Theoretically, Alpha Centauri should have planets

By Phil Plait | March 7, 2008 2:13 pm

A new paper just published by a team of planet-hunters shows that theoretically speaking, not only can Alpha Centauri have planets, it should have them.

A bit of background: Alpha Cen is actually a binary star, with one star much like the Sun (called Alpha Cen A) and the other a bit cooler (Alpha Cen B). A third star, Proxima Centauri, orbits very far out from the central binary.

Alpha Cen is the closest star system to the Sun that we know of, at a distance of 4.3 light years, or roughly 40 trillion km (24 trillion miles). Since it’s close, it’s one of the most common stars used in science fiction.

Planet formation around one star in a binary can be tricky; the disk from which the planets form can be disrupted by the presence of another star. However, a team of astronomers including Javiera Guedes and Greg Laughlin used computer simulations to see how planets could form in the Alpha Cen system specifically. They did what’s called a Monte Carlo test, running the simulation over and over again with slightly different input parameters every time (like, disk density, composition, and so on).

Remarkably, what they found is that they got a terrestrial (rocky) planet about the size of Earth orbiting Alpha Cen B every single time, and in many cases was at the right distance from the star to have liquid water.

Holy Haleakala.

A planet like that would be difficult to detect if it exists, but not impossible. In fact, not only do we have the tech right now to do it, but paper co-author Debra Fischer is looking for such a planet. It’s possible that we may find such a planet in just a few more years.

It’s difficult to say what that would do for awareness of astronomy; I can’t help but think it would make a huge splash. First, to find a planet orbiting the nearest star, and second, an Earth-like planet… wow. Still, since the result is still only theoretical, it’s too early to get too excited about this.

Well, maybe just a little excited. :) It’s hard not to be. But we’ll see soon enough.

CATEGORIZED UNDER: Astronomy, Cool stuff, Science

Comments (84)

  1. firemancarl

    Can Hubble or Spitzer et. al. look that far away and get a good view or does the light from those two stars make seeing the planet all but impossible? What color shall we think the inhabitants would be? My vote goes to a planet loaded with hott sexy green babes. Ya know, like the ones Kirk gets to party with.

  2. Chip

    I hope so. 4 light years away is a astoundingly difficult distance to eventually reach with a self servicing, rapidly traveling robotic probe taking years to get there, but not completely impossible – some day.

    However if we discovered an Earth-like planet 200 light years away – that would be very exciting too, but I’m not sure we could ever go there, though we might find out more by observing long distance, with extremely sophisticated space telescopes.

  3. tacitus

    Given enough time, our improving technology will let us know for sure what’s up with our nearest neighbor — I’m guess definitely within a decade.

    And it definitely would make a huge splash, especially if it’s turns out to be a planet we could potentially live on (even if it was just slightly less marginal than Mars).

    It would spark renewed (and probably continued) interest the possibility of getting there. Yeah, that is a long, long way off, but being able to dream is an important first step in the process, and anything that fires up the imagination will be welcome.

    Shorter term, such a discovery would lend a great impetus to building telescopes capable of imaging the planet(s) directly so that we can tell what sort of an atmosphere it has, and even if might support life of some kind.

    All in all, it would be an amazingly beneficial discovery for astronomy as a whole.

  4. tacitus

    My vote goes to a planet loaded with hott sexy green babes. Ya know, like the ones Kirk gets to party with.

    I’m just hoping we get there in time to find out about the Vogons’ plans to demolish Earth in order to make way for the hyperspace by-pass they are going to build.

  5. tacitus

    However if we discovered an Earth-like planet 200 light years away – that would be very exciting too, but I’m not sure we could ever go there, though we might find out more by observing long distance, with extremely sophisticated space telescopes.

    “Ever” is a very, very, very long time… :)

  6. Steuard

    What an intriguing result! Do they have any idea of what sort of mechanism would give rise to this so consistently? How frequent is terrestrial planet formation in simulations of more common stellar systems?

    As a side note, I’d be happier if you linked to the abstract page on arXiv rather than directly to the PDF? I usually like to read the abstract before deciding whether to download the whole article.

  7. Nerrin

    Sid Meier was right!

  8. james000777

    Even if there is a planet, and even if it is rocky, and even if there is water, and even if we do find it, there is no way complex life could exist in a binary star system. Too unstable.

    Monte Carlo simulations are susceptible to what I call the Gi=Go phenomenon. Garbage in = Garbage out. I have no clue – have not read the paper so I really should not comment…but is is interesting that a planet should be there…

  9. Gadren

    Let’s hope there aren’t mindworms.

    Seriously, though — this is wonderful. I really hope it turns out to be the case that Alpha Centauri has planets. If we get actual observations demonstrating the presence of a planet, such a concrete goal could really energize the space movement.

