Diamond planets

Posted May 08, 2011, at 2:16 p.m.
Last modified May 22, 2011, at 2:03 p.m.


That planets might exist beyond our solar system was regarded as an intuitive possibility for a long time. Then in 1995, there came conclusive measureable evidence: There is a planet orbiting the star Pegasus 51. After that, more verifications followed, 547 as of May 5.

But describing what exoplanets actually might be like is a tricky, sort of dreamy activity. Only 24 have been photographed directly; the rest are detected through numerical data about behaviors of light tens and thousands of light-years distant. Translating the numbers into exoplanetary imagery is a sort of scientific dreamery, and in some ways just as uncertain.

One newly verified planet, WASP-12b, located by the astronomers of the Wide Angle Search for Planets project (hence WASP), appears to have an unusual lot of carbon in its atmosphere. This, the astronomers imagine, implies some odd things.

WASP-12b is about half again as big as Jupiter and orbits the star WASP-12, about 12,000 light-years from us toward the constellation Auriga. Its temperature is more than 4,000 degrees Fahrenheit on the side facing its star, and its orbit is so close (about 2 million miles) that its atmosphere is being flattened into an egg shape and sucked off in a stream into the star.

The astronomers found that there is more carbon than oxygen on WASP-12b, the first time this actually has been measured for a planet, though it had been regarded as a possibility. Where Earth has rock such as quartz and feldspar made of silicon, oxygen and other elements, a “carbon planet” on the other hand would have carbon-heavy rocklike graphite.

But creeping into the range of odd is the possibility that at the right temperatures a carbon planet could have rivers and lakes of oil or tar instead of water, and its rain could be made of methane or gasoline. Even stranger is that upper layers of a carbon planet’s solid core, underneath the gases, could be miles-thick diamond. And so if the crust were unstable, volcanoes could be spilling diamonds out onto the surface, creating diamond mountains.

WASP-12b appears to be too hot to have methane rain or oil rivers. But how many miles of diamond, compressed and cooked from carbon, are under there? Well, no one knows because all the evidence comes from the planet’s atmosphere. It’s hard to get underneath the outer layers of anything, really, and WASP-12b is one of the exoplanets that hasn’t actually been seen; it is detected from light variations measured when it passes in front of the star. Its inner diamond, in other words, is inferred from the shadow it casts.

This kind of shadow-borne technical data is interpreted by logical inferences that turn into imaginations of what an exoplanet’s surface might look like. From the shadows cast by WASP-12b come data that suggest what might be happening under the planet’s clouds. This is not much different from the process a good Jungian psychologist uses to interpret a dream: From out of sleep bubble images that might be signals of what’s happening in the shadows of your unconscious mind.

The extrapolations about the carbon planet are not much more likely to be eternally true than are the extrapolations about the dream. The carbon planet is for now at least too far away for its concrete reality to be verified — and that is a way of describing a dream’s elusive inconcreteness, too. They are for now both imaginary.

And then there’s the fact that scientific wisdom is never perfected. Scientists always are changing their minds about how the universe began, how many stars there are, what’s at work in the center of galaxies. Einstein said intuition is as important in scientific thinking as rational logic. Ideas and insights arise out of long study like bolts of lightning and then vanish as fast as the new data come in, or stay for a while like dew on grass, only to evaporate into morning. Just like dreams, really.

It is tricky going, here in the world where our dreams of other planets originate in facts gathered from starlight. No one knows for sure what’s inside a carbon planet, and to be too certain about it could let you in for being cut to pieces. Which is what might happen if you were somehow able to walk on the diamond planet. That would be a dream worth having.

The astronomers are careful to point out that the existence of diamond planets has not been verified. It’s only a possibility, based now on measurements of obscurations of WASP-12’s starlight. We contemplate this with as few illusions as possible, given these shadows.

Watch for Dana Wilde’s collection of Amateur Naturalist writings, “The Other End of the Driveway,” available in June at


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