Image: Ron Miller
The study of exoplanets—worlds orbiting distant stars—is still in its early days. Yet already researchers have found hundreds of worlds with no nearby analogue: giants that could steamroll Jupiter; tiny pebbles broiling under stellar furnaces; puffy oddballs with the density of peat moss. Still other exoplanets might look familiar in broad-brush, only to reveal a topsy-turvy realm where rare substances are ordinary, and vice versa.
Take carbon, for instance: the key constituent of organic matter accounts for some of humankind's most precious materials, from diamonds to oil. Despite its outsize importance, carbon is uncommon—it makes up less than 0.1 percent of Earth's bulk.
On other worlds, though, carbon might be as common as dirt. In fact, carbon and dirt might be one and the same. An exoplanet 40 light-years away was recently identified as a promising candidate for just such a place—where carbon dominates and where the pressures in the planet's interior crushes vast amounts of the element into diamond.
The planet, known as 55 Cancri e, might have a crust of graphite several hundred kilometers thick. “As you go beneath that, you see a thick layer of diamond,” says astrophysicist Nikku Madhusudhan, a postdoctoral fellow at Yale University. The crystalline diamond could account for a third of the planet's thickness.
Carbon-based worlds would owe their distinct makeup to a planet-formation process very different from our own. If the composition of the sun is any indication, the cloud of dust and gas that coalesced into the planets of our solar system ought to have contained about twice as much oxygen as carbon. Indeed, Earth's rocks are mostly based on oxygen-rich minerals called silicates. Astronomers have determined that 55 Cancri e's host star, however, contains slightly more carbon than oxygen, which may reflect a very different planet-forming environment. And Madhusudhan and his colleagues calculated that the planet's bulk properties—denser than a water world but less dense than a world made of Earth-like minerals—match those predicted for a carbon planet. The researchers published their findings in the November 10, 2012, Astrophysical Journal Letters.
Life-forms on a carbon planet—if they exist—would little resemble the oxygen-dependent organisms of Earth. Precious oxygen would prove valuable as a fuel in much the same way that humans covet hydrocarbon fuels on Earth, says Marc Kuchner of the NASA Goddard Space Flight Center. Even courtship customs would be worlds apart from ours. “You would not be impressed if someone gave you a diamond ring,” Kuchner muses. “If your suitor showed up with a glass of water, that would be really exciting.”
This article was originally published with the title Diamond Planets.
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29 Comments
Add CommentSad to say, the day may come when a glass of 'potable water' may be worth its weight in gold!
Reply | Report Abuse | Link to thisOn the other hand, if we could send a crew of robots to 55 Cancri e to retrieve a few tons of diamonds, they might become dirt cheap! I understand that quality is critical in determining the values of diamonds, though...
Reply | Report Abuse | Link to thisThere is so much speculation in this article, it can hardly be called "scientific".
Reply | Report Abuse | Link to thisWhile spectral analysis of the star of this planet is very likely to be accurate [stars give off enough radiation to be readily analyzed by a spectrometer], no such luck with the planet.
Thus the whole supposition stems from the fact that the star contains more carbon than most, and as solar systems coalesce from the same package of hydrogen and supernovae remnants, the planet MAY have more carbon most planets.
There has been developed a classification system of planet sizes and densities that would fit exoplanets into theoretical sizes:
Scientists Model a Cornucopia of Earth-sized Planets http://www.nasa.gov/centers/goddard/news/topstory/2007/earthsized_planets.html
It appears the recently discovered planet would fit into the classification of a "pure carbon" planet based on its density measurement.
But this is just one possibility.
It's density could more likely be a sum total of multiple different elements, as long as the total density equaled that of carbon.
(Just look how all the planets in our solar system are different combinations of elements.)
So this article is picked up because of the kooky speculation of "a thick layer of diamond".
Where is science?
Valid points. The article states:
Reply | Report Abuse | Link to this"The researchers published their findings in the November 10, 2012, Astrophysical Journal Letters."
One would have to find a way to access the research report, since there's no direct quotations from it or interviews with the researchers.