  10. Dennis

    I discussed this with a friend who is a Native Canadian. He said if there is a planet like earth there he would like to send a message before we visit. You can imagine what the message was.

  11. nfk

    Supposing we do detect an Earth-like planet orbitting the stars in the next few years, what is our best technology to get a probe to travel the 4 light years?

    Lots and lots of assisted velocity boosts? An ion engine? A laser assisted solar sail? How fast could a probe get there?

    And then a 4 year lag in communication would drive me crazy!

    Me: “Did the probe make it?”

    NASA: “Come back in 4 years buddy.”

  12. Gadren

    Here’s an interesting question: what would the colonists look like to Earth on their voyage? That is, if the people in the spaceship going to Alpha Centauri continuously sent a “live” (to them) video directly back to Earth using radio waves or something similar, what would it appear like to us? Would the video get slower and slower as the colonists got further away? Because when they get to the distance of the Moon, it’s a delay of a second, but four years when they get to Centauri… but at each location, it’s not like the image is “updating” less frequently…

  13. Andrew

    The main problem with interstellar travel is fuel. Even with an anti-matter drive (which we can’t build), we could not get faster than .1 C. 4 light years away, at .1C takes 40 years.

    An Ion ship is not possible to do anything similar.

    A light-sail ship assisted by a laser could do better, as it would not have the same fuel problem. Still, to get there in less than 40 years it would require lasers as far beyond our current capacity as the theoretical anti-matter drive star ship is beyond our current anti-matter production capacity.

    That is: No, we can’t get there with existing technology in less time than 200 years. But in 100 years, I would expect to be able to get there in less than another 100.

    I.E. It is smarter to wait to build it.

  14. tacitus

    Lots and lots of assisted velocity boosts? An ion engine? A laser assisted solar sail? How fast could a probe get there?

    Well, I believe that the fastest conceivable speed with presently conceivable technology is about 10% of the speed of light, and even at that rate it’ll take a least 50 years to get there once you factor in the acceleration and deceleration, so I doubt any of us alive today will get to see the completion of such a mission :)

    And I really don’t see us even trying until we can get the mission time down to below the lifetime of those involved. So missions at, say, 2% of the speed of light (taking 200+ years to get there) just won’t be attempted (perhaps unless we knew for sure there was life there).

    Until we have the means of getting there in a reasonable amount of time (if we ever do) then missions like ever-larger, ever more capable space telescopes will always be a more productive use of time and resources. There is no theoretical reason why, some day within the next century, we can’t have a gallery of images of extra-solar planets that rivals images of our outer planets as seen from Earth today. Sure it’s a tall order, but if physical interstellar exploration is out of the question, then building mega-scopes in space, or on the Moon, or on an asteroid, is by far the next best thing to it.

  15. martin

    i welcome our new xenofungi overlords.

  16. Alan

    james000777 wrote: “Even if there is a planet, and even if it is rocky, and even if there is water, and even if we do find it, there is no way complex life could exist in a binary star system. Too unstable.”

    Is it really all that unstable? The two larger stars in the system orbit each other at a distance of 11 to 36 AU, and the third star is 13000AU out. I don’t know enough about celestial mechanics to tell whether that’s any more unsettling than having a Jupiter and Saturn in a single-star system.

    I’m amazed that there can be any life at all here on Earth in water above 200F, or 3 miles underground, so I expect that the universe has some more surprises when it comes to where life (both simple and complex) can be found. Of course there’s the really remote chance that somebody else found Alpha Centauri interesting and moved there after growing up in a more stable place. :)

  17. Greg in Austin

    Message in a bottle. Using the recently touted “Beaming the Beatles to Polaris” technology, we should send a message to the Alpha Centauri system, asking if anybody is home. In 8.6+ years or so, we may get a response.

    And hopefully, the Alpha Centaurians (or whatever they call themselves) will be both benevolent AND have a greater level of technology to get here faster than we could get there. Then that could totally happen in our lifetime.

    The next trick is actually writing the message, and working out those pesky details of how to send it. ;)

    p.s. And if they’re the evil galactic overlord kind of civilization, and come here to destroy us all… well, we were bound to do that to ourselves sooner or later anyway!

  18. Doesn’t anyone on here remember we sent a craft to Alpha Centauri a while ago? And it was lost?

    Sheesh… you would think a whole family on a mission to the nearest star system, and then being lost in space, would evoke some kind of remembrance.

    You people… so narrow-minded… so unemotional… so forgetful.

  19. Garden — The “delay” in communication you speak of is in how long, once the message is sent, it takes to reach us. The “live video” would arrive at normal speed, just 4 years after-the-fact.

