Solar System

A map of the Sol System

The sun, the centerpiece of the system

The **Solar System** is a collection of 14 planets, 33 major moons, and numerous minor planets confined into 3 main belts which are gravitationally bound to to the star Sol. The Solar System is the only known inhabited star system, and is the home of Humans and the Loriset. Both races have divided the system between various independent political states, including the United Nations of Humanity (UNH), the Loriset Intendancy, and the Savisian Alliance.

## Architecture

The Solar System is commonly divided into three sections: The Inner System with four planets, Hestia, Vulcan, Mercury, and Venus, the Mid System with another four planets, Earth, Theia, Mars, and Phaeton, and the Outer System with four planets, Savis, Crius, Caelus, and Boreas. Beyond the outer system lies two clouds of ice and dust known as the Hills Cloud and the Oort Cloud, which contain the captured interstellar wanderer of Persephone and the brown dwarf Erebus, alongside uncountable numbers of dwarf planets.

## Differences from the Prime Timeline

The Project Alternis timeline forks from our own (referred to as the Prime Timeline on this wiki) at the very beginning of the formation of the solar system. Presumably some particles were arranged in a different way and it butterfly-effected from there, but the formation process went completely differently, causing the presence of a thick belt of asteroids known as the Handmaiden Belt beneath mercury alongside two extra planets. Theia never impacted earth, instead being captured into orbit, averting the creation of Luna. Planet V, here known as Demeter, never hit mars, instead existing as a dwarf planet in a 5:6 resonance with it. Jupiter and Saturn's nascent forms merged, forming Savis, with both of their moons coalescing around the singular planet. The fifth giant Crius was therefore never ejected and the asteroid belt was never forcibly cleared of most of its material, allowing the formation of Phaeton. Finally, Crius' presence forced the ice giant Caelus (Uranus) into an eccentric resonant orbit with it and each other, destabilizing the inner kuiper belt. At the moment, the brown dwarf Erebus is in the process of passing close to Sol, unlike in the Prime timeline.

## Inner System

### Hestia

By far the largest planet in the system, Hestia is a hot neptunian world orbiting dangerously close to the sun. With no resources to be extracted from its gaseous surface and an exceedingly hazardous radiation environment, Hestia is mostly ignored in politics. Hestia's sphere of influence is so small that a ship can barely leave the atmosphere before becoming untethered from its gravity, and so it has no moons, although it routinely captures large clouds of quasisatellites from the Handmaiden Belt.

### Handmaiden Belt

The Handmaiden Belt is a very thick, dusty, and exceedingly dangerous belt of asteroids and other smaller objects ranging from a dust grain to over 100 kilometers across. The main Handmaiden Belt is bounded on either side by Hestia and Vulcan, and contains the dwarf planet Praxis, although there are objects orbiting beneath the orbit of Hestia considered as part of the Belt and several large asterodis have been sighted with aphelia as far out as Mercury. The larger asteroids are often the sites of outposts run by one of the many nations in the system.

#### Praxis

The largest object within the Handmaiden Belt, Praxis is a hotly contested small dwarf planet ~1600 kilometers in radius. Praxis is currently controlled by the Loriset Intendancy after a series of climactic battles in the region failed to retake it from them.

### Vulcan

Vulcan is a large planet similar in size to Mars, and serves as the outer bounding of the Handmaiden Belt, to which it gives its name. Vulcan's surface is covered in lava rifts and igneous rock, and is loaded with useful resources. The planet is presently controlled by the United Nations of Humanity, and has no permanent moons within its orbit.

### Mercury

The smallest planet in the solar system, Mercury is a tiny ball of primarily iron orbiting beyond the Handmaiden Belt between Vulcan and Venus. Impacted by a large planetoid in its early history, Mercury had much of its mantle blasted away, leaving it the densest world in the solar system. Mercury has a single asteroidal moon, Selnas, and disputes over the planet's rich resource deposits was one of the key catalysts of the Homeworld Wars.

### Venus

Venus is a large terrestrial planet, the second largest in the system after Earth (Boreas is not considered terrestrial). Its thick atmosphere yet partly clear sky is unique in the solar system, and its expansive ring system magnifies its brightness to the point that it is dimly visible in the daytime sky. Venus and its moon Neith are both controlled by the United Nations of Humanity, with most of its population residing in the upper atmosphere of the planet.

