Could Chance for Life on Gliese 581g Actually Be “100%”?


The announcement yesterday of the discovery of the closest Earth-sized planet found so far that also exists in the habitable zone around its star is certainly exciting (read our previous article for all the details). Gliese 581g is surely a potential habitable planet where liquid water could exist on the planet‘s surface, and many are touting the old adage of where there’s water, there’s life. However, some quotes from one of the scientists involved in the discovery might be feeding some wild speculation about the potential for life on this extrasolar planet and elsewhere. “Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent,” said discoverer and astronomer Steven Vogt during a press briefing yesterday. “I have almost no doubt about it.”

Yes, that is an exact quote. He really used those words. He also said that it would be pretty hard to imagine that water wouldn’t exist on the planet, given the ubiquity of water in our solar system and beyond, and the habitable region in which this planet orbits.

Also participating in the briefing was Paul Butler of the Carnegie Institution of Washington, which provided funds for the observations at the Keck I telescope, and his comments were more tempered.

“Any discussion of life on at this point is purely speculative,” Butler said. “What we know is that this planet exists at the right distance for liquid water it has the right amount of mass to hold on to its atmosphere and any liquid water on the surface. So any subsequent discussion of life there is purely speculative. That being said, on the Earth anywhere you find liquid water you find life in overwhelming abundance. The question should be, if this planet has liquid water, how can you rule out life doesn’t exist? It is pretty probable that anywhere you find liquid water pooling, that you would find life existing.”

Are Vogt’s claims too extreme, or were they made in exhilaration during an exciting announcement? This has been a topic of debate on Twitter this morning. Some wondered if Vogt had been misquoted, and many expressed that Vogt’s words may fuel off-the-deep-end speculation about the certainty of life on another world.

“Until we know more about this planet and the origin of life itself, any claim of certain habitation is idiotic and does not serve science,” said Dr. Stuart Clark (@DrStuClark), author and astronomy journalist. To clarify, he wanted others to know that he thinks just the claim is idiotic, not the discovery or the people involved.

“As cool as it is, please realize that right now all we really know about it is its orbit and estimated mass. That’s it.” said Lee Billings (@leebillings), editor at Seed Magazine. “In other words, barring observational evidence that may still be a generation away, Gliese 581g is ‘Earth-like’ only in terms of mass/orbit.”

From our pal Phil Plait, the Bad Astronomer (@badastronomer): “I understand what he meant – he thinks it could have life – but it was phrased unfortunately, and the media have jumped on it, of course.”

From David Masten (@dmasten), CEO of the commercial space company Masten Space Systems: “I have an opinion or 3 about life on anything in Gliese 581! And I’d dare say much closer to zero chance. But I’m not an astrobiologist.”

“Claiming a 100% chance of life on Gliese 581g is definitely an overreach,” said astrophysicist Juan Cabanela (@Juan_Kinda_Guy) at Minnesota State University Moorhead, “given we currently have a sample of 1 planet with life.”

“Vogt’s extrapolation was certainly quite a leap. On the other hand, the media might finally get it that some scientists really do think life everywhere is possible – but not bug-eyed aliens” said Robert Cumming, (@maltesk), journalist at the Swedish magazine “Populär Astronomi.“. “Then we can also discuss why there might not be life everywhere after all.”

Mark Thompson (@PeoplesAstro), Astronomy presenter on BBC’s the One Show said the Vogt’s quote was “absolutely and totally inappropriate. We can’t even be 100% sure it’s made of rock!!!”

From astronomer, educator and journalist Nicole Gugliucci (@noisyastronomer): “The public seems to have enough trouble trusting science these days without scientists making bold statements like that.”

“100% is ridiculous,” Tweeted frequent image contributor to Universe Today, Stu Atkinson (@mars_stu). “No possible way anyone could know that, surely?”

Many expressed excitement over the discovery, and Stu articulated perhaps the most colorful, which was re-tweeted several times yesterday: “Ah, a PROPER planet!” Not a great fat bloated sweaty “Who ate all the pies” ‘hot Jupiter’ tearing insanely around its star.”

What are your views?

*all Tweets used by permission.

Here’s an article about abiogenesis, theories about how life got started here on Earth.