    The video only slows down if they are moving away from us very quickly. (And by “very quickly” I mean in relation to the speed of light, not “10,000 Km/h is very quick”.)

  20. Greg in Austin:

    Sure, they got lost. But, since we know that they’re alive and enjoying many adventures, I don’t think we need any “remembrance”.

    (On the other hand, they _need_ to stop off at lots of planets, since there are no bathrooms on the ship.)

  21. asknot

    An earth-like planet around another star. . . . and not just any star, but the closest star? Yikes. If this turns out to be real, what would that do to current estimates on the frequency of earth-like planets in the galaxy?

    So much for the “rare earth” hypotheses.

  22. Gadren

    Ken B, I understand that the video of them at AC would take 4 years to get here, and 2 years to get here from a point halfway there, etc.

    But would it still hold if we had a continuous “live” feed, not just packets of video sent at regular intervals from the ship?

  23. Ian

    Monte Carlo simulations are susceptible to what I call the Gi=Go phenomenon. Garbage in = Garbage out. I have no clue – have not read the paper so I really should not comment…but is is interesting that a planet should be there…

    GIGO is a problem for any model, not just Monte Carlo simulations. Also, the acronym is 50 years old and well-known, so please don’t act as if you’ve just personally invented it.

  24. Ian

    “Sid Meier was right!”

    Well, almost right. The planet in SMAC orbited Alpha Cen A, not Alpha Cen B.

  25. xav0971

    Let’s see here. 24,000,000,000,000 miles away. If a probe is moving at 35,000 miles per hour it would take 78,224 years to get there. Is that what speed voyager II is moving at? Let’s be reasonable, to get there in a century you need to go 27,378,507 miles per hour!! thats only 780 X faster. damn!!!! WE NEED WARP DRIVE NOW SCOTTY

  26. Sh!fty

    I’m no physicist but I think Gadren is right. As they get farther the video would appear to be slowing down (very very slowly). Yes, the feed would be “live” and the speed it takes to get here would be the same, but not the distance such speed needs to travel. Each instant of the video would be sent from farther out. Imagine the video lasts 40 years, which is the time it takes to get there, at 10% the speed of light (not considering acceleration and deceleration), then the first part of the video gets to us “instantly” but the last part gets to us 4 years later than when it was generated. So if it takes us 40 years to get there the video feed wouldn’t end until 4 years later (44 years). Am I right?

  27. RH

    “Well, almost right. The planet in SMAC orbited Alpha Cen A, not Alpha Cen B.”

    Buried in the arxiv PDF is that formation around the A star should be qualitatively similar to the B star. In fact, given the windows for formation they cite in their paper of 0.5-1.5, a habitable planet may even be more likely around A. They just didn’t simulate that (yet?)

  28. Glenn

    So, I read the paper as best I could in my borderline scientific illiteracy, and it’s clearly discussing planets around the B component.

    I can’t tell if they tried the A component and didn’t get planets, or if they didn’t try.

    Anyone more literate able to explain?

  29. RH

    “I can’t tell if they tried the A component and didn’t get planets, or if they didn’t try.

    Anyone more literate able to explain?”

    Sure. They didn’t do simulations for B because the primary point of the paper was to show why we should be looking at B really heavily. A is more massive (among other factors) which makes it much harder to see a ~2 Earth mass planet at ~1 AU if we were to look with current technology. Hence, although they expect the final result to be nearly the same for A as B, they only did simulations for B because they thought they would be able to see that (and each of these runs took up hundreds of hours of computer time!)

  30. I always thought the people who would say “Alpha Centauri Can’t have planets” were making a logical leap without enough evidence.

  31. Glenn

    RH: Thanks. You posted your first comment while I was reading the article, or I wouldn’t have had to post mine.

    My person dream of ‘teh cool’ would be for there to be habitable planets around both components.

    Would make for an interesting story background…

  32. What about infinity of finite infinities?

    Infinite possibility born within every individual, whose time of life represents infinite possibility within a single finite time = 1 life.

    Or infinite variation of possible interactions in the finite time of 1 second, for an infinite series of seconds, each segment of 60 seconds in series a single minute, an infinite series of minutes, each segment of 60 minutes a series of 60×60 seconds in the finite time of a single hour, and so on.

    So there could also be a finite infinity of matter in motion within the life time of a single solar system.

    Or a finite infinity of energy within every E=MC^2 snapshot of time stopped in time.

    Every single time.

  33. Would the Earth-like planet be called “Centauri Prime”?

    Where’s Ambassador Mollari when we need him?

    J/P=?

  34. Titanium Dragon

    Well, its actually even more complicated than that you’d get 44 years of video footage from a 40 year voyage (relative to us). Yes, the video would slow down as we’d see it, but they’re travelling at 10% of the speed of light as well, which actually would slow it down even more. While they were travelling at 10% of the speed of light, the video frames would appear to us to be coming at a slightly greater than 10% slower rate because of time dialation.

