Hemisu

Hemisu

Hemisu's supercontinent as seen from space.
Orbital characteristics
Semi-major axis	149598023 km (92955902 mi; 1.00000102 AU)
Eccentricity	0.0167086
Orbital period	224.701 d (0.61520 yr)
Satellite of	Hoku
Physical characteristics
Mean radius	6371.0 km (3958.8 mi)
Surface area	510072000 km2 (196940000 sq mi)
Volume	1.08321×1012 km3 (2.59876×1011 cu mi)
Mass	5.97237×1024 kg (1.31668×1025 lb)
Mean density	5.514 g/cm3 (0.1992 lb/cu in)
Surface gravity	9.807 m/s2 (1 g; 32.18 ft/s2)
Escape velocity	11.186 km/s (40270 km/h; 25020 mph)
Axial tilt	23.4392811°
Atmosphere
Surface pressure	1 atm (100 kPa)

Hemisu is a terrestrial planet located in the Outer Band of the Talin Galaxy. It orbits the orange dwarf star, Hoku. It has three small moons that orbit it. Hemisu offers many biomes such as plains, forests, savannahs, deserts, barren mountains/plateaus, and a vast freshwater ocean. It is comprised of one massive supercontinent and superocean, with one side of the planet being almost entirely land and the other water, with a few major cities and spaceports. It is home to a multitude of animals and plant life. The sentient native species are the Nemeans, lion-like humanoids named after the Nemean lion from Constantian mythology. The planet and its moons are also home to a sizable population of humans, who first settled there in 356 BHT.

Hemisu and its moons are rich in a rare metal ore called etherium that when refined is used in almost everything by the humans that mine it. As such, the surface of Hemisu and its moons are covered in mines and drilling facilities. Due to the many practical uses of refined etherium, it is the most lucrative trade commodity on the planet, and as such is heavily regulated and protected.

Etymology

Hemisu, from the Constanti “hēmisys”, which translates to “half” (temporal and spatial). The humans that settled here named it in reference to Plato’s use of the word for half ἥμισυ (hemisu) much as English refers to one's other half as a partner, but instead referring to the two halves of the planet being a supercontinent and superocean.

Physical characteristics

Size and shape

Hemisu has a rounded shape, through hydrostatic equilibrium, with an average diameter of 12,742 kilometres (7,918 mi), making it the largest planetary sized and largest terrestrial object of the Hoku Solar System, as it is the only planet orbiting Hoku.

Due to Hemisu's rotation it has the shape of an ellipsoid, bulging at its Equator; its diameter is 43 kilometres (27 mi) longer there than at its poles. Hemisu's shape also has local topographic variations. Parallel to the rigid land topography the ocean exhibits a more dynamic topography.

Internal structure

Hemisu's surface is the boundary between the atmosphere, and the solid earth and ocean. Defined in this way, it has an area of about 510 million km2 (197 million sq mi). Hemisu can be divided into two hemispheres: by latitude into the polar Northern and Southern hemispheres; or by longitude into the continental Eastern and Western hemispheres.

Hemisu's ocean covers 47%, or 121,703,421.31 km2 (75,623,000 sq mi) of Hemisu's surface. This vast pool of freshwater is known as the Great Ocean, and makes Hemisu with its dynamic hydrosphere a water world or ocean world. Indeed, in Hemisu's early history the ocean may have covered it completely. The ocean covers Hemisu's oceanic crust, with the shelf seas covering the shelves of the continental crust to a lesser extent. The oceanic crust forms large oceanic basins with features like abyssal plains, seamounts, submarine volcanoes, oceanic trenches, submarine canyons, oceanic plateaus, and a globe-spanning mid-ocean ridge system.

Just over half of Hemisu's surface is land: 53% or 167,946,311.808 km2 (104,357,000 sq mi). The land surface includes many islands around the globe, but most of the land surface is taken by the supercontinental landmass. The terrain of the land surface varies greatly and consists of mountains, deserts, plains, plateaus, and other landforms.

Land can be covered by surface water, snow, ice, artificial structures or vegetation. Most of Hemisu's land hosts vegetation.

The pedosphere is the outermost layer of Hemisu's land surface and is composed of soil and subject to soil formation processes. Soil is crucial for land to be arable. Hemisu's total arable land is 10.7% of the land surface, with 3.3% being permanent cropland. Hemisu has an estimated 16.7 million km2 (6.4 million sq mi) of cropland and 33.5 million km2 (12.9 million sq mi) of pastureland.

The land surface and the ocean floor form the top of Hemisu's crust, which together with parts of the upper mantle form Hemisu's lithosphere. Hemisu's crust may be divided into oceanic and continental crust. Beneath the ocean-floor sediments, the oceanic crust is predominantly basaltic, while the continental crust may include lower density materials such as granite, sediments and metamorphic rocks, as well as an abundance of etherium. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form about 5% of the mass of the crust.

Hemisu's surface topography comprises both the topography of the ocean surface, and the shape of Hemisu's land surface. The submarine terrain of the ocean floor has an average bathymetric depth of 6 km, and is as varied as the terrain above sea level. Hemisu's surface is continually being shaped by internal plate tectonic processes including earthquakes and volcanism; by weathering and erosion driven by ice, water, wind and temperature; and by biological processes including the growth and decomposition of biomass into soil.