Planets: Difference between revisions
m Added a link |
m Added links and references |
||
| Line 1: | Line 1: | ||
There are three main categories of '''planets''': Solid planets, water giants and gas giants | There are three main categories of '''planets''': Solid planets, water giants and gas giants. | ||
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 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. | ||
Some astronomical bodies, we call planets, are not considered as planets by this definition. [[Moons]] are natural satellites orbiting a planet and do not fall into the category of planets. However, some natural satellites are considered as planets because they fit their definition. | Some astronomical bodies, we call planets, are not considered as planets by this definition. [[Moons]] are natural satellites orbiting a planet and do not fall into the category of planets. However, some natural satellites are considered as planets because they fit their definition.<ref>https://www.universetoday.com/85749/is-the-moon-a-planet/</ref> | ||
== Terrestrial planet == | == Terrestrial planet == | ||
| Line 166: | Line 166: | ||
|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 small quantity of liquid water, extracting their energy from the intense radiation flux. | ||
|} | |} | ||
[[Category:Planets]] | |||
== References == | |||
<references />[[Category:Planets]] | |||
[[Category:Celestials]] | [[Category:Celestials]] | ||
{{Stub}} | {{Stub}} | ||
[[Category:Guides]] | [[Category:Guides]] | ||