Since the only quotations included here are a quip from a postdoctoral fellow at Yale University and some humorous comments from someone who holds some position at the NASA Goddard Space Flight Center, the reader can't really tell what's in the research report. Actually, the latter somewhat made the points of the first commentator and myself - my only excuse is that I was reading only with casual interest...
When did 'science' as you define it and astrophysics ever have more than a nodding acquaintance with each other? Almost entirely theoretical from the very beginning the attempt to replace religious creation myths with a more 'scientific' one can't ever really escape its fundamental self-contradiction. It's a bit late now to start worrying that the lies we tell the children may not be sufficiently consistent!
Reply | Report Abuse | Link to thisWell put!
Reply | Report Abuse | Link to thisA little imaginative speculation is good for scientists. It gives some excitement about what might be out there and sometimes allows disparate thoughts to find links that may later prove to be useful.
Reply | Report Abuse | Link to thisAstrophysics is still a relatively young science. While biology, chemistry, and physics have long histories owing to their prevalence on Earth, astrophysics has only been around for a few hundred years. Astrophysics is also one of the hardest for which to construct experiments as we're on the universe's timetable, not our own. Equating astrophysics to religion is not a valid match as the former is based on observations and measurement and is subject to further observations and measurements, while religion is based simply on faith.
Diamonds aren't really all that rare. Their price is artificially inflated because the De Beers syndicate restricts the flow of diamonds in a sort of single-company cartel similar to OPEC. Tired of paying too much for diamonds? Get rid of the cartel and they'll be relatively cheaper.
Reply | Report Abuse | Link to thisI should've expected that. I do recall seeing something about some big diamond mines opening up in Canada a few years ago, but they've probably joined the syndicate...
Reply | Report Abuse | Link to thisThis isn't meant to be inflammatory, but if that's your view of 'religion' then you've clearly never known faith.
Reply | Report Abuse | Link to thisNot likely. Fresh water might become a rare and valuable commodity, but the earth's surface is two thirds water. It will never be a desert planet. There's no where for all that water to go.
Reply | Report Abuse | Link to thisBesides, once we develop affordable space transportation, water is not particularly difficult to find. Made up of the first and third most common elements in the universe, its the most common compound out there. There's millions of tonnes of it orbiting in the kuiper belt, not to mention other moons and planets in the solar system.
Do you know anywhere I can buy comet water futures?
Reply | Report Abuse | Link to thisArthur C Clark was right!
Reply | Report Abuse | Link to thisNot really. They already have developed graphene sea water filters. Clean water for the world is less than 15 years away.
Reply | Report Abuse | Link to thisThis is precisely what Aaron Swartz was fight for. Open access to publicly funded research papers. Wish I could view the source instead of a few select anecdotal quotes from them. At least now some researchers are posting their papers on-line in his memory wit the marker of #PDFTribute for the general public to see and not have only a select few be able to fully learn and understand the knowledge that it contains.
Reply | Report Abuse | Link to thisSorry, I didn't mean to hijack your discussion and hope I didn't offend. It is just that this topic is important to me and many others out there. Also, since this is a science mind and knowledge based crowd so I figured my digression would be welcomed.
Knowledge and open access to publicly funded research I think is key for everyone. Not just the 'Elite' among universities and labs, but for every citizen of the world.
Oh the pain when you see typos and bad grammar and there is no edit button...
Reply | Report Abuse | Link to thisI appreciate your comment and wholeheartedly agree. As a retiree I can't justify memberships to Science (AAAS), or subscription to Nature or any of the myriad other journals and don't have practical access to a library that does. I'm very pleased with the recent pledge by many journals to migrate to open access.
Reply | Report Abuse | Link to thisI'm not familiar with the #PDFTribute marker, though...
In the field of physics and a few others, you may be aware that many research reports are available in a pre-publication archive database:
www.arxiv.org
For articles such as this one that mention an author by name, such as this one, a reader can search the site by author name: "Nikku Madhusudhan". A list of archived papers is returned in date order; for news reports the desired paper is often one of the first listed - in this case: "A Possible Carbon-rich Interior in Super-Earth 55 Cancri e",
http://arxiv.org/abs/1210.2720
I mention all this just for any readers who aren't aware and are interested. I should also mention that the preprint manuscript may be somewhat different from the final, refereed, publication version.
