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It is our general understanding of solar system composition that planets fall into two categories: gas giants like Jupiter, Saturn, Neptune and Uranus… and rocky bodies that support some type of atmosphere like Earth, Mars and Venus. However, as we reach further into space we’re beginning to realize the Solar System is pretty unique because it doesn’t have a planetary structure which meets in the middle. But just because we don’t have one doesn’t mean they don’t exist. As a matter of fact, astronomers have found more than 30 of them and they call this new class of planet a “Super-Earth”.
“Super-Earths, a class of planetary bodies with masses ranging from a few Earth-masses to slightly smaller than Uranus, have recently found a special place in the exoplanetary science.” says Nader Haghighipour of the Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii. “Being slightly larger than a typical terrestrial planet, super-Earths may have physical and dynamical characteristics similar to those of Earth whereas unlike terrestrial planets, they are relatively easier to detect.”
Having a super-Earth in the neighborhood opens the avenue towards habitability. Chances are planets of this type have a dynamic core and are able to maintain a type of atmosphere. When combined with being within the habitable zone of a host star, this raises the bar towards possible life on other planets.
“It is important to note that the notion of habitability is defined based on the life as we know it. Since Earth is the only habitable planet known to humankind, the orbital and physical characteristics of Earth are used to define a habitable planet.” says Haghighipour. “In other words, habitability is the characteristic of an environment which has similar properties as those of Earth, and the capability of developing and sustaining Earthly life.”
But being a super-Earth means that there is a lot more going on than just being in the zone. To qualify it must meet three requirements: its composition, the manifestation of plate tectonics, and the presence of a magnetic field. For the first, the presence of liquid water is a high priority. In order to determine this possibility the values of its mass and radius have to be known. To date, two super-Earth planets for which these values have been determined – CoRoT-7b and GJ 1214b – have given us fascinating numerical modeling to help us better understand their composition. Plate tectonics also plays a role through geophysical evolution – just as the presence of a magnetic field has been considered essential for habitability.
“Whether and how magnetic fields are developed around super-Earths is an active topic of research.” notes Haghighipour. “In general, in order for a magnetic field to be in place around an Earth-like planet, a dynamo action has to exist in the planet’s core.”
Last, but not least, comes an atmosphere – the “presence of which has profound effects on its capability in developing and maintaining life.” From its chemical properties we can derive the “planet’s possible biosignatures” as well as the chemicals which formed it. Atmosphere means environment and all of this leads back to being within a habitable zone and of sufficient gravity to keep atmospheric molecules from escaping. Says Haghighipour, “It would not be unrealistic to assume that super-Earths carry gaseous envelopes. Around low-mass stars, some of such atmosphere-bearing super-Earths may even have stable orbits in the habitable zones of their host stars.”
Has a super-Earth been detected? You betcha’… and studied right down to its spectral signature. “The recently detected super-Earth GL 581 g with its possible atmospheric circulation in the habitable zone of its host star may in fact be one of such planets.” says Haghighipour. “More advanced telescopes are needed to identify the biosignatures of these bodies and the physical and compositional characteristics of their atmospheres.”
Further Reading: Super-Earths: A New Class of Planetary Bodies.
What an amazing article. Thank you..
is Gliese 581 g not a unconfirmed Extrasolar planet?
I think you remember it very well.
I think you remember it correctly.
Anyway, was my comment deleted? I posted this yesterday. What is going on?
When you think of how many super earths will be discovered in the future, i find it laughable that some people still dismiss life on other planets.
When you think of how many super earths will be discovered in the future, i find it laughable that some people still dismiss life on other planets.
When you think of how many super earths will be discovered in the future, i find it laughable that some people still dismiss life on other planets.
There are sceptical people saying it’s just one intelligent life per galaxy cluster. Not very effective for the universe, life’s getting owned, haha.
And here we go again, the phrase “life as we know it”. Super annoying. It’s like we are super dumb and moving life couldn’t use other elements. Let’s keep this phrase for million years into the future when searching for living clouds of dark matter in the 5th dimension.
And here we go again, some opinion on “life as we know it”. Which is, in fact, “super-annoying”. 😀
It is the key descriptor of astrobiology research, because our case study have it and we can look for “perturbances around the state”. It is also, because we have only one case, important that it is a priori likely – water+CHNOPS is ubiquitous.
If we had a firm abiogenesis theory, it would instead be interesting to look at extreme cases suggested by it. Alas, that is not yet the case, hence the heuristic only research strategy.
But we should also mind that this is not a closed window, since main habitability/inhabited observables are independent of it.
– We can in principle observe atmospheric chemistry imbalances regardless of chemistry.
