Motherlode of potential planets found: more than 1200 alien worlds!

By Phil Plait | February 2, 2011 12:35 pm

Big news from the Kepler mission: more than 1200 potential planets have been found by the orbiting observatory!

This is incredible! Even though I was expecting a number like this, actually hearing it for real is stunning. In 15 years we’ve found about 500 planets orbiting other stars, but in the almost two years since Kepler launched it may have easily tripled that number! Now, to be careful: these are candidate planets, which means they have not been confirmed. But in most cases these look pretty good, and if these numbers hold up it indicates that our galaxy is lousy with planets. They’re everywhere.

And it gets better: of those planets found, 54 are in their stars’ habitable zones. Now, many of these are massive planets unlikely to be Earth-like, but the huge news is that five are near-Earth sized, and one is actually very close to Earth’s size!

If this pans out, then it implies there could be a million Earth-like planets in the Milky Way galaxy.

Holy Haleakala.

OK, so what’s the scoop here as far as science goes?

Kepler detects planets by looking for the tell-tale dip in light as they pass in front of their star, and the amount of light blocked tells us the size of the planet. Kepler is staring at one part of the sky, continuously looking at 156,000 stars for these dips. After 23 months in orbit, it now has a passel of 1235 candidate planets. Of these, 68 are roughly Earth-sized, 288 are bigger than Earth, 662 are roughly Neptune-sized, 165 are Jupiter-like, and 19 are larger than Jupiter.

Just these numbers themselves are pretty amazing. If 70 are Earth-sized and 20 are bigger than Jupiter, this means that planets like Earth are actually far more common than super-Jupiters! Up until now we couldn’t know this. In fact, far more super-Jupiters were found because they’re bigger and easier to detect. But now it looks like there may be many more Earth-sized planets than we thought.

Now, to be careful, these are not necessarily Earth-like planets: they may be very close to their stars and very hot, or may not have atmospheres, or may have poisonous atmospheres, and so on. But you have to realize that the more Earth-sized planets we find, the more likely it is that some, just by chance, are in their star’s habitable zone where liquid water can exist on the surface. And to be clear, "Earth-like" doesn’t mean it’s a twin of our home planet, just that conditions are similar — Mars is Earth-like in many ways, for example. But this news by Kepler means it’s far more likely that we’ll eventually find a planet that looks very much like our own.

Mind you, Kepler is only looking at a sample of stars that is one one-millionth of all the stars in the Milky Way. So it’s not totally silly to take these numbers and multiply them by a million to estimate how many planets there may be in the galaxy…

70 million Earth-size planets, and a million in the habitable zone of their stars. A frakking million. In our galaxy alone.

And while I have to note that some of these candidate planets may not pan out (they may turn out to be false alarms), as time goes on Kepler is likely to find more smaller planets in its sample, since the farther out they are from their star the more slowly they orbit, so more time is needed to uncover them. I strongly suspect that that million number is not likely to shrink. [UPDATE: the transit method employed by Kepler only finds planets that happen to have orbits edge-on as seen from Earth. That means it doesn't even see planets that have orbits tilted with respect to us, meaning that this estimate is almost certainly too low. And I was worried about overplaying this number! My thanks to Proesterchen in the comments for reminding me of this.]

Also, I don’t want to dismiss the massive gas giants either. As we see with Jupiter and Saturn, big planets can have big moons. If Jupiter orbited the Sun where Earth is instead of five times as far out, its moon Europa wouldn’t be a frozen world, it would be an ocean world as big as our moon! Saturn’s moon Enceladus is also a frozen iceball, and would be a liquid waterworld if it were closer to the Sun. That artwork at the top, done by my friend and planetary scientist Dan Durda, might look fanciful to you, but what Kepler is showing us is that there very well may be moons with views like this. Maybe not with plants and birds and other life, but I’ll be honest: this is starting to look less like science fiction and more like science.

During the Kepler press conference, planetary astronomer Debra Fischer called this "an incredible, historic moment." I agree! For years we’ve been making progress toward finding another blue-green world around another star, and this news means we’ve taken a really big stride in that direction.

For the first time in human history, we can look out into the night sky and actually and realistically and scientifically consider the presence of other Earths out there.

Science! I love this stuff.

