The skies of Jupiter and Saturn may Rain Diamonds
High pressures within the gas giant planets may be sufficient to turn carbon into diamond, according to planetary scientists. They hypothesise that lightning in the upper atmospheres of Saturn and Jupiter zaps molecules of methane, freeing the carbon atoms. These atoms then adhere to each other and form larger particles of soot, which are exposed to greater and greater pressures and temperatures as they fall through the layers of gaseous and liquid hydrogen. The soot is compressed into graphite and then solid diamonds, until the temperature reaches around 8,000°C, when the diamond melts, and potentially forms diamond raindrops.
Read more: http://www.youtube.com/watch?v=wgxQlma-BuU