63 Replies to “Could Chance for Life on Gliese 581g Actually Be “100%”?”

  1. People confuse “habitable” with “inhabitated” and with “habitable by humans”.

    So to clarify.
    “Habitable” means it doesn’t have show-stoppers for life, and in a more narrow sense, doesn’t have show-stoppers for life-as-we-know-it, meaning anything vaguely similar to what we see on Earth. This is generally taken as “can support liquid water on the surface”, while acknowledging that yes, there could be other types of chemistries and life that are not water-based. To me, higher magnetic fields than we’re used to, for example, do not make a planet non-habitable.

    “Inhabited” means that life developed there.

    “habitable by humans” means that you survive on the surface with reasonable means of protection.

    The “100%” quote was about habitability, the first criteria, not the other two. Nobody knows if there is life there. Nobody knows if the conditions are good enough for people to survive on it. What they said is that they know for sure it is a rocky planet with the right temperature range, which means there’s water on the surface. The tidally locked situation just makes it different than Earth, but in no way uninhabitable.

  2. Perhaps we should remember, during our speculations about the existence of life on planets in the “habitable zone” (i.e. liquid water can exist on the planet), that liquid water may be a necessary condition for the existence of carbon based life like us, but it is not a sufficient condition!

  3. I think you can rephrase it to “Earth bacterial life could survive on that planet if we drop a bucket in a puddle out there.”

    It does not mean that life actually started out there.

  4. Eh well, his hypothesis is that there is a 100% chance of life. I fully endorse investigation! When will we get spectra of the atmosphere? I’m surprised that hasn’t been done already..

  5. Those with Twitter I highly recommend tweeting this article all over the place to combat the over-the-deep-end reactions.

  6. Do we have the technology to send a spacecraft 40 LY and still function autonomously to enter Gliesian orbit and beam images back to earth? Will we ever consider such a mission to a super-promissing spectrally-suggestive-of-life planet? Would you support such a mission even if you would not see the results in your lifetime? I think I would.

  7. Ted Judah, all we need to do is create a worm hole here, ship one of the openings to that planet and we have instant access just like a Stargate. If we can reach 0.5 times the speed of light with that ship.then the portal can be open in 40 years from now. 🙂

    I am just wondering, can we ship a second bigger wormhole through a wormhole?

  8. No *&@^ing way is it 100%. There are a number of things which have to be overcome. The atmosphere can’t be a hothouse CO_2 atmosphere. This planet could easily be a 300C autoclave envirnoment with maybe 100 torr of pressure. If the atmosphere started out with too littlepressure it could have been lost by now.

    This is intriguing however, and there is a chance for life here. If this could be imaged and found to be a double planet with a quick orbital rotation in a tidal lock I would feel even much better. Much more data is needed, including on the chemistry of the atmosphere and if possible a measurement of its blackbody radiation temperature.

    It is also worth noting Vogt said, “Chances are 100%,” not that there is a 100% chance for life. I think this amounts to saying one can impose a Bayesian prior estimate to this problem of whether life exists there. The problem is that it is still tough, for we don’t know what the distriubution of possible planets is.


  9. Why would it take “another generation” to get more in-depth observations of this planet? Surely we can a spectra of the atmosphere? There must be more we can do too.

    As for the comments from some of these scientists, it seems they haven’t been reading Universetoday! What are their thoughts on the dead world scenario? Or a Venusian hurricane planet? Or the weak magnetosphere scenario where water and/or lighter atmospheric elements are gone?

  10. As an actual astrophysicist I’m going to leave the speculation as to whether this planet is habitable to people who model atmospheres and stuff.

    What I AM going to comment on is our ability to obtain observations which can clinch the argument one way or another. IT DOES NOT REPEAT NOT EXIST AT THIS TIME. It took 11 years of measurement with a hi-res spectrograph on one of Earth greatest telescopes to even tease out the radial velocity signal. 1.6 m/s is a value I have never heard of before, it’s incredible. Even confirming the existence of this planet has pushed modern techology to the limit.
    Remember the definition of a parsec? At one parsec distance (about 3 ly) one AU subtends one arcsecond in the sky. Gliese 581g is six times further away and less than half as far from its star. That’s a separation of under 0″.1 for a very small body of uncertain albedo. NOTHING exists that can separate this from the star and actually take a spectrum.

    Face it. Before JWST and the upcoming 30m class of ground-based telescopes, nothing more will found out about this planet. But for sure the system will be a prime target then.

