July 25, 2007 — Given enough carbon, pressure and time, diamonds can form — but apparently not everywhere, say researchers who developed new modeling methods to parry the notion that small diamonds could spontaneously form in the skies of giant gas planets like Uranus and Neptune.
The discovery three years ago of a white dwarf star with a solid diamond core bolstered theories that the carbon-containing atmospheres of the large outer planets were celestial diamond factories even closer to home.
"Our simulations indicate that it is extremely unlikely that diamonds could ever have nucleated from the carbon-rich middle layer of Uranus and Neptune," a team of Dutch physicists wrote in paper to be published in Physical Review Letters.
The scientists discovered that carbon atoms in the planets' atmosphere would be much more likely to line up in triangular arrangements, which would yield bits of graphite, not the straight lines more suitable for diamond crystallization, said James Riordon with the American Physical Society.
"People assumed that there were going to be certain combinations that would be suitable" for diamond formation, he said.
