National Geographic News
An illustration of an exoplanet with a diamond crust.

An illustration of 55 Cancri e shows a surface of mostly graphite surrounding a thick layer of diamond.

Illustration courtesy Haven Giguere, Yale

Andrew Fazekas

for National Geographic News

Published October 11, 2012

The universe just got a bit richer with the discovery of an apparent diamond-rich planet orbiting a nearby star.

Dubbed 55 Cancri e, the rocky world is only twice the size of Earth but has eight times its mass—classifying it as a "super Earth," a new study says. First detected crossing in front of its parent star in 2011, the close-in planet orbits its star in only 18 hours. As a result, surface temperatures reach an uninhabitable 3,900 degrees Fahrenheit (2,150 degrees Celsius)—which, along with carbon, make perfect conditions for creating diamonds.

NASA's Spitzer Space Telescope collected data on the planet's orbital distance and mass, and resulting computer models created a picture of 55 Cancri e's chemical makeup.

"Science fiction has dreamed of diamond planets for many years, so it's amazing that we finally have evidence of its existence in the real universe," said study leader Nikku Madhusudhan, a postdoctoral researcher at Yale University.

"It's the first time we know of such an exotic planet that we think was born mostly of carbon—which really makes this a fundamental game-changer in our understanding of what's possible in planetary chemistry."

(See "'Diamond' Planet Found; May Be Stripped Star.")

At only 40 light-years away, in the northern constellation Cancer, the gemlike planet sits relatively near Earth. In dark skies, 55 Cancri e's host star is clearly visible to the naked eye. (See gem pictures.)

Diamond Planet Has Odd Chemistry

The new models fit with previous studies that showed 55 Cancri e's parent star was abundant in carbon—much more so than our sun.

"If we make the assumption that the star and its surrounding planets are all born from the same primordial disk of material, then it makes sense that the entire planetary system would be carbon rich," said Madhusudhan, whose study will appear in an upcoming issue of the journal Astrophysical Journal Letters.

Princeton astronomer David Spergel believes the diamond-planet find probably represents the first discovery of a whole new class of planets whose chemistry has never been encountered. (Related: "'Diamond Planets' Hint at Dazzling Promise of Other Worlds.")

"Unlike our solar system, which is dominated by oxygen and silicates, this planetary system is filled with carbon," said Spergel, who was not involved in the new study.

"While it's still unknown exactly what implication this will have on our understanding of evolution of planetary systems," he said, "there's no doubt it is an important step towards understanding the full diversity of planets."

Billy Cumming
Billy Cumming

Why do some posters automatically presume that because aliens are different then they will presumably want to cause us harm. As humans we are quite capable of inflicting our own harm on ourselves in the guise of - religion, education, science and discovery.

Take religion away from mankind and we will all be better off - so will the aliens!!

I think it is fantastic that a planet has been discovered, and so exotic - ab fab!

Very hard to comprehend a system so alien to us, and almost beyond our imagination apart from those great science fiction writer of the 40s, 50s and 60s.

Stranger in a Strange Land?


It is just so amazing what is actually out there and that if all nations would stop fighting and learn to exist with each other and put their minds together, maybe we could one day discover that there is life elsewhere. The only thing that might unite the earth as we know it, is a real alien attack from another planet, but probably at that point, if they came here to attack, they would be so far advanced on us that we would have no chance anyway. We would all end up as their slaves and work for them in the fields. Some of us would probably be put in concentration camps and killed. Scary S***!!, but something to think about.


Michael Cummings
Michael Cummings

I'm a Christian & a Cummings. You could change your name talking like that. US bending over backward for you or letting you walk on us you telling us being flat to the earth isn't good enough for you while you practice a baby killing religion claiming to help women & minorities is just selfishness, eugenics, & nazism. There is no need to kill you sound like godless selfish Oprah. I am convinced you're really an alien maybe a scout to prepare the way for you unholy godless abominations pardon the pun.


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