Silenus

Silenus

Orbital characteristics
Mass (Kg)	1.67E+21
Radius (Km)	459
Solar Day (h)	656
Orbital Period (days)	802
Semi-Major Axis (Km)	2.35E+06
Periapsis (AU)	1.56
Apoapsis (AU)	1.57
Albedo	.11
Surface Temperature (K)	161
Surface Gravity (m/s^2)	.53
Axial Tile (degrees)	0
Inclination (degrees)	13.3
Orbital Speed (Km/s)	21.2
Satellites	None

Named after the mentor and caretaker of the primary god of the Stripping Path and the king of satyrs, Silenus is the third of the moons of Thalassa.

North Polar Regions

A labelled map of the surface of Silenus.

The surface of Silenus, unlabelled.

The North Polar Regions of Silenus are dominated by an extensive cap of bright ice broken by fractures, scarps, enclosed dark basins, and rough frozen uplands. The highest latitudes are covered in thick continuous ice, but the surface is not uniform. Broad cracks, broken margins, and sharply raised icy formations interrupt the cap across much of the northern hemisphere. In several areas, steep clustered ice masses rise above the surrounding frozen terrain, giving the north a rugged and deeply fractured character.

Along the lower edge of the northern cap, the frozen surface gives way to darker exposed ground and cratered transition zones. Isolated impact craters, buried rims, and uneven rocky patches remain visible near the ice margin, while narrow dark belts cut into the polar deposits. The north is defined by the meeting of permanent high-latitude ice and an older, darker crust below.

Equatorial Regions

The Equatorial Regions of Silenus are dominated by dark plains, broad fields of yellow-grey surface deposits, and a major canyon system extending across the middle latitudes. Large stretches of the equatorial belt consist of low-reflectivity terrain interrupted by impact craters, broken escarpments, and long diffuse streaks of lighter material. These lighter deposits are spread across wide plains and basin margins, especially through the central belt, where they form broad sweeping bands over the darker ground.

The most prominent feature of this region is the great canyon system crossing the equatorial zone. It is the largest single, continuous canyon system anywhere in the Atos System. Its main trench runs in a long irregular course through the central and eastern middle latitudes, with branching segments, collapsed walls, and deeply incised margins. Surrounding plains are marked by scattered crater fields and localized rough terrain, while lighter surface material gathers along the canyon approaches and across adjacent lowlands. This equatorial belt contains the broadest uninterrupted exposures of Silenus’s rocky surface and preserves much of its large-scale tectonic and impact history.

Southern Polar Regions

The Southern Polar Regions of Silenus are brighter and more varied than much of the equatorial surface. Broad frozen plains, fractured polar deposits, and broken ice margins extend across the southern high latitudes, with darker rocky uplands and cratered ground rising through the frozen cover in several sectors. The southern cap is irregular rather than continuous, with embedded dark masses, shattered ice zones, and enclosed basins producing a highly broken polar landscape.

The transition from the south polar ice to the darker middle latitudes is especially complex. Ice fills low basins, spreads around exposed ridges, and breaks into broad floe-like masses and fractured sheets near the polar margin. In the southeastern high latitudes, bright disturbed terrain and pale plume-like deposits surround several pits and vents, suggesting localized cryovolcanic or geothermal activity within the frozen southern zone. The south combines permanent ice, fractured crust, and active-looking polar disruption within a single broad glaciated region.

Unusual Qualities

Silenus is known for faint nocturnal luminescence along parts of Valles Silenii, the largest single, continuous canyon system anywhere in the Atos System. During periods of thermal contraction and crustal stress, exposed crystalline seams within the canyon walls are thought to produce weak triboluminescent flashes and electrostatic glow. In the same region, certain wind-cut mineral pillars have earned a reputation as “whispering stones,” producing low harmonic tones when katabatic winds pass through narrow fractures and clustered rock openings.