This is why IMHO Titan’s two-three imbalances (low atmosphere deficit of hydrogen but surplus of acetylene), also the fact of methane long time balance, is stronger indication of something interesting than Mars sole methane (which is arguable to boot). It may not be life, but it _is_ interesting.
– We can in principle observe clouds (on nearby planets) regardless of chemistry, by absorption (IIRC) effects.
– We can in principle observe oceans, continents and continent sized forests (on nearby planets) regardless of chemistry, by scattering (IIRC) effects.
Yes, from certain perspectives (open minded; sci fi) it is annoying. From a research perspective (knowledge minded; practical) it is understandable, and it is the seemingly irrelevant opinion on science which is annoying.
I post 3 lines and you come up with long article. 😀
So you straight-on believe in living dark matter clouds, living planets or ghosts rather than more realistic creatures on other planets??? 😀
There was an article about other possible chemistries of alien life. If it’s possible it will happen. And now, what we don’t know about them? How do they poop or what? Why not keep it simple for masses? Of course, if they have a different chemistry/biology, they also have different habitability requirements. Also, I think it should be called human habitability or earth life habitability.
Imagine Ivanman shouting at UFO, oh look, life as we don’t know it.
It really is sparking imagination in the wrong way. Science could just call it other possible life or aliens. If it’s not possible, why mention it? If you believe in ghosts, it’s too far away to even mention it.
Really, tell me what is your belief or prediction. What kind of creatures do you expect and when we will be able to find them?
“So you straight-on believe in living dark matter clouds, living planets or ghosts rather than more realistic creatures on other planets??? :D”
This is just my own personal opinion but I think that until we have a better understanding and/or definition of what “life” actually is…including as it relates to ourselves and the creatures that share this planet with us (or as Torbjorn puts it, “abiogenesis theory”, I think that the possibilities for life are as vast as the universe itself. The question I believe as it pertains to this part of the discussion is “Would we humans recognize it?”
Let’s consider those “living dark matter clouds” for a moment? Do I believe in them? I dunno…does the cloud believe in me? -If- such an “entity” (for lack of a better word at the moment) were able to perceive us and for whatever unimaginable reason were to try an initiate some form of contact, would we humans perceive it as generally anything other than smog or fog or a cloud? With our own rather limited perceptions, what would be the chance of anyone truly recognizing such a thing as “life” and further, what would be the chances of anyone else believing said person if they tried to tell others what they saw, felt or experienced? Be honest here…people who believe in ghosts are usually nothing more than crack pots with over-active imaginations, right? RIGHT?? In the instance of the cloud, would our own limitations and perhaps even our own ignorance make it any less alive from it’s own point of view? If I were the cloud, I think I might be rather offended by that 🙂
As far as a “living planet” goes, there are those who have believed for a great many years that the planet WE live on is “alive” and there has even been some recent evidence to suggest that this is very possible…from a certain perspective at least. Is this life “as we know it”? Hhhhmmmm……..
While it may be rather rhetorical, I think the expression “life as we know it” is rather self-explanatory and pretty necessary if for no other reason than because it at least suggests that there COULD be other life out there that we are totally unable to perceive….doesn’t mean it isn’t there, just means we can’t bear witness to it.
Again, just my own opinion. I’m gonna go talk this over with my cat now and see what he has to say about all of it……
So, what’s the point of talking about life that we can’t recognize? And maybe never will? We don’t have any hints yet. Like I said too soon to whore it.
Living planet. So, there is an evidence that I’m telepathically connected with flowers??? 😀 And we are having subconscious war together with flowers telepathically against Martian living dark matter clouds. What’s the point?
I think that the phrase ‘life as we know it’ is pretty redundant and annoying. Life is simply life. No need to define it. People will find proper words for whatever they find interesting. It will sort itself out.
I already described the current research perspective above.
It’s funny that now I get just one sentence.
If we had a firm abiogenesis theory, it would instead be interesting to look at extreme cases suggested by it.
——
It’s a bit of a chicken/egg problem, isn’t it? Without observing another data point of life arising in the universe, it’s difficult to have a firm abiogenesis theory. And without a firm abiogenesis theory, we can only speculate on what other forms life can take.
Though one other bit of data pointing to the idea that exo-life might be “sorta as we know it” is the fact that amino acids have been found in comets and asteroids. The main difference might just be chirality – perhaps one day we’ll find life very similar to ours but made entirely of right-handed aminos.
If by chicken vs egg you mean which was the first to be ‘different’ from the earlier progenitor that would have to be the egg, if the progenitor did not have that mechanism for a developing fetus. (grin)
I wish to make it clear from the outset that I am opposed to labeling any microbe, molecule, or compound as right OR left, I want that in the record right now.
