Gentu
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 Gentu and its moon | |||||||||||||
| Designations | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gentǔ, Terra, The World | |||||||||||||
| Orbital characteristics | |||||||||||||
| Aphelion | 152100000 km (94500000 mi) | ||||||||||||
| Perihelion | 147095000 km (91401000 mi) | ||||||||||||
| 149598023 km (92955902 mi) | |||||||||||||
| Eccentricity | ~0.0167086 | ||||||||||||
| 365 d (12.0 months) | |||||||||||||
Average orbital speed | 29.78 km/s (18.50 mi/s) | ||||||||||||
| 358.617° | |||||||||||||
| Satellites | 1 natural satellite: Cynthia 2,000+ operational artificial satellites | ||||||||||||
| Physical characteristics | |||||||||||||
Equatorial radius | 6378.1 km (3963.2 mi) | ||||||||||||
Polar radius | 6356.8 km (3949.9 mi) | ||||||||||||
| Flattening | 0.0033528 | ||||||||||||
| Circumference | 40075.017 km (24901.461 mi) (equatorial) 40007.86 km (24859.73 mi) (meridional) | ||||||||||||
| 510,072,000km2 (316,944,000 mi2) | |||||||||||||
| Volume | 1.08321 × 1012km3 | ||||||||||||
| Mass | 5.97237 x 1024 kg | ||||||||||||
Mean density | 5.514 g/cm3 | ||||||||||||
| 9.807 m/s2 | |||||||||||||
| 0.3307 | |||||||||||||
| 11.186 km/s (6.951 mi/s) | |||||||||||||
Sidereal rotation period | 0.99726968 d (23.934472 h) | ||||||||||||
Equatorial rotation velocity | 0.4651 km/s (0.2890 mi/s) | ||||||||||||
| 23.4392811° | |||||||||||||
| Albedo | 0.367 geometric 0.306 Bond | ||||||||||||
| |||||||||||||
| Atmosphere | |||||||||||||
Surface pressure | 101.325 kPa (at MSL) | ||||||||||||
| Composition by volume | 78.08% nitrogen (N2) (dry air) 20.95% oxygen (O2) 0.930% argon 0.039% carbon dioxide (climate-variable) | ||||||||||||
Gentu, also known as Gentǔ, or Terra, is the third planet from the Sun and the only astronomical object known to harbour life. While large amounts of water can be found throughout the Gentu System, only Gentu sustains liquid surface water. About 67% of Gentu's surface is made up of the ocean. The remaining 33% of Gentu's surface is land, consisting of continents and islands. Gentu's surface layer is formed of several slowly moving tectonic plates, interacting to produce mountain ranges, volcanoes and earthquakes.
Gentu formed over 4.5 billion years ago. During the first billion years of Gentu's history, the ocean formed and then life developed within it. Humans emerged 300,000 years ago and have reached a population of almost 12 billion today. Humans depend on Gentu's biosphere and natural resources for their survival, but have increasingly impacted Gentu's environment. Today, humanity's impact on Gentu's climate, soils, waters and ecosystems is unsustainable, threatening people's lives and causing widespread extinction of other life.