## Mid System

### Earth / Theia

Often referred to as "twin planets", Earth and Theia are two superhabitable worlds with great surface biodiversity and are the only two known planets to support intelligent life. Earth and Theia exist in a binary configuration, with the larger of the pair, Earth, hosting three small moons, Lilith, Nestria, and Waltemath. Theia hosts the two tiny moons of Pickering and Petit. Earth is the largest terrestrial planet in the solar system and is home to Humans, and Theia is approximately half its size and home to the Loriset.

### Mars

The outermost planet before the Asteroid Belt, Mars is a small world. Its formation stifled by the wanderings of Hestia and Savis as well as the neighboring formation of Phaeton, Mars is barely a tenth the size of Earth and lacks a magnetic field. Mars was one of the earliest human colonies and remains under the control of the UNH, but its largest moon of Simud lies under the dominion of the Loriset Intendancy.

### Asteroid Belt

The first-discovered of the system's major collections of small bodies, the simply named Asteroid Belt is bounded by Mars and Savis on either side and split into two major zones by the gravitational influence of Phaeton. Its two largest objects, Ceres and Demeter are both independent states populated by both Humans and Loriset, who maintain frosty relationships with both sides of the Homeworld Wars.

#### Ceres

The largest resident of the outer belt, Ceres is partially made of icy materials with a thin crust of regolith. Ceres possesses large salt deposits, and is the center of a small nation encompassing several asteroids in the region.

#### Demeter

Demeter is the largest resident of the Asteroid belt as a whole, and is almost on the edge of being considered a planet. Demeter is also the center of an independent nation encompassing several asteroids, and maintains good relations with the UNH colony at Mars. It has no stable moons, and its orbit crosses mars in a 5:6 resonance.

### Phaeton

The outermost of the terrestrial planets, Phaeton seems fairly unremarkable at first glance, but its pockmarked icy surface hides countless subglacial lakes beneath the surface, each with a completely separate ecosystem of bacteria. After spending most of the war under the control of the Loriset Intendancy, the United Nations of Humanity recently took over the planet and its moons.

## Outer System

### Savis

The largest planet of the system, Savis' enormous bulk encompasses over half the mass in the solar system outside of Sol itself. It possesses a wide, gleaming ring system and a collection of 354 moons including nine spherical ones. Much of its lunar system is under the dominion of the Savisian Alliance, a state formed from the breakaway of several human and Loriset colonies with its capital at Ganymede. Its moon Europa is known to have a complex subglacial ecosystem.

### Titan

Titan is the only known *trojan planet*, existing in Savis' leading lagrange point. The planet is presently under quarantine enforced by the Savisian Alliance, with multiple observation posts on its surface remotely controlled from its moon Hyperion. Titan possesses a complex microscale ecosystem displaying full-scale food chains, although nothing on the planet grows larger than a sand grain.

### Crius

Crius is the second largest planet orbiting the Sun. Too remote to be an integral part of either superpower, Crius is mostly controlled by a selection of independent states arising from colonies planted centuries ago. To combat the pirates common to this distant region, the colonies at Eurybia, Perses, Astraios, and the minor moons have unified into a loose military alliance. The moon Eurybia has a complex ecosystem including very large life-forms.

### Caelus

The outermost gas giant in the main system, Caelus is also referred to as an ice giant. Its 31 moons range in size from pebbles to the enormous captured dwarf planet of Triton, site of the system's capital. The planet lacks clearly visible rings, and its extreme remoteness makes it impossible for either of the superpowers to project any sort of power to the planet. As such, the Miranda Treaty Organization was founded to bring order to the system.

### Kuiper Belt

The Kuiper Belt is an enormously massive cloud of over ten Earth masses of icy debris. Contained within its bounds between the orbits of Caelus and Boreas are innumerable asteroids and comets as well as hundreds of dwarf planetary bodies. The belt is split between a checkerboard of various states which hold shaky dominion over the constantly moving icy bodies.

#### Pluto / Charon / Eris

The most massive system in the Kuiper Belt is the ternary system between Pluto, Charon, and Eris. Pluto and Eris are the two largest objects within the belt, at just over 0.002 Earth masses, and Charon orbits pluto in a tight binary. Eris has a major moon to itself as well, Dysnomia. The system is the center of population in the Kuiper Belt and hosts the headquarters of the Arrokoth Pact, the shaky alliance between the many states of the belt.