I hope my esteemed colleagues can take note of this preference and not belabor any type of favoritism to the handedness of our amigos, I mean aminos, since there is plainly an effort to obdurate… er um, obfuscate — I say, it is plainly… er um, plain as the beak on our face!
I, too, wish to welcome out galactic overlords into our bosom, and hope they take pity on our plight and serve us as we have served others.
Yoke, yoke I say… All in jest folks, really.
Mary
If by chicken vs egg you mean which was the first to be ‘different’ from the earlier progenitor that would have to be the egg, if the progenitor did not have that mechanism for a developing fetus.
I do. And you’re right – the answer is “egg,” since oviparity predates the hybridized junglefowl by several hundred million years.
Interesting summary. But the hook of our solar system lacking super-Earth is not so convincing, since the mass/radius pattern fits Kepler’s distributions. Rather we would like to know why super-Earths goes on become Neptunes and Jupiters (if that is what happens).
It is entirely possible that some of these super-Earths could harbor life. In fact the larger the planet is the higher the envelope for complexity. The case is somewhat evident with Earth vs Mars.
LC
It is entirely possible that some of these super-Earths could harbor life. In fact the larger the planet is the higher the envelope for complexity. The case is somewhat evident with Earth vs Mars.
LC
Why? How it would be more complex that life on Earth? And I don’t see how it is evident with Earth vs Mars…
The bound on the amount of information a system can hold is determined by the area of the structure. This has a certain relationship to black holes, where the Bekenstein bound indicates that the entropy of a black hole is given by the horizon area A as
S = kA/4L_p^2
for L_p the Planck length L_p = G?/c^3 and k the Boltzmann constant. The area A is given by integer units of Planck areas A_p = 4?L_p^2, so A = NA_p and the entropy is S = k N. This fits in well with the equipartition results in statistical mechanics.
Now for less extreme systems there is a scaling rule from this. For systems where elementary units of information are contained in atoms or molecules we scale this up from the Planck length to that of the atomic size 10^{-8}cm or one Angstrom. So a system which scales its volume up with mass scales its surface area by M^{2/3}. This is why we do not expect to find protistan life forms, such a paramecia and amoeba, with the complexity or intelligence of a human being or any comparably sized animal. We also do not expect to find an asteroid of 10km radius with some microscaled biosphere on its surface. The asteroid Vesta clearly shows no such structure. When we scale up to the moon again we do not find anything like that. Mars is then large enough to where some level of complexity required for life might emerge.
For a planet twice the mass of Earth there is a 1.6 times the amount of entropy or information possible. Again information is related to the statistical occurrence of a bit p(n) by
S = -k sum_n p(n)log[p(n)]
Which is S = k log(N) for N bits with equal probability p(n) = 1/N for all n. So with a higher entropy possible and with conditions appropriate it is not unreasonable to think that such a planet might have a very highly complex biosphere. Of course just because the entropy possible (entropy bound) is higher it does not automatically mean there are more complex structures or life forms.
LC
By the same (or at least similar) logic, a land area twice the size of another will see higher complexity in its biosphere, all other things being the same.
This may very well be true, but I would imagine there are other, much more influential considerations, such as climate and the positioning of continents.
But evolution uses very little entropy compared to growth from using solar energy.
Conversely, what constrains cellular complexity is the energy production of the cell. An eukaryote has access to ~ 10^5 times as much energy for protein turnaround compared to prokaryotes due to mitochondria. (It is late; please google Lane et al for refs.)
It is the cellular constraint of turnaround that decides the maximum extent of genome complexity. Super-Earths will not have m,ore complex life.
In fact, since the gravity means smaller and less functional organisms (no flight, say), they will likely be simpler.
The planets will be larger, so they should have more diversity and larger ecology. Again, not from a scaling rule, but from how evolution works.
Why all this fear of being alone in the universe?
When ever anything is mentioned about other planets, we get all this crap about possible life on other worlds. Let’s face it, there is no one out there, not a whisper, nothing. We’ve been listening and no one has sent us a postcard or even a simple message. Sorry people but you are all deluding yourselves. If we find microbes on Mars it means nothing but probable contamination from the Earth. We are alone in a big Universe….there are no aliens…..no UFO’s….nothing at all but our sad imaginations. Get a grip and deal with it!
A) i don’t really think this is a reasonable thing to (apparently) get all mad about
B) that’s your opinion and you’re welcome to it, but the argument you’re making (they haven’t contacted us in the 60 or 70 odd years we’ve been listening, so it’s impossible that there’s life out there anywhere) has too many flaws to mention, so don’t be surprised if people don’t take it too seriously.
I take ezlab very seriously. It is the flaw in the ointment i object to, as I would object to someone kicking sand all over my freshly oiled body as they dive for a beach ball.