FYI, this report's abstract provides a great deal of information and perspective that is not contained in this news article:
"... Using such models, the super-Earth 55 Cancri e (mass of 8 Earth masses, radius of 2 Earth radii) has been suggested to bear an interior composition consisting of Fe, silicates, and an envelope (>= 10% by mass) of super-critical water. We report that the mass and radius of 55 Cancri e can also be explained by a carbon-rich solid interior made of Fe, C, SiC, and/or silicates and without a volatile envelope. While the data allow Fe mass fractions of up to 40%, a wide range of C, SiC and/or silicate mass fractions are possible. A carbon-rich 55 Cancri e is also plausible if its protoplanetary disk bore the same composition as its host star, which has been reported to be carbon-rich. However, more precise estimates of the stellar elemental abundances and observations of the planetary atmosphere are required to further constrain its interior composition. The possibility of a C-rich interior in 55 Cancri e opens a new regime of geochemistry and geophysics in extraterrestrial rocky planets, compared to terrestrial planets in the solar system."
There are a number of glaring, Chemistry 101 type errors in this article.
Reply | Report Abuse | Link to this"On other worlds, though, carbon might be as common as dirt. In fact, carbon and dirt might be one and the same." Well guess what dirt is made of carbon on Earth! What a revelation. This author doesn't even know that all life on Earth is composed of carbon, and dirt is simply broken down organisms. Thats why fossil fuels are simply carbon and hydrogen, they are the stored remains of organisms.
How can an author pretend to speak in an educated fashion about life on other planets when he knows less than a high school drop-out about life on Earth.
Here's some perspective:
The most common elements in the universe are (in this order) Hydrogen, Helium, Carbon, Nitrogen, and Oxygen.
The most common elements in your body are Hydrogen, Carbon, Nitrogen, and Oxygen. See any similarities?
This author has literally never spent a day, even a minute, in a biology class if hes speaking about "maybe dirt is made of carbon on other planets", or theorizes life elsewhere may be made of carbon... well duh! We're made of carbon, what an astonishing prediction.
It is clear that the author of this article John Matson is not qualified to be writing about this subject. This is unfortunate because Scientific American is well reputed.
“If your suitor showed up with a glass of water, that would be really exciting.” - Anyone aware of SMART WATER reasons for having high BICARBONATES quantity ????????
Reply | Report Abuse | Link to thiscarbon is not carbon, oxygen is not oxygen, hydrogen is not hydrogen as there is only interference of C/O/H et cetera. What if pure carbon buffered light? Carbon is not carbon,just a signal processing constituent.
Carbon is not very rare on earth. It is found in all living things. The term 'organic' simply means it contains carbon. Life on earth is carbon-based. Oil and natural gas contain carbon. Coal, the most abundant source of electric power, is almost pure carbon. If carbon is so rare on earth, we wouldn't have this global warming hysteria.
Reply | Report Abuse | Link to thisBTW life on earth is not oxygen-dependent. Plants don't need pure oxygen. They need water and CO2.
Dr. Strangelove,
Reply | Report Abuse | Link to thisyou have a strange definition of "not very rare". As pointed out in the article, on a global scale: "carbon is uncommon—it makes up less than 0.1 percent of Earth's bulk"
The mass of the Earth is approximately 5.98×10^24 kg. It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%); with the remaining 1.2% consisting of trace amounts of other elements.
BTW, Water and carbon dioxide are only one part of the cycle. Even plants use Oxygen matabolism.
ed
That wasn't inflammatory... but this was:
Reply | Report Abuse | Link to this"Almost entirely theoretical from the very beginning the attempt to replace religious creation myths with a more 'scientific' one can't ever really escape its fundamental self-contradiction."
I suppose, if you want to take a really simplistic view, you could argue that religious creation myths and astrophysics share the common goal of helping us to understand the cosmos. The difference of course is that religion does not attempt to self-correct based on new evidence. The growth of astrophysics and the greater detail in our understanding has come about as a direct result of our improved ability to gather evidence.
