers the physical properties of the object and not the interaction between that object and the others. It's more about planetary scientists' favor, led by the New Horizons team's leader Alan Stern.

- The new definition -

Stars - Any object that has once capable of fusing elements (Giant stars, main sequence stars, white dwarfs, brown dwarfs, etc.)

Planets - Any object that has never undergone nuclear fusion, but has sufficient self-gravitation to assume spheroid shape. (Planets, satellite planets)

Planetoids - Any object that has never undergone nuclear fusion, and has insufficient self-gravitation to assume spheroid shape. (Asteroids, comets, meteoroids, etc.)

[IllyrianTheGreat]

4 minutes ago, Hypercosmic said:

According to the new, purposed definition: "the word 'planet' has a lot of impact on people. Some even ask 'Why are you sending probes to Pluto? It's not a planet.' and right now he got angry. This proposal considers the physical properties of the object and not the interaction between that object and the others. It's more about planetary scientists' favor, led by the New Horizons team's leader Alan Stern.

- The new definition -

Stars - Any object that has once capable of fusing elements (Giant stars, main sequence stars, white dwarfs, brown dwarfs, etc.)

Planets - Any object that has never undergone nuclear fusion, but has sufficient self-gravitation to assume spheroid shape. (Planets, satellite planets)

Planetoids - Any object that has never undergone nuclear fusion, and has insufficient self-gravitation to assume spheroid shape. (Asteroids, comets, meteoroids, etc.)

So something like my idea... I would only put gas giants in stars category and add condition to planets... they have solid or liquid surface.

[Hypercosmic]

Just now, IllyrianTheGreat said:

So something like my idea... I would only put gas giants in stars category and add condition to planets... they have solid or liquid surface.

That won't work for anybody. Gas planets are much closer to terrestrial and ice giants than stars, so much that it has to separate 'heliophysics' from 'planetary science'. Also, ice giants and hot ocean planets both have gaseous 'surface'.

Try learn more about planetary science.

[IllyrianTheGreat]

2 minutes ago, Hypercosmic said:

That won't work for anybody. Gas planets are much closer to terrestrial and ice giants than stars, so much that it has to separate 'heliophysics' from 'planetary science'. Also, ice giants and hot ocean planets both have gaseous 'surface'.

Try learn more about planetary science.

Ok... so we would have planet Luna in solar system?

 

[Hypercosmic]

Just now, IllyrianTheGreat said:

Ok... so we would have planet Luna in solar system?

 

Satellite planet Luna.

[kerbiloid]

1 hour ago, Hypercosmic said:

Stars - Any object that has once capable of fusing elements (Giant stars, main sequence stars, white dwarfs, brown dwarfs, etc.)

Spoiler

1 hour ago, IllyrianTheGreat said:

Ok... so we would have planet Luna in solar system?

Luna is a star. It's capable of Helium-3 fusing element.

Edited March 30, 2017 by kerbiloid

[Hypercosmic]

Just now, kerbiloid said:

  Reveal hidden contents

Luna is a star. It's capable of Helium-3 fusing element.

No, Luna collected He-3 from Sol's solar wind.

[kerbiloid]

1 minute ago, Hypercosmic said:

No, Luna collected He-3 from Sol's solar wind.

Sun collected Hydrogen from Bing Bang.
(Third hand, of course.)

Edited March 30, 2017 by kerbiloid

[Hypercosmic]

5 minutes ago, kerbiloid said:

Sun collected Hydrogen from Bing Bang.
(Third hand, of course.)

Sol can fuse hydrogen into helium, thus it is a star.

Luna cannot fuse helium-3, thus it isn't a star.

[sevenperforce]

4 hours ago, IllyrianTheGreat said:

That is a lot of categories...

Simpler would be making only few of them like:
- asteroid
- planet
- star

There is no need to make special category for moons, since every moon could be either asteroid or planet.

There are only three top-level categories: star, world, and fragmentary body. These are based on the object's physical attributes, that is, planetary science. The subclassifications within each top-level category are based on the object's orbit, that is, astronomy.

As @Steel points out, there is a conflict between planetary scientists, who want to classify objects based on their physical attributes, and astronomers/astrophysicists, who want to classify objects based on their positions within the stellar system. I've pointed out that there is a third grouping as well: the lay public, which will continue to use terms based on the general idea of a hierarchy without giving thought to formal definitions. Using planetary science as the basis for the top level classification and astronomy as the basis for the subclassifications should, in principle, allow both types of scientists to have a meaningful classification system, while simultaneously aligning with the hierarchy-based nomenclature in common parlance.