Image credits: Dan Durda; NASA/Tim Pyle


Related posts:

- How many habitable planets are there in the galaxy?
- Does Gliese 581 g exist?
- Possible Earth-like planet found in the goldilocks zone of a nearby star

Comments (183)

  1. I guess that means we are one in a million!

  2. Robert

    It’s 2 degrees outside, I’ve been at work for three hours now and my feet are just starting to warm up, I won’t be eating a very big lunch today… but this news is going to keep me smiling all day. : )

  3. GebradenKip

    A million in our galaxy is still only 1 for every 100,000 stars, pretty rare. It also means that the mean distance between them might be higher than 100 lightyears. Still, chances are we are not alone.

  4. Chris

    Great news indeed! Come join the hunt and help analyze the Kepler data at http://www.planethunters.org…. Citizen science in action.

  5. Outstanding, but this is just planets that fall within habitable zones, right? So Earthlike could refer to Venus and Martian-style planets, too?

  6. Wow! This is so amazing. I wish I could live so much longer and be around when we actually find another planet that has creatures similar to what Earth has living on its surface.

  7. JR

    Im gonna start packing my bags!

  8. Proesterchen

    So are there statistics available that clarify what percentage of surveyed suns are likely to have planets in a plane that would allow them to be detected from Earth using the transit method? How much bigger could the number of potential planets grow just from the limited angle we’re currently checking?

  9. Pete

    So what effect does this have on the Drake Equation? Can we now get a good value for some of the variables?

  10. Scott (4) technically Mars and Venus are in the habitable zone of the Sun. Atmosphere matters! As do lots of other factors. That’s why I am cautious in this article and make sure I’m clear that Earth-size and Earth-like are different, and Earth-like doesn’t even mean a twin of Earth. Venus and Mars are both Earth-like, but still inhospitable to life.

  11. Jeremy

    Mind has been sufficiently blown. Thank you Kepler!

  12. Proesterchen (8): You are absolutely correct, and I’ll amend my post.

    As far as the actual fraction we’re seeing, I’m not sure. But it’s likely to be a small fraction of all possible orbits.

  13. Tony DeBlasio

    Wouldn’t the lower limit be 54 million planets in the habitable zone in the galaxy. And the larger planets, gas giants and such, could have habitable moons.

  14. frankenstein monster

    If Jupiter orbited the Sun where Earth is instead of five times as far out, its moon Europa wouldn’t be a frozen world, it would be an ocean world as big as our moon!

    Wrong. The low gravity and lack of magnetic field would cause it to lose all water in a few million years, leaving only a small dry lifeless rock behind.

  15. SC

    But any moons orbiting gas giants would really be poor candidates for harboring life, wouldnt they? We’ve seen from our own gas giants that they emit tons of radiation and attract swarms of asteroids and comets.

  16. JohnW

    This is actually kind of scary! All my life, I’ve never expected the question of extraterrestrial life to be settled. Not really – it has always been firmly classified in the category of speculation and science fiction. Now we are concrete, tangible steps closer to finding what might be out there. Some mental rearrangements might be in order (hopefully) soon.

  17. andy

    An Earth-sized planet in the habitable zone does not mean a terrestrial planet. We are finding that many of the low-mass planets have low-density, icy compositions: for a world in the habitable zone this would imply a planet with a deep ocean sitting on top of a mantle of high-pressure ice. It would be difficult to get minerals from the core of such a planet through the ice to the ocean, so such planets may well be watery but lifeless.

  18. CB

    How many transits must be seen before we call it a planet rather than a candidate? If I understand correctly, we have to see 2 transits for there to be any reason to call it a planet rather than a one-time passing object, it takes 3 to establish that there is a regular period, and ideally we want 4 to really nail it down. This is why the Kepler mission was designed for 3.5 years, to ensure we can see 3 transits of a planet in an earth-like orbit, and ideally 4. Even if that understanding is correct, I’m still unclear on when they switch from calling it a candidate planet to a planet.

  19. CountFloyd

    The Super-Jupiters would be a great name for a rock band.

  20. Gonçalo Aguiar

    I think that from 11 years I’ve been very interested in astronomy and NASA spacecraft missions, nothing has thrilled me more than the amount of new stuff we get from Kepler. Cassini was great too, but this is just inspiring to say the least. To think that we can now actually work numbers, make statistics to predict how much planets actually exist withing the Goldilocks’s zone is incredible.