  11. I think that the term “habitable zone” is a misnomer because we have evidence from our solar system that there are 3 planets in this zone, but only one which supports life. As people have mentioned, there are many things that could prevent life from forming – no atmosphere, no water, too much atmosphere, poison in the atmosphere, too hot, too cold, etc… Seems like a huge stretch to say that just because a planet is located in the habitable zone means that it harbours life. Not to mention the fact that each planet system we find destroys all of our models for planetary formation and this planet may be in a form that we haven’t even considered yet.

  12. There is another things which needs to be considered. These planets are rather heavy and in close orbits. Take a look at

    and these bodies are close to each other and gravitaitonally perturb each other. It seems as if these would gravitationally perturb each other in ways that could be quite dramatic. It is possible they rattle each other enough so they might drift in and out of the so called habitable zone.


  13. Considering that Gliese 581g lies within the habitable zone and by the tidal lock in a convective atmosphere will have liquid water conditions somewhere on its surface, it is nearly 100 % certainty it is habitable. A convective atmosphere will naturally give a livable annulus, the circulatory systems will be much more stable than here.

    As we know from Venus a (near) locked planet retain atmosphere. The remaining water content will depend on the starting water content. The two showstoppers of abiogenesis inhibitor is a non-water world (originally or by the hydrogen loss from locking), or a water world (with scant nutrients at livable pressures).

    But as we move towards the ice line outwards the habitable zone of M stars we will touch a narrower “goldi-lock” [sic] zone. Gliese is AFAIU luckily situated to be an Earth analog in that respect, not a Venus analog.

    So much for A on habitability, which is context dependent but its major parameters is temperature (~ 20-40 Celsius optimum for cellular metabolism) and water (~ 100 % RH optimum for cellular metabolism).

    As for the Q of inhabited, we can see from the speed with which life established on Earth, it is an exceedingly easy process. The long life of M worlds in general, and of Gliese 581 especially (7-11 Gy compared with our own 4.5 Gy), makes such considerations nearly moot.

    The problem likely is not to have life, the problem is _not_ to have life under those circumstances.

    [Btw, as I noted in the previous post, the restricted habitable volume in the annulus of a tidal locked M world will be offset by the larger frequency of them. Expect to have the main biosphere volume on such worlds!]

  14. these bodies are close to each other and gravitaitonally perturb each other.

    In general planets are found closed packed with respect to disturbances. I believe the orbit circularity of the new planetary fits, as good as our system AFAIU my quick browsing of the paper (it’s on arxiv), rejects that the system is in a disturbed phase.

  15. Oops! “The problem likely is not to have life, the problem is _not_ to have life under those circumstances.” – The problem likely is not to have life, the problem is _to not_ have life under those circumstances.

  16. Also, re disturbances, I just remembered that the paper has a discussion on how the keplerian tree fit procedure easily exaggerate eccentricities when data is missing.

    If so, I would not trust orbital predictions until all or nearly all planets are found, which today seem to take 11 (!) years – or more.

  17. I don’t see the big problem- since we do know only it’s mass and orbit, why not guess that there’s life? It’s just as good as the opposite guess. A percentage chance is not the most meaningful statement, what’s wrong with 100%?

    Vogt knows that there’s a habitable zone climate and probably water, and water means extremophiles at the very least (in many people’s opinions). Really I don’t mind his statement, and besides I like optimism…

    He also said “my own personal feeling…” He didn’t say “After months of exhaustive calculation…”

    Lighten up! Go Gliese581g! xD

  18. Torbjorn,

    I had not considered the long life span of these systems. 7 – 11 Billion years would give ample time for life to arise, even if large areas of the planet are unsuitable.

    I imagine there must be a probability calculation that could be derived from all this.

    Factors perhaps being:

    1. Time since planet formation
    2. Stability of star
    3. Stability or orbit
    4. Size of planet
    5. Likelihood and frequency of impact events / time
    6. Volume of planet conducive to carbon-based life as a factor of time.i.e. lower value for areas further away from the twilight zone, mapped over geological time (crust cooling etc.)
    7. Water volume / time
    8. Other atmospheric factors.
    8. Geological changes (tectonics? Crust melting events?)

    Do we have enough data where we could figure out some rough probability estimates? Please forgive me if some of my language here is incorrect as I am not a mathematician!

    Gieven factoring in areas of the planet that would not be suitable for life. of life much higher, even if the voume of space on such planets suitable for life is less thashould giveyears does give a good timesp

  19. That is the issue with orbits. Over a long time period of many millions of years there could be significant drift in these orbits. So a planet in the habitable zone might in 50 million years drift out of it.