#### Haumea

The third largest body within the Kuiper Belt, Haumea is an oddball. Its rapid rotation rate stretches its form into an ovoid, and a thin ring system is clearly visible above its equatorial plane. Haumea, its moons and various nearby asteroids are under the control of Salevaris, a powerful member of the Arrokoth Pact.

#### Makemake

Makemake is notably unpopulated compared to the other large objects in the belt. Its initial colonies and the orbiting Barka Spacedock mysteriously vanished without a trace 79 years ago, and it is still completely unknown why. As such, Makemake's fairly standard resources when compared to the hundreds of other comparable objects have been mostly ignored by the developed nations of the Arrokoth Pact, and the only population there is a tiny camp of ~11,000 people mining out the northern plains.

#### Quaoar

Quaoar is the last remaining colony of the superpowers out here. Under the *de jure* control of the United Nations of Humanity, the Maklotte colony on its surface and its moon Weywot is independent in all but name. Quaoar's seeming normalcy amongst the Kuiper Belt is broken by the presence of an asymmetrical ring system found far beyond the Roche limit, in an orbital resonance with Weywot. It is unknown how this system remains stable.

#### Other Kuiper Belt Objects

There are over 300 potential dwarf planets within the Kuiper Belt, out of almost 4000 known across the system. Most of them are claimed by various nations of the Arrokoth Pact, including Salacia. Beyond the dwarf planets, there are uncountable numbers of smaller bodies, including the site of the signing of the Arrokoth Pact, the bilobate asteroid Arrokoth.

#### The Scattered Disk

The Scattered Disk is the region of the Kuiper Belt beyond the orbit of Boreas, where its density begins to sharply drop off. Almost no one lives here, and the interstellar generation ships sent by the superpowers are the only outposts of civilization beyond it. Objects like Sedna and Leleākūhonua are found here. A subclass of scattered disk objects including Sedna exists, known as *detached objects* or *sednoids*, with periapses far enough beyond Caelus to be unaffected by its gravitational pull.

### Boreas

The outermost planet visited by a living thing, Boreas is a massive, frigid, lonely ball of ice beyond the bulk of the Kuiper Belt. The planet has a small ring system and several moons, and its thin atmosphere of hydrogen gets so cold that it can freeze out over the poles in the winter. Boreas is presently being colonized by a joint effort of the Arrokoth Pact, particularly between Hades, Salevaris, and Trinari.

### Hills Cloud

The Hills Cloud is a vast circumstellar disk interior to the Oort cloud extending from 400 to 25,000 AU from Sol. Substantially denser than the Oort Cloud that encompasses it, it is the primary source of comets in the solar system, as well as being home to almost four thousand dwarf planets and planetary-scale objects. As of the present day, the Hills Cloud and its environs is completely uninhabited, and the *Excelsior* is traversing it on its way to interstellar space.

#### Persephone

The largest object within the Hills Cloud, Persephone is likely a captured rogue planet. It was initially discovered after a pattern was noticed in the orbits of several detached objects within the Scattered Disk that was only explainable by some gravitational force, leading scientists directly to it. Even today, the best image of it comes from Trinari's Albion Deep Space Observatory, showcasing it as a large blue-colored ice giant with at least five large moons and a dusty ring system.

### Oort Cloud

The outermost frontier of the Solar System, the Oort Cloud is a technically unconfirmed spherical region of space extending to the edge of the Sun's gravitational influence containing uncountable numbers of comets. These comets, when disturbed by passing stars or Erebus, are sent inward on million-year journeys to the inner solar system, where they become known to its denizens. It is significantly less dense than the Hills Cloud which it encompasses, and is thought to contain huge numbers of larger objects like dwarf planets and even captured rogue worlds.

## Erebus

Erebus is the single companion of Sol. A dim brown dwarf, it was only discovered near the beginning of the space age by various infrared telescopes, and its three planets were found hundreds of years later with careful measurements of light fluctuations from the object. Erebus' system is notable for its extreme dustiness, a characteristic of much younger systems, implying that Erebus was captured by rather than formed with its partner.

### Kelyra & Kevana

Kelyra and Kevana are the two inner icy worlds of Erebus, orbiting within the system's inner dust disk. They are thought to be icy, with possible subglacial oceans, and are both similar in size to Mars.

### Sardis

Sardis is an enormous world similar in size to Crius, detected via radial velocity and later confirmed with direct infrared imaging. The planet is substantially warmer than the equilibrium temperature at that distance, and is thought to have retained much of its internal heat. Any moons it has are likely affected by enormous tidal heating.