    Basically, you’re adding a bit of distance between each frame, THEN you’re adding the fact that the frames themselves are being slowed down relative to us by the relativistic speeds.

    So yes, we’d get 44 years of video feed, and it would actually be slowest (in terms of time between frames) when they were travelling there, NOT when they actually got there and decellerated to base speed.

    Oddly, though, if you counted the frames you’d actually end up with LESS THAN 40 years worth of video.

    Yeah, relativity is weird.

  35. nfk

    @tacitusion – We’d send a probe to Alpha Centauri every few decades, each bigger and faster than the last one that would, along the way, pick up the previos probe. (Maybe as a light snack o.o)

    I agree that telescopes are our best and most practical way for seeing and learning more about these planets. I wish the Terrestrial Planet Finder wasn’t in funding limbo. I like the idea of mutliple small telescopes working together to produce images equal to that of much large telescopes. And being modular has certain benefits. Need better resolution, add another small telescope.

    @xav0971 – sheeesh, I’d hate to be that saleman. “This spaceship can go from 0 to 28 million miles per hour in just under a century. So, when do you want to start the paperwork?”

  36. asknot

    The link given states that the Alpha Cen system is fairly old and that A might be close to becoming a red giant. What would that do to any potential planets around B?

    And what would A turning into a red giant look like here on earth? How much brighter to naked eye observation would it get?

  37. asknot

    John Paradox:

    I’m pretty sure that Alpha Centauri isn’t the home system of the Centauri Republic in the B5 canon. (Centauri is their own name for their own planet). There is a human colony called Proxima, which might be a reference to Proxima Centauri.

  38. BlondeReb3

    I just saw an article about this on Yahoo! and rushed to this site to see if you had heard about it yet. In the Yahoo! article, the author stated that with a telescope one should be able to observe an earth like planet on Alpha Centauri (which goes against what I learned in my introductory astronomy course), that’s pretty cool!

  39. Chip

    In B5 lore I vaguely recall the Centauri were the first humanoid aliens the humans encountered and they immediately conned us into thinking they invented the jump gates.

  40. aporeticus

    # Gadren on 07 Mar 2008 at 3:57 pm

    Ken B, I understand that the video of them at AC would take 4 years to get here, and 2 years to get here from a point halfway there, etc.

    But would it still hold if we had a continuous “live” feed, not just packets of video sent at regular intervals from the ship?

    Each frame of the video is a packet. The frame rate of the video would be affected by the relative velocity of the sender and receiver. This is basically the Doppler effect. the distance itself wouldn’t affect the frame rate, only the delay of each packet. If the relative position remains constant, then the frame rate won’t change.

  41. KC

    Words fail me. This is wonderful on so many different levels. This has a huge potential in seizing the imagination of the public, and that can translate into new funding for telescopes, both optical and radio. SETI, too, for if a rocky planet can be detected just four light years away, everyone and his brother is going to want to know if there’s intelligent life there

    The downside is you can just about bank on a flurry of “saucers from Centauri” in on the woo-woo circuit.

  42. Tim G

    With breakthroughs in fusion propulsion, we could get there by the year 4000 and conceivably by the year 3000. Practical limitations on specific power and specific impulse would prevent an earlier arrival.

    Astronauts/embryos would have to be shielded by cosmic rays, either by propellant or magnetic field or combination.

    I once ran simulations of orbits of hypothetical planets in the habitable zone of the Alpha Centauri system using a ninth order symmetric multistep method. The eccentricities would change cyclically with periods of centuries but not in a profound way.

  43. Scorpious

    Tatooine, here we come.

  44. themadlolscientist

    “My vote goes to a planet loaded with hott sexy green babes.”

    Don’t forget the sexy green dudes! ;-)

  45. Eric

    I find it kind of uncanny how some of Star Trek really does relate to real life advancements…

    Who knows… maybe someone named Zefram Cochraine will devlop warp drive by 2070… then disappear to that planet.

  46. “Would the Earth-like planet be called “Centauri Prime”?”

    Because they are looking around the B star, you would have to call it “Centauri sub-Prime.”

    Can I interest you in buying a mortgage there?

  47. And astronomers on “Centauri Prime” are probably looking in their telescopes at this very moment and wondering if that yellow sun 4.3 light has a rocky planet.

  48. B5’s Centauri Prime is: 75 light years from Babylon 5.
    B5 is in the Euphrates Sector.
    The sun for the planet Euphrates is Tigris.

    From the A-Z Guide to Babylon 5.

    J/P=?