  20. Well, the phrase he used is very vague – he didn’t say ‘I believe that the probability that life exists on this planet is 100%’ , just that ‘the chances for life on this planet are 100%’. This could mean that he thinks the chances for life surviving somewhere on this planet are 100% if indeed they are there… etc.

    Still, it is a reckless (and in my view, completely incorrect no matter how he meant it) comment. I can just imagine all the bong-smoking hippies and cult leaders working this new ‘discovery’ into their cosmic fairytales as we speak.

    It detracts from what is an otherwise brilliant effort by the team. An amazing result, and certainly this would seem to up the confidence levels that such planets are relatively common…

  21. @OLAF: Actually, we don’t know it’s tidally locked from measurements.

    This is just a very good guess, following what we do know from, e.g., moons in our solar system (including our own). After such a long time (7 – 11 Gyr was mentioned) and so close to the star, tidal locking is almost assured.

  22. While we may all fervently wish for other inhabited planets and rightly hail the stupendous advances in technology thank goodness for the sane voice of an actual astrophysicist [Don A.]. As he says it’s taken 11 years to find this tiny twitch in the data so any further assumptions are far too premature. Speculation around the fire with a glass of brandy are ok but let’s not get carried away.

  23. I have one major problem with Vogts statement if a 100 percent chance..

    Stellar flares!! I am surprised no one has pointed out yet here and other forums that on Red Dwarf stars it is thought that most would have gamma and xray flares more violent than our sun… Considering this planet is at 0.15au, the chance if any life being sterilized is high..

    To me 100 percent seem waaay over optimistic and I am an optimist… Unless I hear that these scientists can quantify Gliese dwarves xray flares I will continue to feel this scientist made an irrational statement…

  24. “Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent..”

    bwahahaha! can i please have more funding?

    but seriously, you guys know that crowell’s prediction is the most likely one, right? the chances of it actually being anything other than a deathtrap are extremely small.

    what should be taken from the discovery is confidence for finding more of them (and perhaps much better suited) in the future.

  25. The likeliness to discover earth-sized planets orbiting close Red Dwarfs has grown during the last years. So we could expect to find a planet like Gliese 581g orbiting a Red Dwarf like Gliese 581. In the years to come we will find a lot more systems of this kind. So keep cool and look forward.
    Looking forward for what? Gliese 581 is some 20 lightyears away. This is some 200 trillion kilometers. Travelling such a distance at 40000 km/h will take more than 570000 years, one way! So, there is no real option to go to, or ever reach that planet.

    It is a strange place for sure, and strange places arouse our curiosity. But this doesn´t make Gliese 581g a beautiful place, even if we dream it to be one. Liquid water is not necessarily fresh and pure, atmospheres do not necessarily contain oxygen, and if lifeforms exist there, they might be ugly and nasty in our eyes and skin. A new world is no second paradise created for us, it was not created to meet our dreams and our standards, it simply is what it is, on its own right. There are billions of such worlds out there …

    In a few years we might be able to obtain spectra of that planet´s atmosphere, and of the atmospheres of further planets in other systems as well. Comparing these with the atmospheres of planets of our solar system, we may find out whether the atmospheres found in our system are alike to those in other systems, or not. That will be the real discovery we get from our discovery of other planets.

  26. Weasel,
    don’t forget that you have a huge planet between life and the star that can shield life. In this case tidal locking could be useful.

  27. We may not know enough about tidal locking, or the weather on such planets, or stuff like that. But what are the chances of some science fiction book or blockbuster film about a small bunch of freedom-fighters being cast out of the habitable belt and making a perilous trek acoss the hot/cold side to strike a blow for freedom, etcetera?

    About 100%, I’d say…

  28. Saying that there is a 100 percent chance for life there is proposterous. This planet could have evolved along the same track as venus. It may not have plate tectonics. It could be a water world with no land mass above sea level. It may look like Europa and be totally encased in ice. If this planet were transitiing in front of its star we could at least sample its atmosphere and that would give us a big clue, but as I gathered it isn’t detectable using the transit method. If there is liquid water on its surface then the chances of there being simple life forms is pretty high in my opinion, but that is a subject of much debate. Eventually we will be able to sample the oceans of Europa, Enceladus, and Ganymede. In addition we will be have had a good look at the Mars subsurface. If we find simple life there then it argues strongly that we will find it on this planet, given the right conditions. If not, then the opposite argument is more likely true. As it stands now, I would say that most likely there will not be life on this planet given what little we know so far.