    But I have a question:

    How did you end up with 1.000.000 planets in the habitable zone with Earth like mass and size in our galaxy?

  21. SkepticalMind

    The day we finally find an earth-like planet, without a shadow of a doubt ( Gliese 581 g, I’m looking at you! ), should be considered a world holiday. Just saying :)

  22. Richard

    Sometimes I have my doubts. The Earth is sick with wars, terrorist attacks, political uprisings, disease, famine, etc. But today seems like a good day to be alive and the best has yet to come. Thank you, Kepler!

  23. andy

    Wrong. The low gravity and lack of magnetic field would cause it to lose all water in a few million years, leaving only a small dry lifeless rock behind.

    The other issue is that the moons of the giant planets are not particularly massive and would find it difficult to hold onto an atmosphere as a result. Ganymede may be larger than Mercury but Ganymede is mainly icy, while Mercury is dominated by an iron core. As a result Mercury is more than twice as massive as Ganymede, and even a Mercury-mass planet would find it difficult to retain a habitable atmosphere. The icy moons may become more like very large comets under the red giant sun.

  24. noen

    So where is everyone?

  25. Nathan McKnight

    Yes, but *which ones* are the magic five!? I can’t find an answer on the NASA or JPL sites as to the stars they orbit or the estimated mass, distance, or surface temperature. Anybody out there have the data and the necessary skills for reading it, please post! :D

  26. Chief

    WOW. Guess I’ll have to change my post on Phil’s previous Kepler post where I said in the next several years… THAT was fast. Well done Kepler. (And the designers, software eng, astronomers, astro – etc. etc. etc.)

    So here we are 15 years after the first small steps from the first confirmation, we now have the beginning of our own Incyclopedia Galatica

  27. Miguel Lopez

    Does the data show how those planets are distributed? My guess is that planetary systems are not evenly and nicely found every X number of light years… but if, big IF, we can extrapolate that distribution across typical areas of our galaxy, and assuming we are in a fairly typical area of the galaxy, maybe we could predict how far away the closest Earth-like planets are, even if we can’t detect them by our current means.

  28. Gonçalo Aguiar

    Mercury is more than twice as massive as Titan, yet the Saturnian moon has a very thick atmosphere. I don’t get your point andy (22).

  29. Jonathan Dooley

    “Science! I love this stuff.”

    How can you not? This is fraking awesome!

  30. @noen (#22): Considering that our entire civilization isn’t detectable from the nearest star, I would say that if they are out there, they are still there wondering the same thing about anyone else that may be out there. :)

    Here is a document that I found discussion the detection range limits for different kinds of earth produced electro magnetic radiation:

    http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html

    The actual table is about 2/3 of the way through the paper. I put a copy of the table below:

    ————-+————–+———–+——–+——–+———–+
    Source | Frequency | Bandwidth | Tsys | EIRP | Detection |
    | Range | (Br) |(Kelvin)| | Range (R) |
    ————-+————–+———–+——–+——–+———–+
    AM Radio | 530-1605 kHz | 10 kHz | 68E6 | 100 KW | 0.007 AU |
    ————-+————–+———–+——–+——–+———–+
    FM Radio | 88-108 MHz | 150 kHz | 430 | 5 MW | 5.4 AU |
    ————-+————–+———–+——–+——–+———–+
    UHF TV | 470-806 MHz | 6 MHz | 50 ? | 5 MW | 2.5 AU |
    Picture | | | | | |
    ————-+————–+———–+——–+——–+———–+
    UHF TV | 470-806 MHz | 0.1 Hz | 50 ? | 5 MW | 0.3 LY |
    Carrier | | | | | |
    ————-+————–+———–+——–+——–+———–+
    WSR-88D | 2.8 GHz | 0.63 MHz | 40 | 32 GW | 0.01 LY |
    Weather Radar| | | | | |
    ————-+————–+———–+——–+——–+———–+
    Arecibo | 2.380 GHz | 0.1 Hz | 40 | 22 TW | 720 LY |
    S-Band (CW) | | | | | |
    ————-+————–+———–+——–+——–+———–+
    Arecibo | 2.380 GHz | 0.1 Hz | 40 | 1 TW | 150 LY |
    S-Band (CW) | | | | | |
    ————-+————–+———–+——–+——–+———–+
    Arecibo | 2.380 GHz | 0.1 Hz | 40 | 1 GW | 5 LY |
    S-Band (CW) | | | | | |
    ————-+————–+———–+——–+——–+———–+
    Pioneer 10 | 2.295 GHz | 1.0 Hz | 40 | 1.6 kW | 120 AU |
    Carrier | | | | | |
    ————-+————–+———–+——–+——–+———–+

    Notice that a one terawatt signal transmitted from a Arecibo sized antenna is required to reach a range of 150 light years.

