Planets: Difference between revisions
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There are two main categories of '''planets''': [[Terrestrial Planet]]s and [[Gas Giant]]s. Some types of Terrestrial Planets support life or meet the conditions necessary for [[terraforming]]. [[Ships]] equipped with | There are two main categories of '''planets''': [[Terrestrial Planet]]s and [[Gas Giant]]s. Some types of Terrestrial Planets support life or meet the conditions necessary for [[terraforming]]. [[Ships]] equipped with the [[Planetary Approach Suite]] may [[Planetary Landings|land on the surface]] of certain Terrestrial Planets. | ||
The term planet refers to celestial bodies orbiting a [[star]] with a [[gravity]] in a specific range. The gravity of a planet has to be strong enough to hold fluids in a stable state (hydrostatic equilibrium) which prevents them from escaping the planet, and low enough to prevent nuclear processes to start as in stars. | The term planet refers to celestial bodies orbiting a [[star]] with a [[gravity]] in a specific range. The gravity of a planet has to be strong enough to hold fluids and plastic solids in a stable state (hydrostatic equilibrium) which prevents them from escaping the planet and makes the body round, and low enough to prevent nuclear processes to start as in the stars. | ||
Some astronomical objects that meet the official criteria for planet status yet also happen to orbit a planet are instead classified as natural satellites or [[moons]]. When the [[barycentre]] of the planet-moon system falls outside the planet, then both bodies would be considered planets and part of a double-planet system.<ref>https://www.universetoday.com/85749/is-the-moon-a-planet/</ref> | Some astronomical objects that meet the official criteria for planet status yet also happen to orbit a planet are instead classified as natural satellites or [[moons]]. When the [[barycentre]] of the planet-moon system falls outside the planet, then both bodies would be considered planets and part of a double-planet system.<ref>https://www.universetoday.com/85749/is-the-moon-a-planet/</ref> | ||
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|Class IV gas giant | |Class IV gas giant | ||
|Uncommon | |Uncommon | ||
|''Class IV gas giants have primarily hydrogen and helium atmospheres with carbon monoxide and upper clouds of alkali metals above lower cloud layers of silicates and iron compounds, hence | |''Class IV gas giants have primarily hydrogen and helium atmospheres with carbon monoxide and upper clouds of alkali metals above lower cloud layers of silicates and iron compounds, hence the brighter colours. The temperature of their upper cloud layers is typically above 900 K.'' | ||
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|[[File:Gas Giant Class V.png|thumb|center]] | |[[File:Gas Giant Class V.png|thumb|center]] | ||
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|Gas giant with ammonia-based life | |Gas giant with ammonia-based life | ||
|Very Rare | |Very Rare | ||
|''Gas giant with ammonia-based life. This is primarily a hydrogen and helium-based atmospheric gas giant, but a little below the surface cloud layers,life exists based in the ammonia-cloud layer. The chemistry of this gaseous region is far from equilibrium, with a surprising excess of oxygen and many carbon-based compounds giving it some vivid colours. As with many such gaseous living systems, it is underpinned by vast quantities of free-floating radioplankton - tiny carbon-based algae, each retaining small quantity of liquid ammonia, extracting their energy from the intense radiation flux.'' | |''Gas giant with ammonia-based life. This is primarily a hydrogen and helium-based atmospheric gas giant, but a little below the surface cloud layers, life exists based in the ammonia-cloud layer. The chemistry of this gaseous region is far from equilibrium, with a surprising excess of oxygen and many carbon-based compounds giving it some vivid colours. As with many such gaseous living systems, it is underpinned by vast quantities of free-floating radioplankton - tiny carbon-based algae, each retaining a small quantity of liquid ammonia, extracting their energy from the intense radiation flux.'' | ||
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|[[File:Gas giant with water-based life Wredguia EP-K b37-0 4.png|thumb|center]] | |[[File:Gas giant with water-based life Wredguia EP-K b37-0 4.png|thumb|center]] | ||
|Gas giant with water-based life | |Gas giant with water-based life | ||
|Rare | |Rare | ||
|''Gas giant with water-based life. This is primarily a hydrogen and helium based atmospheric gas giant, but not far below the surface exists life based in the water-cloud layer just below the atmospheric surface. The chemistry of this gaseous region is far from equilibrium, with a surprising excess of oxygen and many carbon-based compounds giving it some vivid colours. As with many such gaseous living systems, it is underpinned by vast quantities of free-floating radioplankton - tiny carbon-based algae, each retaining small quantity of liquid water, extracting their energy from the intense radiation flux.'' | |''Gas giant with water-based life. This is primarily a hydrogen and helium based atmospheric gas giant, but not far below the surface exists life based in the water-cloud layer just below the atmospheric surface. The chemistry of this gaseous region is far from equilibrium, with a surprising excess of oxygen and many carbon-based compounds giving it some vivid colours. As with many such gaseous living systems, it is underpinned by vast quantities of free-floating radioplankton - tiny carbon-based algae, each retaining a small quantity of liquid water, extracting their energy from the intense radiation flux.'' | ||
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|[[File:Water Giant.png|thumb|center]] | |[[File:Water Giant.png|thumb|center]] | ||