Eithalica (planets): Difference between revisions
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|key3 = Total mass | |key3 = Total mass | ||
|val3 = 23.05 × 10<sup>24</sup> [[Wikipedia:Kilogram|kg]] | |val3 = 23.05 × 10<sup>24</sup> [[Wikipedia:Kilogram|kg]] | ||
|key4 = | |key4 = Component radius<ref>That is, the distance from the center of [[Eith]] to the outermost surface of one of its moons.</ref> | ||
|val4 = 24.97 × 10<sup>6</sup> [[Wikipedia:Meter|m]] | |val4 = 24.97 × 10<sup>6</sup> [[Wikipedia:Meter|m]] | ||
|key5 = Siderial day | |key5 = Siderial day | ||
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|key8 = Axial tilt | |key8 = Axial tilt | ||
|val8 = … | |val8 = … | ||
|key9 = Members | |||
|val9 = | |||
* [[Eith]] | |||
* [[Chessol]] | |||
* [[Siothum]] | |||
* [[Temalar]] | |||
}} | }} | ||
'''Eithalica''' (pronounced “eye-THAL-ik-ah;& | '''Eithalica''' (pronounced “eye-THAL-ik-ah” — [[Wikipedia:International Phonetic Alphabet|{{smallcaps|ipa}}]]: /aiθˈælɪkə/) is a [[#Celestial Classification|planetary system]] of four bodies, or a '''“quadruple planet.”''' It is home to two [[Anthropomorphic intelligence|intelligent]] species<ref>That is, two ''known so far.'' Having experienced the [[Lethean Age]] closely followed by {{#spoiler:[[Wikipedia:First contact (science fiction)|first contact]] from [[Giefbin]]}}, the people of [[Chetnum (civilization)|Chetnum]] remain disproportionately ignorant of [[Siothum]], [[Temalar]], and the non-[[chesward]] parts of [[Eith]] even into [[their Space Age]].</ref>: | ||
* [[Klevem]], a humanoid species, and | * [[Klevem]], a humanoid species, and | ||
* [[Yalengem]], a flying [[Wikipedia:Tetrachromat|tetrachromat]] with pronounced [[Wikipedia:Bioluminescence|bioluminescence]]. | * [[Yalengem]], a flying [[Wikipedia:Tetrachromat|tetrachromat]] with pronounced [[Wikipedia:Bioluminescence|bioluminescence]]. | ||
The [[Wikipedia:celestial bodies|celestial bodies]] of Eithalica include [[Eith]], | The [[Wikipedia:celestial bodies|celestial bodies]] of Eithalica include: | ||
* [[Chessol]] (the primary moon for the [[Chetnum (civilization)|Chetnum]] civilization) | * [[Eith]], the one in the center and the largest (by a slim margin). | ||
* [[Siothum]] | * Three outer bodies or “moons” ([[#Celestial Classification|see below]]): | ||
* [[Temalar]] | ** [[Chessol]] (the primary moon for the [[Chetnum (civilization)|Chetnum]] civilization) | ||
** [[Siothum]] | |||
** [[Temalar]] | |||
= Physical Characteristcs = | = Physical Characteristcs = | ||
All the bodies in Eithalica have nearly the same physical characteristics: mass, mean radius, mean density, general composition, climate, etc. They even have comparable types of global ecosystems and share flora and fauna. | All the bodies in Eithalica have nearly the same physical characteristics: mass, mean radius, mean density, general composition, climate, etc. They even have comparable types of global ecosystems and share some [[:Category:Environment|flora and fauna]]. | ||
On top of these similarities, their orbital configuration is striking in at least four ways: | On top of these similarities, their orbital configuration is striking in at least four ways: | ||
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* All bodies are [[Wikipedia:Tidal locking|tidally locked]] to each other. | * All bodies are [[Wikipedia:Tidal locking|tidally locked]] to each other. | ||
* The system is radially symmetrical ([[#Paranatural Symmetry|see below]]). | * The system is radially symmetrical ([[#Paranatural Symmetry|see below]]). | ||
Due to the fast orbits of the moons, their [[Wikipedia:Roche limit|Roche limits]] are even closer to Eith’s surface than the moons themselves. This means that, although they are so [[Wikipedia:prolate|prolate]] that it's obvious to the naked eye, each moon is still internally stable. In fact the lack of variability in prolateness means no added stress from [[Wikipedia:Tidal heating|tidal flexing]] (and therefore no extra [[Wikipedia:volcanism|volcanism]]). | |||
= Celestial Classification = | = Celestial Classification = | ||
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Eithalica is a unique system that resists conventional classification. | Eithalica is a unique system that resists conventional classification. | ||
A | A casual observer might see that Eith sits permanently in the center of all the “lunar” orbits, and suppose this means Eith is the host for those orbits. But this is a deceptive consequence of [[#Paranatural Symmetry|the system’s overall symmetry]]. In reality, the gravity from Eith plays a smaller role in defining each moon’s orbit than does the combined gravity from the other two moons. So the system is truly mutual like a [[Wikipedia:Star system#Higher multiplicities|quadruple star]], but of [[Wikipedia:planet|planets]]. Hence it receives the term '''“quadruple planet.”''' | ||