  29. Would life have to be extremophiles? Maybe, and remember that the process of converting photons into bio-energy might be different since the light spectrum is different.

    GBendt: If we send a probe to this star it will obviously be faster than current space craft. I discuss this in the affiliated blog article at UT ”
    2010New Earth-sized Exoplanet is in Star’s Habitable Zone,” based on my book titled “Can Star Systems be Explored? The Physics of Starprobes.”

    weeasle: Good call on flaring. Yes a lot of M-class stars do flare up. NOt all of them do though, and I would suspect that if this star flared up a lot it would have been cited by now. I will see if I can look that up. Moderate flaring might not be too bad if the atmosphere is thick enough to block the gamma and UV from the surface. Then again if it is thick enough it might be IR trapping. Also even if the star does not a flare up now that does not guarantee it has not done so in the past or will do so in the future.

    Greg: as Don Alexander pointed out this will require far greater resolution. The JWST will undoubtedly be put to this task. So we have to wait to get further data here.


  30. Looking at Torbjorn’s post, my layman optimistic guess is above 50% for all planets found in the middle of habitable zone, but for this specific one chances are 25%. It would be funny if actually planet C or D had a life. I think there is a good chance that one of them will have a life at some point. :d

  31. To Brobof and Olaf.

    Thank you Brobof for the link to the fine research paper.

    I am no atmospheric physicist but I can tell you the likelyhood is higher that the dayside would be totally sterilised by the likely cyclical violent x/gamma ray flares from Gliese Dwarf.

    The nightside could theoretically support life in pools of water if this life could adapt without photosynthesis as indeed some crustaceans (krill and other exotherms and extremophilic bacterium) and other lifeforms around geothermal vents do on earth.

    However, all these are assumptions based on the presumptions of genisis of life on earth, of which we understand little, especially early earth evolution and origins.

    I think it is irresponsible to extrapolate 100% chance when we know so little about how life takes hold – Panspermia, Transpermia, One-off accident? Its anybodies guess until we get powerful scopes, detectors and hadron colliders up to full juice + the public enthusiasm and political will. Most people are more focused on the day to day but soon hopefully we will get to know some pretty profound answers.

    Thanks – weeasle

  32. ps. Thanks LC 🙂 Please PM me (or next time you see me reply) I would love to hear any info you can dig up on Gliese stars X-Ray flares… Cycle, Strength, etc.

    Exciting times! Cheers – weeasle

  33. Humans’ inherent resistance to the idea of other life in the universe is probably as subversive as “scientists” of the 1500’s lighting up their campfires to “educate” everyone that didn’t want to believe the Earth was at the center of the solar system.

    I understand the overall debate about “100%”, but the overreaction to that quote is a little preposterous. I bet if the guy said there is a 100% chance that there ISN’T life, it wouldn’t be getting nearly the reaction.

    JIm Krug

  34. Regarding the stability, and flare activity of Gliese 581, a quick check of Wikipedia reports that MOST satellite observations find a peak-to-peak variability over 6 weeks < 5 mma with no coherent variations in phase with 12.9-d period and the RV signal not due to rotational modulation due to spots or granulation patches. Also Gliese 581 appears to be too massive to be a flare star which makes life more probable. However Gliese 581 does emit X-rays.

  35. I also think that a big sea also protects from solar flares big time.

    I have been wondering how a spacecraft would get to Glies 581. Could it has a near straight path or Will it get influenced by other stars that are nearby.

  36. Looks like my guess was illogical. :d I’m giving to this planet above 50% chance to have a life.

  37. On the Sky & Telescope blog

    there is the comment

    A tidally locked world, it turns out, would need an atmosphere only about 1% as thick as Earth’s to distribute enough heat from the dayside to the nightside so that the atmosphere would not freeze out as a solid crust on the nightside.

    So a maritian atmsphere density appears sufficient to keep the atmosphere from freezing out.

    I have not found out anything about flaring.


  38. Once I read a very old SF book. It was about people travelling to a far Star just like Glies 581. It took almost a lifetime. Only to discover that when they land on the planet that it was already civilized big cities by humans.

    What happened is that space travel got better during their journey and actually passed them while they were flying a snail speed.

