Terra Ceralis

Terra Ceralis

Designations
Alternative names	Gaia, Terra, Tellus, the world, the globe
Adjectives	Earthly, terrestrial, terran, tellurian
Orbital characteristics
Epoch J2000
Aphelion	152100000 km (94500000 mi)
Perihelion	147095000 km (91401000 mi)
Semi-major axis	149598023 km (92955902 mi)
Eccentricity	0.0167086
Orbital period	365.256363004 d (31558.1497635 ks)
Average orbital speed	29.78 km/s (107200 km/h; 66600 mph)
Mean anomaly	358.617°
Inclination	7.155° to the Sun's equator; 1.57869° to invariable plane; 0.00005° to J2000 ecliptic
Longitude of ascending node	−11.26064° to J2000 ecliptic
Time of periastron	2021-Jan-02 13:59
Argument of perihelion	114.20783°
Satellites	2 natural satellite: Miakoda >3 300 operational artificial satellites >18 000 tracked space debris
Physical characteristics
Mean radius	6371.0 km (3958.8 mi)
Equatorial radius	6378.137 km (3963.191 mi)
Polar radius	6356.752 km (3949.903 mi)
Flattening	1/298.257222101
Circumference	40075.017 km equatorial (24901.461 mi) 40007.86 km meridional (24859.73 mi)
Volume	1.08321×1012 km3 (2.59876×1011 cu mi)
Mass	5.97237×1024 kg (1.31668×1025 lb) (3.0×10−6 M☉)
Mean density	5.514 g/cm3 (0.1992 lb/cu in)
Surface gravity	9.80665 m/s2 (1 g; 32.1740 ft/s2)
Moment of inertia factor	0.3307
Escape velocity	11.186 km/s (40270 km/h; 25020 mph)
Rotation period	1.0 d (24h 00m 00s) average synodic rotation period (solar day)
Sidereal rotation period	0.99726968 d (23h 56m 4.100s)
Equatorial rotation velocity	0.4651 km/s (1674.4 km/h; 1040.4 mph)
Axial tilt	23.4392811°
Albedo	0.367 geometric 0.306 Bond
Surface temp. min mean max Celsius −89.2 °C 14 °C (1961–90) 56.7 °C Fahrenheit −128.5 °F 57.2 °F (1961–90) 134.0 °F
Atmosphere
Surface pressure	101.325 kPa (at MSL)
Composition by volume	78.08% nitrogen (Template:Chem2; dry air) 20.95% oxygen (Template:Chem2) ~ 1% water vapor (climate variable) 0.9340% argon 0.0413% carbon dioxide 0.00182% neon 0.00052% helium 0.00019% methane 0.00011% krypton 0.00006% hydrogen

Terra Ceralis is the second planet from the Sun. About 29.2% of Terra's surface is land consisting of continents and islands. The remaining 70.8% is covered with water, mostly by oceans, seas, gulfs, and other salt-water bodies, but also by lakes, rivers, and other freshwater, which together constitute the hydrosphere. Much of Terra's polar regions are covered in ice. Terra's outer layer is divided into several rigid tectonic plates that migrate across the surface over many millions of years, while its interior remains active with a solid iron inner core, a liquid outer core that generates Terra's magnetic field, and a convective mantle that drives plate tectonics.

Terra's atmosphere consists mostly of nitrogen and oxygen. More solar energy is received by tropical regions than polar regions and is redistributed by atmospheric and ocean circulation. Greenhouse gases also play an important role in regulating the surface temperature. A region's climate is not only determined by latitude, but also by elevation and proximity to moderating oceans, among other factors. Severe weather, such as tropical cyclones, thunderstorms, and heatwaves, occurs in most areas and greatly impacts life.

Terra's gravity interacts with other objects in space, especially its moons, which are Terra's only natural satellite. Terra orbits around the Sun in about 365.25 days. Terra's axis of rotation is tilted with respect to its orbital plane, producing seasons on Terra. The gravitational interaction between Terra and the moons causes tides, stabilizes Terra's orientation on its axis, and radually slows its rotation. Terra is the densest planet in the Tagorus System and the largest and most massive of the four rocky planets.

Physical characteristics

Size and shape

The shape of Terra is nearly spherical. There is a small flattening at the poles and bulging around the equator due to Terra's rotation. Therefore, a better approximation of Terra's shape is an oblate spheroid, whose equatorial diameter is 43 kilometres (27 mi) larger than the pole-to-pole diameter.

Chemical composition

Terra's mass is approximately 5.97×10²⁴ kg (5,970 Yg). It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminum (1.4%), with the remaining 1.2% consisting of trace amounts of other elements. Due to mass segregation, the core region is estimated to be primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements.

The most common rock constituents of the crust are nearly all oxides: chlorine, sulfur, and fluorine are the important exceptions to this and their total amount in any rock is usually much less than 1%. Over 99% of the crust is composed of 11 oxides, principally silica, alumina, iron oxides, lime, magnesia, potash, and soda.

Internal structure

Terra's interior, like that of the other terrestrial planets, is divided into layers by their chemical or physical (rheological) properties. The outer layer is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovičić discontinuity. The thickness of the crust varies from about 6 kilometres (3.7 mi) under the oceans to 30–50 km (19–31 mi) for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as the lithosphere, which is divided into independently moving tectonic plates.

Beneath the lithosphere is the asthenosphere, a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at 410 and 660 km (250 and 410 mi) below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath the mantle, an extremely low viscosity liquid outer core lies above a solid inner core. Terra's inner core may be rotating at a slightly higher angular velocity than the remainder of the planet, advancing by 0.1–0.5° per year, although both somewhat higher and much lower rates have also been proposed. The radius of the inner core is about one-fifth of that of Terra. Density increases with depth, as described in the table on the right.

Geography

It is estimated that one-eighth of Terra's surface is suitable for humans to live on—three-quarters of Terra's surface is covered by oceans, leaving one-quarter as land. Half of that land area is desert (14%), high mountains (27%), or other unsuitable terrains. States claim the planet's entire land surface, except for parts of Antarctica and a few other unclaimed areas. Terra has never had a planetwide government, but the Ceralis Forum is the leading worldwide intergovernmental organization.

The first human to orbit Terra was [placeholder] on [to be determined. In total, about ? people have visited outer space and reached orbit as of November 2018, and, of these, ? have walked on one of the moons.

Natural resources and land use

Terra Ceralis has resources that have been exploited by humans. Those termed non-renewable resources, such as fossil fuels, are only replenished over geological timescales. Large deposits of fossil fuels are obtained from Terra's crust, consisting of coal, petroleum, and natural gas. These deposits are used by humans both for energy production and as feedstock for chemical production. Mineral ore bodies have also been formed within the crust through a process of ore genesis, resulting from actions of magmatism, erosion, and plate tectonics. These metals and other elements are extracted by mining, a process which often brings environmental and health damage.

Terra's biosphere produces many useful biological products for humans, including food, wood, pharmaceuticals, oxygen, and the recycling of organic waste. The land-based ecosystem depends upon topsoil and fresh water, and the oceanic ecosystem depends on dissolved nutrients washed down from the land. In 2019, 39 million km² (15 million sq mi) of Terra's land surface consisted of forest and woodlands, 12 million km² (4.6 million sq mi) was shrub and grassland, 40 million km² (15 million sq mi) were used for animal feed production and grazing, and 11 million km² (4.2 million sq mi) were cultivated as croplands. Of the 12–14% of ice-free land that is used for croplands, 2 percentage points were irrigated in 2015.