Regarding Leroy's comment: The difference of course is that religion does not attempt to self-correct based on new evidence.
Reply | Report Abuse | Link to thisThis is a generality, and all generalities are wrong. However, not all religions (yes there is more than Christian and Islamic fundamentalism out there.)
Religion doesn't change quickly but it does change. As A Roman Catholic Christian, I and my religion accept the earth is round and revolves around the sun, that live on earth is billions of years old and evolving, and many other facts of modern science. The Church does learn.
Personally, I think some scientific americans should be reminded of a fundamental assumption that comes from the idea of God creating the universe. That assumption is that we can understand the workings of the universe.
That's a key assumption that sometimes gets forgotten in these discussions of religion and science. They are not conflicting studies. They simply ask fundamentally different questions.
Enjoy.
Sorry about not proof reading my previous post. Here's a couple corrections:
Reply | Report Abuse | Link to thisHowever, not all religions (yes there is more than Christian and Islamic fundamentalism out there.) are locked into BC era concepts.
that LIFE on earth is billions of years old and evolving
We already have carbon planets. They're called gas giants. Seriously, folks; hydrogen is vastly more prevalent than carbon in any protoplanetary disk and all that carbon is going to get locked up as methane, blown to the outer edges of the system and sucked up into gas giants.
Reply | Report Abuse | Link to thisValid point.
Reply | Report Abuse | Link to thisThere's a great deal that's not mentioned in this SA article, particularly that the referenced study merely points out that:
"... A carbon-rich 55 Cancri e is also plausible if its protoplanetary disk bore the same composition as its host star, which has been reported to be carbon-rich."
The more complete quote from the paper's abstract (from my comment #17):
"... Using such models, the super-Earth 55 Cancri e (mass of 8 Earth masses, radius of 2 Earth radii) has been suggested to bear an interior composition consisting of Fe, silicates, and an envelope (>= 10% by mass) of super-critical water. We report that the mass and radius of 55 Cancri e can also be explained by a carbon-rich solid interior made of Fe, C, SiC, and/or silicates and without a volatile envelope. While the data allow Fe mass fractions of up to 40%, a wide range of C, SiC and/or silicate mass fractions are possible. A carbon-rich 55 Cancri e is also plausible if its protoplanetary disk bore the same composition as its host star, which has been reported to be carbon-rich. However, more precise estimates of the stellar elemental abundances and observations of the planetary atmosphere are required to further constrain its interior composition. The possibility of a C-rich interior in 55 Cancri e opens a new regime of geochemistry and geophysics in extraterrestrial rocky planets, compared to terrestrial planets in the solar system."
The study's abstract carefully points out that the composition of 55 Cancri e cannot be definitively determined without more complete information...
"A Possible Carbon-rich Interior in Super-Earth 55 Cancri e",
http://arxiv.org/abs/1210.2720
Like politics, religion has no place in a Scientific discussion.
Reply | Report Abuse | Link to thisThere is no proof that a God or Gods exist, and there is no proof that a God or Gods created this Universe.
Scientific experiments clearly show that all physical and chemical reactions occur spontaneously without a God/Gods interceding to trigger them.
The principle of Occam's Razor that given all things being equal, the simplest explanation tends to be the correct one.
Invoking a God/Gods is an intellectual cop out, an excuse for sloppy thinking.
Arguing through analogy, semantics or logic about God's/Gods' existence has never produced any experimentally verifiable data. It's all supposition and make-believe.
Cosmic Carbon-Cycle Conjecjecture:
Reply | Report Abuse | Link to thisPlanets where carbon is as common as dirt,
are post carbon-evolution planets, while those
where carbon is yet very rare, are pre-carbon-evolution-peak planets. -Aiya-Oba (Philosopher).
As I understand, heavier elements like carbon generally tend to increase incrementally with each generation of supernovae, which produce increasingly heavier elements.
Reply | Report Abuse | Link to thisFinding a protostar and protoplanetary disk that largely consisted carbon, to the exclusion of lighter and heavier elements would seemingly require some very exceptional conditions...