    That inverse square law is a pain to work with!

  31. frankenstein monster

    Mercury is more than twice as massive as Titan, yet the Saturnian moon has a very thick atmosphere. I don’t get your point andy

    Three words. solar wind intensity.
    O.k. more words. It is much easier to hold onto a thick atmosphere in the frigid realms beyond the habitable zone where the sun is just the brightest star in the sky than in the babitable zone and closer.
    Temperature causes the atmosphere to puff up, more intense solar wind gnaws at it, and if the world is too small, the core solidifies, protective magnetic field stops, and replenishment by plate tectonics and volcanism stops after a while too. And after a million of years or so, all atmosphere is lost to space.

    So a small geologically dead world may have a thick atmosphere somewhere near saturn orbit and further away, but in the habitable zone, anything smaller than say 75 % earth would have a hard time to keep enough atmosphere at all.

  32. Brian York

    Actually, wouldn’t that make planets even more common than suggested by simply using the sky comparison, since Kepler can only detect planetary systems where the planets transit their star from our POV?

  33. Steve

    The probability that a planet is in the plane that Kepler will see it transit is 18%.

  34. philw1776

    The million projection is way too low. Kepler can only detect the well under the 2% of the planets lined up in the correct plane so as to appear to transit their star from here. Multiply the estimate by between 50 and 100.

  35. thelastrunner

    The critical question is: of the candidates selected for ground-based verification, how many were false positives and how may were confirmed?

  36. andy

    Mercury is more than twice as massive as Titan, yet the Saturnian moon has a very thick atmosphere. I don’t get your point andy (22).

    Titan is extremely cold, therefore the molecules in its atmosphere are moving more slowly than they would at room temperature and thus the rate of atmospheric escape is lower. The real issue is temperatures in the thermosphere: on Earth these can reach over 1000 K (thanks to various ultraviolet-absorbing species up there, which you’d tend to get on a watery planet thanks to photodissociation of water vapour), on Titan the thermosphere is far cooler.

  37. DrFlimmer

    So, actually, planetary systems like the one depicted in Firefly could be possible.
    Maybe, one day, Malcom Reynolds is up for another fight.

    Yes, I just watched an episode of that series on DvD, why do you ask? :D

  38. ObeyGiant

    This is awsome, but I have to wonder. Does this change your feeling about Contact at all? I know she went into the quintillion or higher with her math but it would be possible to be millions of planets out there as you say.

  39. TK

    Phil—as you say, Kepler launched almost 2 years ago now. But, it might be good to emphasize that this is just from the first 4 months of data. I can’t wait to find out what the first two full years of data tell us!

  40. JLE

    What’s even more interesting to me, is this is one small segment of the sky that Kepler is looking at, 105 square degrees, which is comparable to the area of your hand held at arm’s length. So if we expound the results just from this initial and yet to be confirmed findings, saying 80% of these finds are true, look at the ramifications to not only the Milky Way, but to M 31, and all the other spiral galaxies that are out there (we’ll bypass the elliptical galaxies for now) on the number of possible candidate planets that exist within a habitable zone of their star, and that are earth like! In this day and age, regardless of Drake, to assume we are alone in the universe is something I no longer can agree with. I find it far more likely that there is other intelligent life out there in the universe, than there is not. Doesn’t mean we get to meet them, but I’m sure they are out there. Kepler brings hope in a world that all too often seems to be going darker in terms of our abilities to both critically and creatively think.

  41. Jens Ulrik

    #26: So where is everyone?

    Enrico Fermi’s famous question. Remember though, that it took 4.5 billion years on our planet before a lifeform could even contemplate this question.

    Still, our galaxy is almost as old as the Universe according to this article – http://www.space.com/263-milky-age-narrowed.html – leaving plenty of billions of years for intelligent life from second or third generation stars to have ventured out, looking for “equals”. So I guess the question still stands.