  49. andy

    The reason for the focus on Alpha Centauri B is that it is expected to be a much more stable star than Alpha Centauri A. The analogy is with a star called HD 69830, around which a system of 3 Neptune-mass planets was discovered in 2006 (typical habitability-hype-ridden article here). Alpha Centauri B has similar mass and enrichment of heavy elements to HD 69830. Since stars like the Sun are much noisier in terms of activity, such a system would be much harder to detect around the Sun or Alpha Centauri A.

    As for stability, that shouldn’t be a problem around either of the Alpha Centauri stars, and the extra heat from the second sun shouldn’t affect temperatures by more than a couple of tenths of a degree. Provided that the planets are not inclined from the binary orbit too much, they could remain stable for billions of years.

    The real issue in terms of habitability of any planets around Alpha Centauri is the problem of getting enough volatiles (e.g. water) to the planets – the binary orbit would tend to chop off protoplanetary discs roughly at where the “snowline” is expected to be. In addition, the eccentric orbit of the binary stars would help to scatter material outwards, restricting the possibility of transporting icy material from a hypothetical circumbinary disc to any terrestrial planets orbiting the stars.

    It may well be that Alpha Centauri could easily have planets of the right mass in the right place, but be too dry for water-based life.

  50. andy

    …plus, I like the way the space.com article has apparently reused an artist’s impression of a pulsar planet to illustrate an Earthlike world… see the beams zapping out of one of the Alpha Centauri stars…

  51. Grand Lunar

    @Andrew

    “Even with an anti-matter drive (which we can’t build), we could not get faster than .1 C. 4 light years away, at .1C takes 40 years. ”

    I think you’re underestimating the available speed.

    0.1 is only 10%. That’s a speed estimated for rockets using fusion for propulsion.

    From what I’ve read, for antimatter drives, max speed is between 50% to 80% light speed.

    And to be pedantic, we can’t build it with CURRENT technology.

  52. schneider

    There are 3 SMAC references before I could make one! Good Work!

    … now where did I put Zacharov’s Number? And what are Miriam and Yang up to?

  53. Tom K

    …Remarkably, what they found is that they got a terrestrial (rocky) planet about the size of Earth orbiting Alpha Cen B every single time, and in many cases was at the right distance from the star to have liquid water.
    ….
    It’s difficult to say what that would do for awareness of astronomy; I can’t help but think it would make a huge splash. First, to find a planet orbiting the nearest star, and second, an Earth-like planet… wow. Still, since the result is still only theoretical, it’s too early to get too excited about this.

    Note that when Phil says an Earth-like planet, that just means one that’s not a big gas giant like Jupiter-Uranus. In this context, Mercury, Venus and Mars are all “Earth-like” planets. Doesn’t mean they’re even remotely habitable, and being the right distance to have liquid water possible doesn’t necessarily mean it’s there.

  54. Can Hubble or Spitzer et. al. look that far away and get a good view or does the light from those two stars make seeing the planet all but impossible?

    Unfortunately, no — an Earthlike planet 1 AU away from Alpha Centauri B would be ridiculously faint. A back-of-the-envelope calculation suggests roughly 30th magnitude for the planet, at most 0.75 arcseconds away from the star.

    And what would A turning into a red giant look like here on earth? How much brighter to naked eye observation would it get?

    Red giants vary somewhat in absolute brightness, but on the average they run about 100 times (5 magnitudes) brighter than G-class main sequence stars like Alpha Centauri. See, for instance, this diagram: the giants (luminosity class III) run about 100 times the luminosity of the Sun, which is very similar to Alpha Centauri A in brightness. That would (at its current distance) make it a bit brighter than Venus.

    Of course, Alpha Centauri is moving, and by the time it goes red giant, we (well, long-removed descendants of us) probably won’t be able to see it anymore.

  55. tacitus

    Here’s a simple solution, “Astronomer”. If this blog annoys you so much, then don’t come here! Then perhaps you won’t come off as an arrogant prig.

  56. momo

    interesting post. until now I was under the impression that binary stars don’t allow for stable planet orbits (guess I picked that up when googling for sirius and dogons etc). probably you could elaborate on that?

  57. Ever read Aldrin’s “Encounter with Tiber?” It’s been a long time since I read it, but it poses the question of “what if intelligent A. Centauran’s visited Earth?” I do remember it as being a good read.

  58. Mike Torr

    So when do we get a visit from the “small furry creatures for Alpha Centauri, who were REAL small furry creatures from Alpha Centauri”?

    :D

  59. Mike Torr

    Oops. “from”.

  60. summit

    Well an earth size planet at that distance is going to be roughly 0.04mas across… can Hubble resolve that directly?

