Diamond rain, seas and even "diamondbergs" could be floating inside Jupiter and Saturn, according to new analysis of how carbon behaves at high temperatures and pressures. Neptune and Uranus may already play host to diamonds, so the latest results could mean all of the solar system's gas giants are littered with bling.
"People have been talking about diamonds in Uranus and Neptune for 30 years," says Mona Delitsky of California Specialty Engineering in Pasadena. That's because atmospheric models for these two planets suggest pressure and temperature conditions are extreme enough to crush carbon into diamond, but the picture was less clear for other planets. "For Jupiter and Saturn there was not enough information."
In recent years, however, our knowledge of carbon's behaviour under extreme conditions has been extended by research at places like the Sandia National Laboratories in Albuquerque, New Mexico, which has a machine that can melt diamonds. Delitsky and her colleague Kevin Baines of the University of Wisconsin-Madison have combined data from their research with new models of Jupiter and Saturn's atmospheres and say both planets may have diamonds as well.
The pair say lighting storms on Saturn split methane in the upper atmosphere, producing soot "rain". As the soot falls through the atmosphere and into the gas giant's interior, pressure and temperature increase, which Delitsky and Baines believe crushes the soot particles into diamonds. The diamonds keep on growing as they fall until they are large enough to be called diamondbergs.
Eventually, the mammoth gems would reach regions near Saturn's core where temperatures are a blistering 8000 kelvin and pressures are 500 gigapascals – 500 billion times as great as at Earth's surface – conditions hot enough to melt the diamond.
Delitsky presented the results at the Division for Planetary Sciences meeting in Denver, Colorado today.
Not everyone is convinced. Just because diamonds can exist doesn't mean they do, says Luca Ghiringhelli of the Fritz Haber Institute of the Max Planck Society in Berlin, Germany, who has also questioned the presence of the gems on Uranus and Pluto. It is not clear that an initial diamond nucleus could form to grow into a larger stone, he says. "On Jupiter and Saturn they may melt in the interior, but somebody [would have to] put them there first as there are no conditions for their formation."
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