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A carbon planet is a theoretical type of planet that contains more carbon than oxygen. Marc Kuchner and Sara Seager coined the term "carbon planet" in 2005 and investigated such planets following the suggestion of Katharina Lodders that Jupiter formed from a carbon-rich core. Prior investigations of planets with high carbon to oxygen ratios C/O include Fegley & Cameron 1987. Carbon planets could form if protoplanetary discs are carbon-rich and oxygen-poor. According to planetary science, it would develop differently from Earth, Mars and Venus, planets made up mostly of silicon–oxygen compounds. The theory has gained popularity and is now said by researchers such as Jade Bond to be built on reasonable ideas, specifically that different systems would have different ratios of carbon to oxygen, and that our own solar system's terrestrial planets actually slant toward being "oxygen planets". The unconfirmed extrasolar planet PSR J1719-1438 b, discovered on August 25, 2011, as well as the planet 55 Cancri e, could be such planets. == Definition == Such a planet would probably have an iron or steel-rich core like the known terrestrial planets. Surrounding that would be molten silicon carbide and titanium carbide. Above that, a layer of carbon in the form of graphite, possibly with a kilometers-thick substratum of diamond if there is sufficient pressure. During volcanic eruptions, it is possible that diamonds from the interior could come up to the surface, resulting in mountains of diamonds and silicon carbides. The surface would contain frozen or liquid hydrocarbons (''e.g.'' tar and methane) and carbon monoxide. A weather cycle is theoretically possible on carbon planets with an atmosphere provided the average surface temperature is below 77°C. However, carbon planets will probably be devoid of water, which cannot form since any oxygen delivered by comets or asteroids will react with the massive amounts of carbon on the surface. The atmosphere on a relatively cool carbon planet would consist of carbon dioxide or carbon monoxide with lots of carbon smog darkening the sky 〔"Kohlenstoffplaneten", SPACE Magazin April 2014 (page.35, in German)〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「carbon planet」の詳細全文を読む スポンサード リンク
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