  61. sean d

    we need to be able to see for our selves and getting there who knows what will happen in the next 100 yrs but we have gone from steam engines,animal power,and the horseless carrige to space flight never say never we still understand very little on the grand scope of things

  62. FER

    If you were watching a video feed from a spacecraft travelling to some distant star at an appreciable fraction of the speed of light, the video would be slowed down by the “relativistic Doppler effect”. This can be thought of as a combination of relativistic time dilation and the ordinary Doppler effect which results from the changing distance of the source of the transmission (as someone else has already noted). While the Doppler effect is usually described in terms of very high frequencies of the spectrum of electromagnetic radiation (blue light turned red, e.g.), it also applies to the frequencies of all other apparent phenomena, whether its the frequencies of the mechanical operation of the spacecraft or the frequencies of biological systems. So an astronaut talking to the camera would appear significantly slowed down if you were watching a “live” feed. It is, of course, a simple matter to record the transmission and then review it at the correct speed later. And since any modern spacecraft would use some digital data stream rather than an analog “television” signal, observers on the Earth, apart from specialists in the process of data reception, would probably never be exposed to this relativistic Doppler effect. Indeed, since the data transmission rate would probably be reduced for other reasons (the decreasing strength of the signal at great range), even the data specialists might not recognize where the relativistic Doppler effect comes into play.

    The relativistic Doppler effect, incidentally, also helps to see why relative speed can never exceed the speed of light. Imagine a simple “pulsed” rocket where an astronaut fires the rockets on a spacecraft once every minute as measured by a clock aboard the spacecraft. At first, the spacecraft accelerates steadily as it recedes from Earth. As observed from home, just like those slowed “video” transmissions, the time between those rocket pulses grows longer and longer as the spacecraft gets closer to the speed of light in accordance with the relativistic Doppler effect. The acceleration of the spacecraft falls away to zero. Since the relativistic Doppler effect increases without limit as we get near the speed of light, the work required to accelerate the spacecraft by some increment also increases without limit. It is “as if” the spacecraft becomes increasingly resistant to changes in velocity, or “as if” it is growing in mass as it approaches the speed of light.

  63. FER

    One possibility for reaching a planet orbiting one of the stars in the Alpha Centauri system sooner rather than later is to build an exceedingly low-mass spacecraft accelerated by large fixed masers. What can you accomplish with a one-kilogram spacecraft? Ya never know until you try… But figuring twenty years to build the infra-structure and a thirty year travel time, we could be looking at imagees of that planet in just 54 years.

    This concept was originally proposed by the ever-creative Robert L. Forward and is known as “Starwisp”. There’s a nice article about this concept on Wikipedia: http://en.wikipedia.org/wiki/Starwisp

  64. Jeffersonian

    Thanx to this blog, I’m starting to really dig it when Astronomy and programmed sims collide.

    @Dennison
    “I discussed this with a friend who is a Native Centaurian”.
    Just kidding he didn’t really write that. But I had to look twice. Turn me on space man. (The centaurian was Paul).

    “This spaceship can go from 0 to 28 million miles per hour in just under a century”
    A Colo rancher is giving a Texan a tour of his land. When he gets to the top pasture they stop and look at the valley. “That’s it!”, says Colo. Tex sez, “sheesh, that’s it? I can get in my truck and drive all day and not reach my property line”. Colo sez, “Yeah. I used to have a truck like that.”

  65. Nigel Mellish

    @ james000777

    “Monte Carlo simulations are susceptible to what I call the Gi=Go phenomenon. Garbage in = Garbage out. I have no clue – have not read the paper so I really should not comment…but is is interesting that a planet should be there…”

    James –

    I’ve always wondered where this bit of “common wisdom” began. It is a statement that doesn’t really convey an understanding of the purpose of MC. MC is no more “susceptible” than Scientific Method or any other engine designed to test the accuracy a belief statement. Yet somehow, there isn’t this negative connotation about hypothesis testing when it doesn’t include probability theory.

  66. Mango

    Just one request for NASA: If we send a manned mission there, and one of the people signing up for the mission goes by ‘Sister Miriam Godwinson’, then, umm.. maybe tell her the wrong day for the launch.

    And ditto for Nwabudike Morgan, CEO of Morgan Industries.

  67. Jim

    “# james000777on 07 Mar 2008 at 2:47 pm

    Even if there is a planet, and even if it is rocky, and even if there is water, and even if we do find it, there is no way complex life could exist in a binary star system. Too unstable.

    Monte Carlo simulations are susceptible to what I call the Gi=Go phenomenon. Garbage in = Garbage out. I have no clue – have not read the paper so I really should not comment…but is is interesting that a planet should be there…”

    In addition to Ian’s chiding for taking credit for a phrase you didn’t coin, let me add this:

    There is no, I repeat, no reason that an earth sized planet cannot form a stable orbit around a member of a binary, or even trinary star system.

