Eithalica (planets)

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Eithalica

Type

planet system

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]:

The celestial bodies of Eithalica include:

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

  1. That is, the distance from the center of Eith to the outermost surface of one of its moons.
  2. 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.