ENCYCLOPEDIA GALACTICA Edition 428193 - Earth English Definition: 'Green World' A Language English1 expression pertaining to an Earth-like planet2 whose hue is green or mostly green rather than blue.3 This phenomena is a consequence of elevated water ice content – from two (2) to four (4) percent - in the upper atmosphere of such a planet. Ice crystals scatter green light over top of the blue wavelengths dispersed by atmospheric nitrogen. Depending upon abundance, planetary hue may be completely green or shift from blue at disk centre to green at the limb. On the surface of such worlds, horizons will appear green whereas the zenith may transition to blue or turquoise. The horizon may also display regular lightning discharges caused by the heightened ice content in the atmosphere. These bodies are also known as “Cool Earths” or “Ice Earths” or by comparable translations. Most green worlds orbit near or just beyond the outer edge of their star's temperate zone.4 As a result, the global temperature is colder than Earth by five (5) to ten (10) degrees celsius (oC) and is the reason for the increased ice content in the upper atmosphere.5 Yet green worlds are warm enough to retain liquid surface water within starward regions of the planet – normally the equitorial and sub-equitorial bands. Undersea volcanism and plate tectonics can also factor into maintaining liquid surface water the further out a planet is found. And it is not uncommon for ocean currents to disperse warm (and saline) waters into the colder climates. Deep oceans can be liquid beneath the polar caps just like the Arctic Ocean on Earth.6 Being Earth-like, most green worlds are life bearing or have the potential for life. But the biosphere of a green world is prone to periodic ecological collisions.7 Not all land masses are considered fixed, some are known to be afloat upon giant, ancient icebergs. These “islands” masquerade as land masses complete with evolving topography and local ecologies. Floes have been found to grow in excess of one (1) million (106) square kilometers (km2) in area – the size of Patagonia – as a single mass or as a cluster. And like all icebergs they drift in the ocean currents to periodically collide with other burgs or fixed masses. These collision events will abruptly introduce foreign species into otherwise isolated habitats and upset the local ecological balance. Micro-extinctions are common but this promotes the selection of robust and adaptive species. Cumulatively, ecological collisions do not always disrupt or curve natural selection away from complex or specialized lifeforms or even intelligences. Planet Ara (EGO 0601-00000000109) and its eco-engineered teressëa (EGO 0601-00000000112) are examples of inhabited green worlds supporting a common technical civilization.8,9 Albeit, Civilization Ara emerged from within the oceans of Planet Ara instead of on land. Although bodies described as green worlds are often displayed as visual representations of the 'green world' in modern Chromatic spiritualism, the two concepts are not equivalent or related.10 Notes: EGO: Encyclopedia Galactica Object See references: 1Civilization Humanity: Linguistic Types 2Planet Earth: Essential Characteristics For Species Habitation 3Civilization Humanity: CIE Colour Chromaticity Table 4Definition: 'Temperate Zone' 5Civilization Humanity: Scientific Standards 6Planet Earth: Polar and Sub-Polar Regions 7Definition: 'Ecological Collision' 8Definition: 'Teressëa' 9Civilization Ara: History 10Civilization Humanity: Spiritualism, Mythology