    The fact is simulations have shown that even if a member’s closest approach were, say, as close to us as the orbit of Saturn, the only appreciable effect would be that the other companion would act as a broom of sorts, much as does Jupiter in our own system, in deflecting asteroids and meteroids.

    Moreover, while initially thought that inner planets of either Centauri A or B may be “dry” for lack of comet impacts directed at them by nonexistant jovian companions, current thinking is that either companion may provide just such Kuiper Belt analogue orbital perturbations for it’s partner.

    As the Alpha Centauri system is .5 to 1 billion years older than is Sol, it’s a safe bet that in addition to having a stable set of orbits for hypothetical orbiting planets, the neighborhood should be even more free of “Stellar Driftwood” (credit to Welles) than is our own.

    I won’t hypothesize about simple life, much less complex, until we actually find Earth type planets there. But nor will I rule them out based on faulty information and uninformed pronouncements.

  68. StevoR

    Jim noted :

    “There is no, I repeat, no reason that an earth sized planet cannot form a stable orbit around a member of a binary, or even trinary star system.”

    True. Indeed, I’ve read one astro- news piece suggesting planets are actually more common around multiple stars and a number of exoplanets have been detected already around binary stars notably 16 Cygni.

    Then there’s this exoplanet : HD 188753 b or “Tatooine” – The first exoplanet found in a system with three stars. It orbits a G9 dwarf in 3.3 days with an orange dwarf binary beyond in an elliptical orbit ranging from 6 to 19 AU. The system lies 145 ly off in Cygnus.

    With Adelaide now having 9 days over 35 degrees celscius (dunno what that is in Fahrenheit – B*** hot!) today is one of those days I find myself wishing our Sun was less like Alpha Centauri A* and more like Alpha Centauri B! +
    —————————-

    * Alpha Centauri A = a G2 yellow dwarf, 1.7 x the Sun’s brightness,
    just a bit larger (10 % more massive), hotter and brighter than our
    daytime star.

    + Alpha Centauri B = a K2 orange dwarf, a bit dimmer, cooler and
    smaller than our Sun. It’s mass is 85 % of our Suns and it has 40 %
    of the Sun’s brightness.

    – Source : Page 15, Kaler, James B., “The Hundred Greatest Stars”,
    Copernicus Books, 2002.

  69. StevoR

    Correction : (& Phil Plait, pleaseklet us edit these! Please!)

    With Adelaide now having 9 days ** in a row (and with another week more heatwave to come) ** over 35 degrees Celsius

    (dunno what that is in Fahrenheit – B*** hot!) today is one of those days I find myself wishing our Sun was less like Alpha Centauri A and more like Alpha Centauri B!

    (But nothing like Proxima /Alpha cen C -taht’d justbe too cold! ) ;-)
    ——————————-
    BTW. Bad pun warning :

    Qu. What is a boxer’s favoutrite spectral type?

    Answer : KO! ;-)

  70. StevoR

    Check out this news link via NBc (?) :

    http://www.msnbc.msn.com/id/23594045/

    On how we might get to Alpha Centauri.

    If you can find it somewhere its also well worth reading :

    * Croswell, Ken, “Is there Life around Alpha Centauri?” (Article in) Astronomy magazine, April 1991, Kalmbach publishing Co.

    * Asimov, Isaac, ‘Alpha Centauri, The nearest star’, Lothrop, Lee & Shepard Company, 1976

    &

    * Dole, Stephen, & Asimov, Isaac, Planets for Man [sic], New York, Random House, 1964.

    Dole’s book includes a Rand study which estimated the chances of Alpha centauri A and B having habitable planets as :

    A = 0.054 (1 =certainty I think)
    B = 0.057
    & combined = 0.107

    Minor nitpicks or notes – Proxima Centauri is also Alpha Centauri C assuming its actually in orbit around theother two – which has been debated. If it is orbiting Alpha Cen A & B, its distance on average is the same as them – as Heinlein pointed out in his novel “Friday.”

    Alternative names for Alpha Centauri incl. Rigil (or Rigel) Kentaurus, Toliman & Bungula.

    My suggestion for planetary names should we find any is to use those alternative names ie. if we find four planets we call the innermost Rigil, the second from the star Kentaurus, the third Toliman and the outermost Bungula. Such system would make sense,continue tehtradition, be non-political and safe and also euphonious or nice sounding!

  71. Idle Thinking

    How long would it take to teleport to Alpha Centauri? Maybe, a probe could be sent there, on a 200 year journey, to build the teleport when it arrives?

  72. Idle Thinking

    Perhaps, the robot probe could be sent on its mission now. Instructions on how to build a teleport station being sent to the probe, mid voyage or at whatever date in the future human teleportation is invented.

