Imagine visiting a planet where the aliens wear incredibly expensive glass jewelry but they bulldoze tons of diamonds into giant mounds.
We haven’t found such a place. But for the first time an extrasolar planet rich in carbon has been detected that may be chock full of crystallized carbon — diamonds.
The carbon-rich Jupiter-sized planet was first detected last year by the Wide-Angle Search for Planets (WASP) that looks for the shadows of planets passing in front of their stars. The planet, called WASP-12b, is so hot that NASA’s Spitzer Space Telescope and the Canada-France-Hawaii Telescope at Mauna Kea, Hawaii were able to spectroscopically detect the signature of carbon in its atmosphere.
The observations reveal that the planet has more carbon than oxygen and silicates, unlike the chemical abundances on Earth. It’s not impossible the interiors of Jupiter, Saturn, Uranus, and Neptune could have similar carbon/oxygen ratios to WASP-12b, but they are much harder to observe and measure.
Incredible pressures in the interior of gas giant planets could convert carbon into diamonds. A novel twist on this idea appeared in Arthur C. Clarke’s 1997 science fiction sequel “3001: The Final Odyssey.” A gigantic diamond mountain ejected from the core of Jupiter is found on the icy moon Europa.
In 1999 researchers at the University of California at Berkeley made diamond dust from squeezing liquid methane to several hundred thousand times atmospheric pressure.
The international diamond conglomerate De Beers doesn’t have to worry about the market being flooded with an Earth mass worth of diamonds, though. WASP-12b lies 1,200 light-years away and is being consumed by its parent star, as detected in 2010 Hubble Space Telescope observations.
But the Spitzer discovery opened the door to the possibility that our galaxy should contain rocky “carbon planets” with a coal-black tarry landscape perhaps with silicon carbide ceramic-hard outcroppings.
A trip to the local hardware store or car shop illustrates how tough silicon carbide is. Because it is so heat-resistant silicon carbide is used on all types of cutting and drilling devices, and inside motorcycle engines.
The surface of a carbon terrestrial planet would be, well, charcoal black. Carbon compounds would be synthesized by the star’s ultraviolet light. Carbides would be chemically broken apart water to create carbon monoxide and methane rain. Diamonds might literally rain out of the sky after being dredged up from the mantle through volcanic eruptions.
Living on such a planet would be like living in Los Angeles, with nothing but smog and asphalt. Because silicates would be less abundant, glass would be a rare substance.
The gooey carbon-chemistry of life could be miles-deep on such worlds. Despite the lack of water, life might arise in hydrocarbon oceans. Organisms on such a world would be much more exotic that the arsenic-munching Mono Lake bacteria announced last week. There might be creatures that eat silicates or oxides, and use carbon instead of oxygen for metabolism.
If a carbon terrestrial planet is ever discovered, astronomers will be tempted to nickname it “Lucy” after “Lucy in the Sky with Diamonds,” a song from the 1968 Beatles album “Yellow Submarine.” But the lyrics would have to be changed to: “Picture yourself on a methane river, with tarry mountains and carbon monoxide skies.”
Illustation credits: STScI/Bacon, R.Villard