Astronomy column: It's raining diamonds on Jupiter

The creation of diamonds on Jupiter and Saturn starts when lightning storms high in the atmosphere break methane into carbon dust which falls into layers of the atmosphere with increasing pressure and hardens into chunks of graphite, which then become diamonds at even greater pressures.
BY WAYNE HARRIS-WYRICK Published: November 5, 2013
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If diamonds are a girl's best friend, then Jupiter just might be a girl's favorite planet.

Diamonds form naturally deep below the surface of our planet. The high heat and pressure there breaks down deeply-buried methane, a gas composed of carbon and hydrogen. The carbon atoms then align to create graphite — the lead in your pencil — then compresses further to become diamond. Both graphite and diamond are forms of pure carbon with different arrangements of the carbon atoms.

Most laboratory-created diamonds used for jewelry are created by a different process, called chemical vapor deposition. The process, developed in the 1980s, offers simplicity and flexibility for jewelry production. Necessary temperatures are relatively low, and the diamonds can form at pressures about half of Earth's normal atmospheric pressure. This method involves feeding carbon-containing gases into a chamber and zapping them with electricity to break the gasses down. The diamonds essentially grow atom by atom as carbon atoms stack up with other carbon atoms.

The first laboratory-created diamonds essentially mimicked what Earth does naturally. Using a tiny diamond as a seed, the necessary raw materials were mixed in a kind of vice, heated to around 2,700 degrees Fahrenheit and a pressure 50,000 times greater than Earth's standard atmosphere pressure. This is still the cheapest way to create diamonds in a laboratory, but the diamonds produced this way tend to be best suited for industrial purposes.

Both Jupiter and Saturn make diamonds using a combination of these two processes. Both planets contain significant amounts of methane in their atmospheres. The creation of diamonds on both planets starts when lightning storms high in the atmosphere break the methane into soot — carbon dust — which falls into layers of the atmosphere with increasing pressure and hardens into chunks of graphite, which then become diamonds at even greater pressures.

In Jupiter, the biggest of the diamonds would be more than a quarter of an inch diameter, “big enough to put on a ring, although, of course, they would be uncut,” Kevin Baines, of the University of Wisconsin-Madison and NASA's Jet Propulsion Laboratory, said.