The flaws of his argument aside, he makes the same points made often in the past 10,000 years of recorded history. We do have delusions and sad imaginations as our history shows us to this day. We also have illusions from our imaginations — some of us at least, like mirror in the heavens guy, and he is obviously not the only one, there are a myriad.
“…you are all deluding yourselves.”
“…nothing at all but our sad imaginations.”
But he stops short of the natural end to his and others point, we also have brain and logic, facts and surmise and these are not a fallback, these are our stock in trade. These tools indicate to us a different view of the universe than his rather grim view. If after a fair test we find there is no one close enough to talk across the fence with, indeed, no one at all that we can communicate with on any level. Then we might need to have his view as the fallback and move on from there.
Mary
I agree that his rather pessimistic view of human imagination versus historical reality is a point well worth considering.
Luckily enough, as we have discussed here countless times, astrobiology is a field with plenty of possibility. Our past science fiction musings on extraterrestrial life may be wrong; but I look forward to the surprises.
I do not share such a negative outlook either.
What a bleak, depressing worldview. Or universeview, if you will.
This planet has been capable of sending and receiving radio signals for just over 100 of the 4.57 billion years of its existence. We’ve been doing active SETI for half of those years, and the first of our broadcasts to reach a destination will not do so until 2029. We’ve also been doing passive SETI for the same amount of time, listening to a limited number of signal ranges from a limited number of locations in a inconceivably vast region of one galaxy.
Concluding that there is no life out there because we’ve found no evidence during the cosmic blip of our technological existence is beyond ludicrous. It’s the equivalent of moving to a new house and concluding that your neighborhood is deserted because nobody has stopped by to offer you pie.
The good thing about the “we are alone” viewpoint is that it’s impossible to prove and easy to disprove. It can never be proven with certainty that we’re all alone in the mind-boggling infinity of the universe. But one self-replicating prion on Titan proves that we’re not alone.
You can keep your Fermi paradox. I’ll stick with the optimistic viewpoint.
1.) Your comment arrogantly assumes that there MUST be something special about “us” that would give anyone else out there a reason to contact us. We’re still a very primitive and backwards culture who kill each other over petty issues such as politics and religion…a people that hasn’t even learned to take care of it’s own planet yet. Why would -anyone- go out of their way to contact us?? What exactly would be the point?
2.) You assume that anyone even KNOWS we’re here when signals from our own planet have only recently reached our next nearest star. Why should anyone know we’re here even -if- they had a desire to communicate?
3.) You assume that we as a primitive culture that has yet to really explore beyond our own solar system…a culture that thinks that “Iphones” are “really cool”…you seem to think that we even know what to listen for??? Perhaps there’s all kinds of “chatter” going on out there but we haven’t developed the technology to actually hear, let alone understand it.
4.) You assume that just because there isn’t any verifiable evidence (that the general public knows about at least) that this means there MUST not be anyone else out there despite the obvious points I’ve already made. Just because you can’t see the air you breath, does that also mean that it doesn’t really exist as well?
5.) With no facts of evidence to support your claim, you assume that if any microbial life found on Mars (or anywhere else I suspect from your opinion) is “probable contamination from Earth” even though it seems to me that NASA and other organizations have taken pain staking measures to avoid such contamination. Likewise you seem to assume that any such microbial life, even if it is genuine, is somehow insignificant…I won’t even rationalize that sort of idiocy.
6.) With NO facts or evidence to support your claim, but a great deal of evidence that suggests that life “out there” is at least -possible-, you assume that we are “alone”.
Wow dude…you assume A LOT for someone who’s calling others “deluded” aren’t ya? Could it simply be that you’re afraid that just maybe there IS other life out there and that somehow that would make YOU less special in your own pathetic little world? Would life out there somehow devalue your own existence? Are you perhaps afraid of what we could learn both in regards to technology as well as about ourselves simply from the attempt? And how is it exactly that you could be so utterly narrow and close-minded yet call others “deluded”?
Better to have a “sad imagination” than none at all my friend but then as the saying goes, you can’t fill a cup that’s already full…or as my brother says, “You just can’t fix stupid”. Sorry but we’re not the people here who need to get a grip……
i have to admit, i got all excited when i saw the title and thought that a super-earth had been discovered around one of our close stellar neighbors…
tinyurl.com/427k7lo
Really, VIP for Shopper ads in your profile and link, wow. It is truth in marketing at last.
Mary
Interesting article, but confusing lead image as all planets are gas giants.
Regarding the discussion of life, I think the probability that it exists somewhere else is high, but the expected impact of such knowledge may sometimes be overrated. Some day in the future we will find indirect confirmation of extraterrestial microbes via spectral analysis of some atmosphere, it will make the news for some time and then be ignored by the majority of the population.
Now, if we find could find some way to beat light speed first … 🙂