Triras

Triras and its large ring system

Triras is the fourth and largest planet in the Arwell System.

## Physical Characteristics

Triras holds the record for being the largest planet in the Arwell System's stellar neighborhood. It also boasts the largest ring system in that region. It has large, clearly defined cloud bands, sometimes interrupted by large storms occasionally brewing cross the planet.

## Atmosphere

Triras has the most striking atmosphere of any planet in the Arwell System. Its atmosphere is composed mostly of hydrogen (H₂) and helium (He). The banded coloration is a result of ammonia crystals in the atmosphere, creating light colored zones with dark colored belts.

## Ring System

Triras has an extremely large and striking set of rings. Scientists believe that it was formed by an unfortunate moon which passed too close to the planet and broke apart, eventually being organized into discrete rings with gaps by gravitational interactions with the remaining moons.

## Moons

Triras has a total of 41 moons, nine of which being major.

* 5 Minor Moons
* Arox
* Hekat
* Minor Moon
* Irvin
* Enkala
* Minor Moon
* Eroa
* Ganamar
* Kalas
* Apet
* Phabus
* 25 Minor Moons

### Arox

Arox is best known for its large crater on the prograde side of the moon. It is also one of the smallest spherical bodies discovered and sits within the largest gap within Triras's rings.

Arox's most notable feature us the Weum Crater, a large crater on its prograde side. It likely formed during Arox's formation, and is one of the older craters on the moon.

#### Biomes

Arox has seven defined biomes.

* Impact Terrain
* Lowlands
* Midlands
* Highlands
* Peaks
* Weum Crater
* Weum Crater Centre Peak

### Hekat

Hekat is an small icy moon of Triras slightly larger than Arox. It has blue cracks across the surface caused by tidal stress from Triras combined with salts from its subsurface ocean. Hekat is also one of the most probable candidates of life in the Arwell System due to the subsurface oceans and cryovolcanic activity.

Arox and Hekat are believed to serve as shepherd moons to Triras's outermost defined ring.

#### Geysers

One of Hekat's most noted features is the presence of geysers on the southern hemisphere. This is a result of tidal forces from Triras breaking open the crust and causing water from the subsurface ocean to rush upwards. Unfortunately, Hekat's subsurface ocean is completely sterile.

#### Biomes

Hekat has a total of eight defined biomes.

* Impact Craters
* Discolored Terrain
* Regular Fractures
* Smooth Icy Surface
* Blue Fractures
* Tiger Stripes
* South Polar Region
* North Polar Region

#### Lagrangian Companion

Notably, Hekat has a lagrangian companion in the form of the small asteroid Meto.

### Irvin

Irvin is the third major moon of Triras and the most volcanic place in the Arwell System. Irvin experiences intense stresses on its mantle due to Triras's gravitational pull, making the moon extremely volcanically active. It is also bombarded by radiation from Triras's Van Allen Belts.

Irvin is a lava world covered in sulfur deposits. Irvin has been found to be the most volcanically active body in the Kerbol System. This is because of the massive tidal forces acting upon the moon from its parent, Triras.

Unlike volcanoes on places like Auster and Teralla, which are primarily silicon based, Irvin's lava flows are made of molten sulfur. As a result, Irvin has a yellow appearance, with more yellow terrain being newer than the older white highlands.

#### Exosphere

Irvin has a tenuous atmosphere hugging the surface consisting mainly of sulfur dioxide (SO₂), with smaller amounts of sulfur monoxide (SO), sodium chloride (NaCl), and atomic sulfur and oxygen. This is caused by outgassing from Irvin's volcanoes.

#### Biomes

Irvin has six biomes.

* Lava Lakes, Flows
* Young Volcanic Terrain
* Volcanic Basin
* Lowlands
* Midlands
* Highlands

### Enkala

Enkala is the fourth major moon of Triras. However, its standing as a major moon is somewhat debatable, as it is smaller than Arox and lacks hydrostatic equilibrium. However most consider it too large to be considered a minor moon. It is a generally dark moon, with only a few craters dotting the surface.

#### Biomes

Enkala has only three biomes, befitting its boringness.

* Lowlands
* Midlands
* Highlands

#### Quasisatellite

Enkala, interestingly, harbors a quasisatellite lingering just beyond its Hill Sphere, Inanis.

### Eroa

Despite its drab appearance, Eroa is among the most interesting moons of Triras. The surface is mostly a dull white, but it is covered in red cracks called lineae. These lineae are also made of ice, but are infused with salts from underground.

Eroa is famous for its theorized subsurface ocean. Tidal forces from Triras allow for the internal mantle of Eroa to be made with liquid water, with more water in the ocean than on all of Auster.

