Any autonomous self-supporting, self-containing, homeostatic ecosystem. Natural Biospheres - planets such as Earth, Trees, and Eden, are very rare. Most biospheres are artificial, and may be hollowed out asteroids, planetary domes, ships, orbital habs, and so on. Strictly speaking most of these are not spheres, but the original usage has remained. The term was coined by the Old Earth Russian scientist Vladimir Vernadsky in 40 BT (1929 c.e.).