  39. Thank you Olaf, LC, Scepticim, and all of you for your comments.

    I still personally believe the chance of life would be higher on one of the moons around one of the larger gaseous planets in this system.

    Our moon helps extend our Van Allen belts to provide gamma and x-ray irradiation shielding. I feel this is a strong prerequisite and possible indicator of a stellar environment conducive to abiogenisis.

    I also believe photosynthetic atmospheric microbes on earth play an important and not fully understood role in converting earths atmospheric oxygen and other volatiles and increasing the nitrogen content of our atmosphere (upwards of 90% by volume).

    These factors may be necessary pre-requisites to a conducive environment for life is my main point. I think there definitely is a lower bound that could be agreeable for the threshold of habitability – but I would place it around 50% at this time without further data on the X-Ray flares 581g would be subject to.

    Thanks -weeasle

  40. We could send a signal to the aliens and within 20 a worm hole could open up here on Earth because we called.

    I have no doubt that there is life everywhere, but that does not mean that it is intelligent like us. Probably microbial. .

  41. To be honest I really would be thrilled if the JWST finds that this planet has an oxygen atmosphere, with maybe traces of methane. Sending a robotic probe there would be a “must do” program. We just simply must get a close up look at what is happening there!

    However, we can fool ourselves. In fact Feynman said the easiest person to fool is one’s self. That is something best avoided.

    Wormholes? They are not likely. If the topic comes up I will reiterate the problem with these. They run into terrible problems with quantum field theory.


  42. I go away for a few days (yes under a rock) and I miss this, thought this was a prank or something at first. A near Earth sized planet in the H zone, amazing, we would need more data to make any further assumptions though. I agree with LC’s post above, interstellar probes, the way to go.

    Isn’t this great. 🙂

  43. LC, I think OLAF meant his wormhole remarks as a joke. We discussed the whole near impossibility of manipulating negative energy (are we even sure this exist yet?) at the macro level many times.

    In the meantime, we need to get Hal up and running. Is there any realistic chance a hobbled version could suffice? Surely we could produce a primitive semi-autonomous computer system right now. Yet how do we insure the 100 year survival of such a complex system?

    This is starting to sound like fantasy…

  44. We don’t even know if water is needed for life. With only one example of life in existance, we cannot be sure what life requires. We may not even recognize alien life when we see it, because, well, it would be alien.

    To say anthing with 100% certitude (except that the planet was there some twenty years ago) is irresponsible.

  45. weeasle: a bit of further information that might be useful re Gleise 581.

    Note: Behind paywall! Also note the comment “the Sun as a star fits well into the derived relations”

    Statistics of BY Draconis variables

    Author: Alekseev, I.

    Source: Astronomy Reports, Volume 44, Number 10, October 2000 , pp. 696-700(5)

    Publisher: MAIK Nauka/Interperiodica

    A statistical survey of 113 spotted red dwarf stars that are known or suspected BY Draconis variables is presented. Typical indicators of stellar photometric activity—the amplitudes of the rotational modulation and seasonal mean brightness variations ?V and ??V?—are compared to the global parameters of the stars. First, photometric variability shows a weak dependence on spectral type; second, ?V and ??V? grow with increasing stellar rotational velocity and decreasing Rossby number, with the dependences saturating at the critical values V crit?15–20 km/s and Rocrit?0.2–0.3; and third, the Sun as a star fits well into the derived relations. Thus, the spottedness of stars, like other indicators of stellar activity, depends on their global parameters.

    Further information about BY Draconis stars:


    BY Draconis star

    A type of rotating variable dwarf star, of spectral type G, K or M, that shows quasiperiodic light changes, ranging from a few hundredths to 0.5 magnitude, with a period from a few hours up to 120 days. The variations are due to surface features, such as starspots, passing in and out of view, as the star spins on its axis. Some of these stars also show flares, similar to UV Ceti stars, in which case they belong to both types of variable star.

    BY Draconis itself is a close binary consisting of a K6V dwarf and a M0V dwarf with an orbital period of 5.9 days and a mean separation of 0.05 AU. The M star exhibits flares that increase its luminosity periodically by a factor of 2 to 4, and also shows smaller variability keyed to its orbit and chromospheric activity.

    A nearby example of a BY Draconis star is Gliese 581.