In this wiki and other real-life English works, the outer bodies of Eithalica are still called “moons” in a virtual sense, and for simplicity. However, a [[Wikipedia:moons|moon]] is defined as a naturally occurring [[Wikipedia:satellite (disambiguation)|satellite]], i.e. a body which [[Wikipedia:orbit|orbits]] another. To say that one body orbits the other, and not ''vice versa,'' is to presume a hierarchy between the two which in the case of Eithalica and each of its moons is very tenuous. | In this wiki and other real-life English works, the outer bodies of Eithalica are still called “moons” in a virtual sense, and for simplicity. However, a [[Wikipedia:moons|moon]] is defined as a naturally occurring [[Wikipedia:satellite (disambiguation)|satellite]], i.e. a body which [[Wikipedia:orbit|orbits]] another. To say that one body orbits the other, and not ''vice versa,'' is to presume a hierarchy between the two which in the case of Eithalica and each of its moons is very tenuous. |
Revision as of 04:34, 29 October 2022
Type |
|
---|---|
Number of bodies |
4 |
Total mass |
23.05 × 1024 kg |
Component radius[1] |
24.97 × 106 m |
Siderial day |
… |
Synodic day |
… |
Orbital period |
… |
Axial tilt |
… |
Members |
|
Eithalica (pronounced “eye-THAL-ik-ah” — ipa: /aiθˈælɪkə/) is a planetary system of four bodies, or a “quadruple planet.” It is home to two intelligent species[2]:
- Klevem, a humanoid species, and
- Yalengem, a flying tetrachromat with pronounced bioluminescence.
The celestial bodies of Eithalica include:
- Eith, the one in the center and the largest (by a slim margin).
- Three outer bodies or “moons” (see below):
Physical Characteristcs
All the bodies in Eithalica have nearly the same physical characteristics: mass, mean radius, mean density, general composition, climate, etc. They even have comparable types of global ecosystems and share some flora and fauna.
On top of these similarities, their orbital configuration is striking in at least four ways:
- All three “moons” orbit extremely close to Eith (and each other) with very short periods.
- All orbits are geostationary to Eith, a condition kept stable by tidal forces.
- All bodies are tidally locked to each other.
- The system is radially symmetrical (see below).
Due to the fast orbits of the moons, their Roche limits are even closer to Eith’s surface than the moons themselves. This means that, although they are so prolate that it's obvious to the naked eye, each moon is still internally stable. In fact the lack of variability in prolateness means no added stress from tidal flexing (and therefore no extra volcanism).
Celestial Classification
Eithalica is a unique system that resists conventional classification.
A casual observer might see that Eith sits permanently in the center of all the “lunar” orbits, and suppose this means Eith is the host for those orbits. But this is a deceptive consequence of the system’s overall symmetry. In reality, the gravity from Eith plays a smaller role in defining each moon’s orbit than does the combined gravity from the other two moons. So the system is truly mutual like a quadruple star, but of planets. Hence it receives the term “quadruple planet.”
In this wiki and other real-life English works, the outer bodies of Eithalica are still called “moons” in a virtual sense, and for simplicity. However, a moon is defined as a naturally occurring satellite, i.e. a body which orbits another. To say that one body orbits the other, and not vice versa, is to presume a hierarchy between the two which in the case of Eithalica and each of its moons is very tenuous.
Theoretically all bodies in a system exert at least some gravitational force on all other bodies in the system, but for most planet systems the masses involved are defined by a hierarchy so enormous that it’s unmistakable and indisputable. Often the influence of the smaller bodies on the larger is negligible.
In real-life astronomy so far, most disputes on this topic concern possible dwarf planets. Every one of Eithalica’s bodies is too large to be remotely considered “dwarf-size,” yet it still exists at an utmost edge of these definitions—a new, somewhat different edge.
Paranatural Symmetry
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Footnotes
- ↑ That is, the distance from the center of Eith to the outermost surface of one of its moons.
- ↑ That is, two known so far. Having experienced the Lethean Age closely followed by , the people of Chetnum remain disproportionately ignorant of Siothum, Temalar, and the non-chesward parts of Eith even into their Space Age.