Styx

Styx

Orbital characteristics
Mass (Kg)	2.68E+23
Radius (Km)	1,925
Solar Day (h)	48
Orbital Period (days)	2
Semi-Major Axis (Km)	356,801(km)
Periapsis (AU)	.002
Apoapsis (AU)	.002
Albedo	0
Surface Temperature (K)	147
Surface Gravity (m/s^2)	4.84
Axial Tile (degrees)	2.4
Inclination (degrees)	0
Orbital Speed (Km/s)	6.34
Satellites	None

Styx is the first of the three major moons of the planet Thalassa.

North Polar Regions

A labelled map of the surface of Styx.

The surface of Styx, unlabelled.

The North Polar Regions of Styx are dominated by a fractured and uneven ice cap that rests upon older, darker terrain. Unlike a uniform polar sheet, the northern ice is broken by deep fissures, exposed rock, and irregular uplands, producing a sharply divided boundary between frozen and uncovered ground. Along the northwestern transition, the rugged highland system known as the Kethar Marches forms one of the most unstable regions of the polar boundary, where ice fractures into jagged shelves and exposed ridges.

South of this boundary, the large enclosed depression called the Phoenor Basin marks one of the most prominent northern basins, its dark interior standing in contrast to the surrounding frost. Nearby, the elevated circular formation known as the Acheronax Crown rises above the surrounding terrain as one of the defining structures of the northern hemisphere. To the east, the boundary zone termed the Nyxis Verge marks the transition into more broken and partially uplifted terrain, where the polar ice gives way to the darker and more varied equatorial belt.

The northern hemisphere is therefore characterized by fragmentation and threshold conditions. Ice and exposed ground interlock across a landscape shaped by stress, collapse, and long-term erosion. The Kethar Marches, Phoenor Basin, Acheronax Crown, and Nyxis Verge together define a region where surface and depth meet in unstable equilibrium.

Equatorial Regions

The Equatorial Regions of Styx form the most visually complex portion of the moon, dominated by dark plains interwoven with sweeping fields of lighter material. These pale deposits spread across the central belt in broad, irregular patterns, creating a stark contrast with the underlying low-reflectivity terrain. This central province is collectively known as the Stygion Expanse, the defining region of Styx’s surface.

Within this expanse, several major structures organize the terrain. The broad transitional zone called the Velion Reach occupies part of the central belt, where lighter deposits merge with darker plains. To the east, the large volcanic-like depression known as Anagen Patera stands out as one of the most prominent caldera structures, while the adjacent boundary known as the Genor Threshold marks a sharp transition into more fractured terrain.

Across the western equatorial zone, the elongated trench system known as the Kathar Chasma cuts through older terrain, forming a deep and continuous corridor. South of this, the wide lowland called the Metraxis Plain extends across a region of darker ground interspersed with lighter deposits, while nearby enclosed depressions such as the Thyrix Hollow and the broader Acherel Basin provide localized zones of accumulation and shelter.

Farther east, the branching fracture system known as the Morvaxis Fossae spreads across the terrain in a network of broken ridges and troughs, reinforcing the fractured nature of the equatorial belt. Together, the Stygion Expanse, Velion Reach, Anagen Patera, Genor Threshold, Kathar Chasma, Metraxis Plain, Thyrix Hollow, Acherel Basin, and Morvaxis Fossae define a landscape of layered deposits, structural instability, and continual transformation.

Southern Polar Regions

The Southern Polar Regions of Styx are covered by an extensive but irregular ice mass, more fragmented than the northern cap and interspersed with exposed terrain. The ice spreads across lower latitudes in uneven sheets, filling depressions and extending into surrounding lowlands while leaving higher ground partially uncovered. Along the southwestern region, the pale drift field known as the Serakon Drift forms a broad zone of redistributed material, where frost and fine deposits gather across the surface.

Toward the southern interior, the boundary between ice and exposed ground becomes increasingly complex. The broad frozen expanse known as the Nemoris Shelf marks one of the most continuous regions of southern ice cover, while nearby geothermal or altered terrain is suggested by the darker and more irregular region of the Velkar Fumaroles. Cutting across this transition zone, the elongated corridor called the Kalyth Passage forms a natural route through the southern terrain, linking multiple basins and fractured regions.

At the far southeastern edge, the feature known as the Velthys Scarp defines a sharp boundary between the ice-dominated southern region and the darker underlying crust. The southern hemisphere is therefore shaped by gradual transition rather than abrupt division, with ice, rock, and fractured terrain combining into a landscape defined by persistence and slow change.

The Serakon Drift, Nemoris Shelf, Velkar Fumaroles, Kalyth Passage, and Velthys Scarp together define the southern regions as a zone of accumulation, erosion, and emergence, completing the geography of Styx as a world shaped by descent, fragmentation, and the veiled transformation of its surface.