  46. I think we are taking a great leap to consider it possible for life with it being tidally locked. First of all, think of a seed and what it takes for one to sprout and grow. It requires just the right amount of nutrients. Then, the right temperature. Then it takes water and sunlight. If any of these variables are out-of-whack in any way, the seed does not sprout and probably dies. So, then, we apply these conditions to life on other planets. Considering it is a tidal lock, I don’t think we have much of a chance at all. Our planet rotates at a specific angle that gives us the 4 seasons and causes our atomsphere to churn and create rain and clouds and gives us the water cycle. It also causes our oceans to develop a current which reacts with the lower atmosphere to mediate the climates. I just don’t see how a tidal locked planet can do all of that and keep harsh differential climates from developing with no seasonal changes.

  47. …I didn’t even go into the 30 day cycle and the greater possibility of asteroid or meteor collision if it doesn’t have any natural satellites. We’ve got a long way to go to get to the point of saying it might have life.

  48. Yes the wormhole was a joke.
    But I wanted to make a point that maybe any aliens there could come and visit us once they discover that we sent them a signal. Who know maybe they already sent a spacecraft towards us since they received the first TV signal.

    What I am now expecting are some quack nuts that are now going to pretend that Gliese aliens are contacting them via channelling. I expect new sects popping up and starting to worship the aliens that are super intelligent since thy get as old as 1000 Gliese 581 years average. Compare that with our mere 100 Earth years intelligence!

  49. SkepticTim: This variable nature does not seem to principally involve flaring. Of course it is hard to say what influence this might have on any planetary evnironment.

    Olaf, I sort of figured the wormhole comment was at most half serious. When it comes to time on these planets, it is curious to note that these stars last a very long time. If the orbit of this planet is stable over very long time frames, then if it is life bearing it might remain biologically active for 10s of billions of years.


  50. 57 comments and counting. The other post of Glieses has 47. Very popular topic we got here. Maybe the exoplanet search is the one field Astronomy that can really capture the public’s imagination.

  51. Exoplanets are fun. This is even more the case if there is a chance for life on a planet. There is a bit of a journalistic funny business going on. The previous UT article has a nice picture of an Earth-like planet, complete with blue oceans etc. The oceans would not appear that way, since there is little blue light from this star. If you stood on the surface at daylight the sky would be black, so there would be much less diffuse scatter of light that we see on Earth. Lighting would appear similar to being under sodium lights at a stadium during a night football game. Since the habitable zone n the planet would be on a longitudinal annulus where the star light is nearly tangent to the surface, shadows would be long, giving the environment potentially a rather Halloween appearance.


  52. “What I am now expecting are some quack nuts that are now going to pretend that Gliese aliens are contacting them via channelling.”

    Lasers, actually: (including the linked interview)

    Note: In defense of Dr Bhathal, I think he makes clear in the interview that he doesn’t buy into the UFO-ET nonsense the reporter espouses and appears to be a legitimate researcher pursuing optical SETI. Of course that’s not going to get in the way of the ET spin of the article (I can’t even find where Dr Bhathal mentions a possible ‘signal’ from Gliese 581 OR the attribution of the ‘signal’ to G 581e).

    From the interview:

    “Unlike most of the tin-foil hat wearing whackadoos in his field[optical SETI??], Dr. Bhathal is a hard scientist working with university money to find extraterrestrials. In fact, he teaches the only Search for ExtraTerrestrial Life class offered in all of Australia. His hard-nosed approach perhaps explains why you’ve yet to hear this big news: Before he can broadcast his findings to the world, Bhathal must put them through rigorous examination”

    Of course, in the article ETs from Gliese 581 is almost a forgone conclusion. Time to ring the (fictitious) UN alien ambassador. 😀

  53. I just want to add something.
    “Gliese” stars are the top 1000 closest stars to our sun.

    Also Gliese 581 = GJ581 = HIP74995 = many other alias names.

  54. I honestly can say I haven’t read all the comments here but has anyone been thinking about how much longer these planets have been around than for example our own solar system. I think the figures on the age of this system are on the order of 7 billion years minimum. That would give plus 2 billion years evolution advantage on us, so these possible lifeforms may have visited us already albeit before most lifeforms evolved on Earth. Just some hypothetical food for thought.

  55. 1 light year is long even, voyager1 and 2are not out of our solar system yet and they traveling now for 30+ Gliese 581is 20.5 lights years away and it would take

    At a space shuttle’s top speed 17,500 MPH it would take 766,000 years to get there

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