  73. hello,
    i think so alpha centauri where humans exist is a galaxy of many planets where life exist and water as well.in my mind i can feel the people living in proxima centauri

  74. Frank Glover

    “Doesn’t anyone on here remember we sent a craft to Alpha Centauri a while ago? And it was lost?”

    Hmm. Would that be before or after the nuclear waste dump on the Moon exploded…?

  75. homer

    Alpha Centauri A probably has an Earth analog terrestrial planet at position 1.11 AU from star. This will very likely be a binary planetary system similar to the Earth-Moon pair given the abundance of iron and nickel and cobalt at that particualar placement. It appears that the formation of Earth analog planets is a self propagating process determined by rotational velocity of star and chemical composition of planetary nebula. Iron and the associated metals are most abundant at the position of nebula which develops into an Earth analog planet.
    Alpha Centauri B must also have an Earth analog -or Venus analog- planet orbiting it at position 0.73 AU. Between the two stars must be a field of asteroids extendding from 4 AU to 5 AU.
    Alpha Centauri A and B probably have other planets similar in stature to Venus and Mars and Mercury: however the range of terrestrial worlds can extend from arid salt desert planets to oceanic worlds covered entirely by water or water ice.
    The possibility of life on such planets is high: however, this must ultimately translate to an environment habitable by man – or an environment which man can associate with. Such as grasslands and evergreen flora.
    Other stars which must be investigated for Earth analog bodies are Epsilon Eridani and Tau Ceti.
    Epsilon Eridani has shown planetary features which suggest Solar System dynamics: numerous giant planets and asteroid rings. An Earth analog planet likely exists at position 0.64 AU. There is rumor that intelligent beings do live on a habitable planet in Epsilon Eridani which have insect like features. So, any attempt to entertain human expolration of that system would be useless.
    Tau Ceti is thought to be inhospitable due to the large number of comets and asteroids associated with that star system. However, this is exactly the reason why indepth study of planetary body in Tau Ceti must be pursued.
    The Earth analog planets of Tau Ceti must be sterile.

  76. Messier Tidy Upper

    @ ^ homer :

    Other stars which must be investigated for Earth analog bodies are Epsilon Eridani and Tau Ceti. Epsilon Eridani has shown planetary features which suggest Solar System dynamics: numerous giant planets and asteroid rings. An Earth analog planet likely exists at position 0.64 AU …

    Epsilon Eridani is probably less than 1 billion years & thus far too young to host intelligent life.

    Source : Page 46, Ken Croswell, “Epsilon Eridani : The Once & Future Sun” in ‘Astronomy’ magazine, December 1995, Kalmbach Publishing Co.

    Tau Ceti is ancient but metal-poor although there has been a massive disk of dust located around it according to Kaler’s Stars webpage on it.

    An Earth analog planet likely exists at position 0.64 AU. There is rumor that intelligent beings do live on a habitable planet in Epsilon Eridani which have insect like features. So, any attempt to entertain human expolration of that system would be useless.

    Um .. WHAT?! :roll:

    Even if there was an insectoid sentience living there – which is most unlikely given they haven’t had time to evolve & there may not even be an earth-like habitable planet (yet?) – how does it necessarily follow that we can’t explore there specifically *to* make contact with that other “rumoured” (source please?) sentient species and learn from it?

  77. Messier Tidy Upper

    Oops – the info. on Tau Ceti there was from Wikipedia NOT Kaler :

    In 2004, a team of UK astronomers led by Jane Greaves discovered that Tau Ceti has more than 10 times the amount of cometary and asteroidal material orbiting it than does our Sun. This was determined by measuring the disk of cold dust orbiting the star produced by collisions between such small bodies. This result puts a damper on the possibility of complex life in the system, as any planets would suffer from large impact events roughly ten times more frequently than Earth. Greaves noted at the time of her research: “it is likely that [any planets] will experience constant bombardment from asteroids of the kind believed to have wiped out the dinosaurs.” Such bombardments would inhibit the development of biodiversity between impacts.

    Source : Wikipedia’s Tau Ceti page

    I’d post the link – but .. moderation may never get around to it on a thread this old here & when I tried posting it with my name as the link before it wouldn’t work. :-(

  78. Christina

    “It’s possible that we may find such a planet in just a few more years.” And indeed we have! :)

  79. @ 81. Christina :

    Yes indeed. You beat me to it. :-)

    An Earth mass Hot(ter) Venus planet in a 3 day orbit sizzling around Alpha Centuari B which hopefully is accompanied by some more habitable planetary siblings as yet unfound.

    See :

    ALPHA CENTAURI HAS A PLANET!

    posted by the BA on the 16th October, 2012 at 4:45 PM and linked to my name for this comment.

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