#### Exosphere

Eroa is known to have a faint exosphere, much like the other major moons of Triras. However, Eroa's exosphere seems to be made mostly of oxygen, which can't be stable. This indicates that oxygen is being produced, but we don't know where. It's possible it's created via anaerobic processes, but we have to admit, the possibility of alien life is a tempting thing to say for this famous moon. In addition to oxygen, Eroa's exosphere is also composed of large amounts of carbon dioxide and nitrogen, similar to our atmosphere.

#### Life

Eroa is an icy, barren world, preventing life from existing on its surface. However, tidal forces from Triras allow a deep subglacial ocean to form with plentiful hydrothermal vents peppering the seabed. These are surrounded by all manner of relatively advanced multicellular life forms. Life under Eroa's ice generally has no eyes (or eyes that detect infrared light), and use other means to detect prey and obstacles, such as echolocation or electrolocation.

#### Biomes

Eroa has six biomes.

* Lineae
* Reddish Terrain
* Chaos Terrain
* Icy Lowlands
* Icy Midlands
* Icy Highlands

### Ganamar

Ganamar is one of the more interesting icy moons in the Arwell System. Its surface is a combination of old regions and new regions. The old regions are the darker areas on the surface. They are highly cratered and have a different composition. These regions are composed of more clay-like material instead of ice. The new regions are brighter and are composed mostly of water ice. These spots are cracked and grooved, likely due to tectonic activity.

Ganamar is the largest moon in the Arwell System, at almost half the size of Vitriol and is the only moon with a confirmed magnetosphere. It also may host a subsurface saline ocean, but the concentrations of salt may be too much for the formation of most life.

#### Exosphere

Ganamar has a faint exosphere of oxygen clinging to the surface. This is similar to what is found on Eroa.

#### Life

Ganamar, like all the moons of Triras, experiences strong tidal forces from Triras, heating up the inside. Evidence of a magnetic field around Ganamar as well as gravity scans of the moon indicate that Ganamar likely has a subsurface ocean, similar to Eroa, which could harbor life.

#### Biomes

Ganamar has a total of eight biomes.

* Old Terrain Lowlands
* Old Terrain Midlands
* Old Terrain Highlands
* Young Icy Terrain
* Payne Crater
* Popova Crater
* Impact Craters
* Forer Crater

### Kalas

Kalas is the second largest moon of Triras. It is most recognized for the two massive craters that marked the surface, leaving large pits surrounded by a dangerous region of ridges. Kalas's surface contains some of the oldest rocks in the Arwell System, due to the lack of any geological activity on Kalas. Because of how old these craters are, any new craters formed on the moon will overlap another crater.

Kalas's internal structure appears to be mostly uniform, lacking any well-defined layers. This is likely because the moon formed too slowly for its interior to heat up and differentiate itself.

#### Exosphere

Like other moons of Triras, Kalas hosts a thin exosphere. In this case, the exosphere consists primarily of CO2 being leaked from the surface.

#### Biomes

* Craters
* Collins Impact Structure
* Collins Impact Terrain
* Lowlands
* Midlands
* Highlands
* Everhart Impact Structure
* Everhart Impact Terrain

### Apet

Apet is the largest minor moon in the Triras system and the only minor moon really worth noting. It's a relatively boring space potato physically speaking, but its orbit is what makes it interesting. It has a highly elliptical orbit causing it to travel from beneath the orbit of Irvin to beyond Phabus. No one's sure how it got there or how it's staying in this bizarre orbit, but so it goes.

#### Biomes

Due to its small size, Apet has only two biomes.

* Peaks
* Potatoe

### Phabus

Phabus is the outermost major moon of Triras. It is most well-known for its odd two-faced appearance and its large equatorial ridge. One hemisphere of Phabus is covered in a dark material, possibly caused by a circumplanetary dust excess in its region. This means that part of Phabus's surface has a very low albedo and the rest, being pristine ice, has a very high albedo.

Another odd thing about Phabus is its large equatorial ridge at over 20 km high, making it the tallest mountain structure in the Arwell System. The ridge's origin is unknown.

Phabus's orbit is highly inclined, and appears to be very close to the Arwell System ecliptic, unlike the rest of the Trirasian moon system. It is believed that Phabus is either a captured dwarf planet or a formerly close-in moon that was ejected by gravitational interactions.

#### Biomes

Phabus has six biomes.

* Equatorial Ridge
* Icy Surface
* Material Deopsits
* Prominent Impact Craters
* Small Impact Craters
* Mixed Region