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gLOSSARY OF TERMS |
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This section attempts to address commonly used terms in the geography section of the site, and elsewhere in this site, articles are in alphabetical order, though the links list should prove the most useful way of locating articles
Cryo-jovian (^top^)
Colloquial name given to star distant jovians in a system, for example Neptune and Uranus are considered to be cryo-jovian. There are no precise defining characteristics of these worlds, but they may have the following features. Composition is dominated by ices, icy mantel accounts for a significant part of planetary volume. Density is relatively high compared to other jovians (+1.20) as they are ice rather than atmosphere dominated They tend to be smaller than ‘main’ jovians, generally being less than 90000km in diameter, their relatively small size reflects the rarified region of their formation. Atmosphere is predominated by hydrogen and helium but also contains more distant ice compounds such as methane and ethane. They tend to produce more heat than they receive from the sun, usually by chemical processes or by the release of latent heat caused by freezing liquids. Tend to have strong magnetic field in common with all jovians, though the field can be generated by ionic conduction in ice mantle or by metallic hydrogen. Ice point (^top^)
A term given to the region around a star where ices can begin to condense out of the solar nebula. There is no one unique ice point for all of the outer system compounds, rather a separate ice point for different ices. Ice points do not preclude these compounds being found further in, rather that they are less abundant, and with the processes of planetary migration and internal chemistry, can transport and create these compounds to regions where they might not be expected, (for example the existence of methane on Earth, which is produced by chemistry rather than collected form planetary formation).
Below is a list of a few ices, and their condensing, or ice points, these values are for sol, for hotter and cooler suns these regions move around a bit.
Ices (^top^)
A name given to low temperature solid compounds that predominate the make up of the outer solar system. This does not only include familiar water ice but also other inorganic ices such as carbon dioxide and ammonia, and also organic ices such as methane and ethane. Ices can also be considered the rocks of the outer solar system, rarely changing from a solid state at the surface, and also mimicking hot rock geological processes such as volcanism and tectonics. Cryo geology is a general name to the study of how ices behave, also cryo-volcanism and cryo-tectonics are used to label fields where ices are considered rather than the more familiar rocky counterparts we see on terrestrial worlds Jovian (^top^)
Describes a world which is generally larger than most terrestrial worlds, and is predominated by ices, or has a very extensive atmosphere of liquid cores. This definition is a very quick and brief summary of the term jovian, though there many different types of jovian planet, and can exhibit a wide variety of behaviour and composition. Jovians are also noted for having thick atmospheres in excess of many bar, generally composed of hydrogen and helium, though not always. This type of planet is considered to be one of the most important determining factors which gives a solar system its shape. Though these planets may not themselves harbour life, their moons can support communities, and their asteroid clearing properties may protect inner terrestrial worlds from bombardment, while outer jovians may encourage the in fall of comets supplying nascent worlds with organic compounds for life. Jovian, migrating/migrated (^top^)
Sometimes during the formation of a solar system a large jovian planet that originated beyond the ice point may start to migrate inwards towards the sun. The reason for this in fall may be due to perturbation by other planets, or the deceleration of the planet in its orbit by solar nebula material. Migrating jovians tend to fling out inner terrestrial worlds as they approach the sun, and the chance of a planet surviving in its orbit while a jovian moves in is low, in this respect a migrating jovian can endanger life, but more often than not the migration happens in early formation, prior to the beginnings of life or even the formation of terrestrial worlds. ‘Young’ migrating jovians, that start to move when the system is young tend also to consume the material of the inner system while they migrate inwards, this also precludes the formation of planets. Pre-existing terrestrial worlds may survive if their orbital plane is significantly different to inward moving jovian, but more often than not the survivors are those that were not flung out system completely and have recovered in the giant planet’s wake, though usually with eccentric orbits. Systems with migrated jovians tend not to have terrestrial worlds, the positions where Earth and Mars are in the human solar system would have been consumed by the migrating worlds, probably before their creation, worlds closer in may have formed before the migration, and if they survive the migration they may retain their original stable orbit, if migration ends before significant perturbation of orbit, or be flung out and recaptures in another orbit. Sometime terrestrial worlds may become satellites of migrating jovians. Terrestrial worlds (^top^)
Worlds whose structure is predominated by rocks and minerals. Though this definition is very brief, terrestrial worlds demonstrate a great range of behaviour and many categories are used to describe them, they are also the predominant cradle for known life in the federation, and all federation races have a terrestrial world as their home.
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