Earthball

Earthball is the third planetball from the Sunball and the only astronomical object known to harbor life. While large amounts of water can be found throughout the Solar Systemball, only Earthball sustains liquid surface water. About 71% of Earthball's surface is made up of the ocean, dwarfing Earthball's polar ice, lakes and rivers. The remaining 29% of Earthball's surface is land, consisting of continents and islands. Earthball's surface layer is formed of several slowly moving tectonic plates, interacting to produce mountain ranges, volcanoes and earthquakes. Earthball's liquid outer coregenerates the magnetic field that shapes Earthball's magnetosphere, deflecting destructive solar winds.

Earthball'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.

Earthball is an ellipsoid with a circumference of about 40,000 km. It is the densest planetball in the Solar System. Of the four rocky planetballs, it is the largest and most massive. Earthball is about eight light minutes away from the Sunball and orbits it, taking a year (about 365.25 days) to complete one revolution. Earthball rotates around its own axis in a day. Earthball's axis of rotation is tilted with respect to its orbital plane with the Sunball, producing seasons. Earthball is orbited by one permanent natural satellite, the Moonball, which orbits Earthball at 380,000 km (1.3 light seconds) and is roughly a quarter as wide as Earthball. The Moonball always faces the Earthball with the same side through tidal locking and causes tides, stabilizes Earthball's axis and gradually slows its rotation.

Earthball formed over 4.5 billion years ago. Within the first billion years of Earthball's history, life appeared in the oceans and began to affect Earthball's atmosphere and surface, leading to the proliferation of anaerobic and, later, aerobic organisms. Some geological evidence indicates that life may have arisen as early as 4.1 billion years ago. Since then, the combination of Earthball's distance from the Sunball, physical properties, and geological history have allowed life to evolve and thrive. In the history of life on Earthball, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinctions. More than 99% of all species that ever lived on Earthball are extinct. Almost 8 billion humans live on Earthball and depend on its biosphere and natural resources for their survival. Humans increasingly impact Earthball's surface, hydrology, climate, and other life.