[Hypercosmic]

2 minutes ago, sevenperforce said:

There are only three top-level categories: star, world, and fragmentary body. These are based on the object's physical attributes, that is, planetary science. The subclassifications within each top-level category are based on the object's orbit, that is, astronomy.

As @Steel points out, there is a conflict between planetary scientists, who want to classify objects based on their physical attributes, and astronomers/astrophysicists, who want to classify objects based on their positions within the stellar system. I've pointed out that there is a third grouping as well: the lay public, which will continue to use terms based on the general idea of a hierarchy without giving thought to formal definitions. Using planetary science as the basis for the top level classification and astronomy as the basis for the subclassifications should, in principle, allow both types of scientists to have a meaningful classification system, while simultaneously aligning with the hierarchy-based nomenclature in common parlance.

Can I rename those three celestial body categories to my own version? That 'world' sounds weird. In my meaning, 'world' means the human world.

And it's perfectly fine to have astronomer call Luna 'moon' and Pluto 'dwarf planet', and planetary scientists call them 'satellite planet' and 'planet' respectively. Just like how astronomer call all elements other than H₂ and He 'metal'.

[sevenperforce]

6 minutes ago, Hypercosmic said:

Can I rename those three celestial body categories to my own version? That 'world' sounds weird. In my meaning, 'world' means the human world.

And it's perfectly fine to have astronomer call Luna 'moon' and Pluto 'dwarf planet', and planetary scientists call them 'satellite planet' and 'planet' respectively. Just like how astronomer call all elements other than H₂ and He 'metal'.

The reason I like the term "world" rather than "planet" in the top-level classification is that it allows us to neatly skirt the astronomer problem. "Planet" has a distinct definition for astronomers, so using "world" allows planetary scientists and the general public to discriminate between spherical and nonspherical bodies readily. Then the astronomers can worry about whether a given world is a planet (orbital secondary to a star) or a moon (orbital secondary to another world).

I understand that the singular "world" is often assumed to refer to Earth, but the plural, "worlds", is readily understood as referring to other planet-like bodies. It's a very well-established usage; even the 1611 KJV uses it: "God hath in these last days spoken unto us by his Son, by whom also he made the worlds."

I don't particularly like "fragmentary body" but I'm not sure what would be better. "Planetisimal" is a possibility but that's not an easy term for the lay public to handle. "Planetoid" also sounds weird, and that would be a stretch if you are talking about a 3-foot-wide space rock.

[Hypercosmic]

1 minute ago, sevenperforce said:

The reason I like the term "world" rather than "planet" in the top-level classification is that it allows us to neatly skirt the astronomer problem. "Planet" has a distinct definition for astronomers, so using "world" allows planetary scientists and the general public to discriminate between spherical and nonspherical bodies readily. Then the astronomers can worry about whether a given world is a planet (orbital secondary to a star) or a moon (orbital secondary to another world).

I understand that the singular "world" is often assumed to refer to Earth, but the plural, "worlds", is readily understood as referring to other planet-like bodies. It's a very well-established usage; even the 1611 KJV uses it: "God hath in these last days spoken unto us by his Son, by whom also he made the worlds."

I don't particularly like "fragmentary body" but I'm not sure what would be better. "Planetisimal" is a possibility but that's not an easy term for the lay public to handle. "Planetoid" also sounds weird, and that would be a stretch if you are talking about a 3-foot-wide space rock.

MY DICT:

World: the human world (countries and politics stuffs, on one planet. For now, I'll put a globe with countries to represent that.)

Worlds: the human worlds (still countries and politics, but this time is on multiple celestial bodies. For example, if Phobos has its own sovereignty, I call it a 'world'.)

Since they were not fixed, however, I guess I'll keep these meanings ^ ^'

[sevenperforce]

Based on the principle "if you can't explain it, you don't understand it", I present the following lay explanation:

"It's a bit simpler now. There are three kinds of bodies in space: stars, which produce their own energy through fusion, worlds, which can't produce energy through fusion but are large enough that gravity makes them spherical, and fragmented bodies, which aren't large enough to be round. Worlds that directly orbit a star are planets; worlds that orbit other worlds are moons. Astronomers usually distinguish between major planets, which are large enough to have moons of their own, and minor planets, which may be orbited by fragmentary bodies but are too small to have moons of their own. Fragmentary bodies can be natural satellites, orbiting another body, asteroids, orbiting their star in a roughly circular orbit, or transients, which orbit their star in a very elliptical orbit."