  42. Lukas

    I often fall into a state of awe, thinking about other creatures inhabiting the universe in a distant galaxy somewhere, minding their own bussiness, doing their research and going to the movies.. but to imagine they could be just around the corner! Well it might be unlikely they go to the movies and such but any life form would blow my mind in its discovery! Thanks Phil for these news!

  43. Uscrulez2001

    Phil,

    I’m asking you because well… you might know someone with answers. In order to improve your habitable planet estimate we’d need to know:

    1. What percentage of possible orbital angles Kepler can detect? In other words, from a system being edge on, to a system being perpendicular to ours, what range can Kepler detect a planet?

    2. Is the distribution of system alignments in the galaxy completely random or are there preferred angles?

    I’m going to guess and say that no one really knows the answer to the second question. Hope I’m wrong.

  44. Awesome! Because I still plan to be a Starship Captain when I grow up, so I’m happy to hear I will have somewhere to go. Starfleet Academy will be accepting applications…when?

  45. Jens Ulrik

    By the way, I’ve participated as a Planet Hunter based on Kepler’s lightcurves (see http://www.planethunters.org) and am proud to say that after classifying over 2800 light curves, I’ve found 1 planet candidate and 1 eclipsing binary candidate not previously found by the Kepler team!

    For more info, see here: http://blogs.zooniverse.org/planethunters/2011/02/01/candidate-selection/

  46. Holy snortin’ George — this is AWESOME! My mind is struggling to stay inside my skull right now.

  47. Greg

    Proesterchen (8), Steve (35) and Uscrulez2001(45)

    There is some info on the probability of a planet being in the correct plane at:
    http://certificate.ulo.ucl.ac.uk/modules/year_one/NASA_Kepler/character.html

    It seems to be in the neighborhood of 0.5% for an Earth-like planet.
    (1 AU / Diameter of Sun) = 0.465%

  48. Joseph G

    Wow! History in the making, truly!

    @35 Steve: Yes, but an Earth-like planet in an earthlike orbit has a much smaller chance of transiting. The Wiki article on planet detection puts the odds at .47% (yes, I know Wikipedia ain’t exactly the sum of all reliable knowledge, but the science bits tend to be well-researched and unvandalized).
    But still, .47%! That means, for every Earthlike planet Kepler finds, there may well be 200 that it simply can’t see. It might not be unreasonable to think that about one star out of 150 has a terrestrial planet in its stars’ habitable zone! I know we’re dealing with a small sample size here, but still!…
    If my math isn’t horribly wrong, (it probably is), that means the estimate could go as high as 600 million (vaguely) Earthlike planets in the Galaxy!

  49. Okay. I also keep thinking about how fascinating Venus and Mars are. So even if that does include Venusian and Martian planets, it’s still Yay!-worthy.

    Nevertheless, the alt/bio artist inside me is mentally drooling!

  50. Gonçalo Aguiar

    Thanks for 33 and 36 replies.

    Now I shall ask another question:
    Based on current knowledge, is it possible for a moon orbiting a gas giant in the Goldilocks’s zone to harbor life?
    So until now we’ve seen: Moon’s gravity, expected surface temperature based on the star radiance and distance, solar wind density, presence of a magnetic field, …

    Can the distance form the mother planet influence habitability? If you get too close from the planet you would get more geological activity, due to stronger tidal forces, but since the moon is most likely tidally locked to the planet, the day would be shorter…

    Is there a compromise between these variables?

  51. Joseph G

    @ 42 JLF: One thing I love about this is that it looks like we’re starting to fill in the variables of Drake’s equation. I wouldn’t be at all surprised if scientists figured out a way to measure the composition of the atmospheres of these terrestrial planets within the next decade or so (they’ve already done so with gas giants).

    You know, I always figured that a space probe would discover the first extraterrestrial life, or maybe, if we’re lucky, a program like SETI. But now I’m going to place my bets with good Ol’ Fashioned (*snerk*) optical astronomy :)

  52. aleksandar

    I really hope this will help secure funding and actual timeframes for launch for Darwin, SIM and TPF. Stupid pointless Ares 1-X test launch could have paid for SIM and for a good portion of TPF.

    And I agree. “Where is everyone” is against starting to look like a very important question.

  53. Rory Kent

    Awesome!

    Coincidentally, as I was drifting off to sleep last night I thought about soon we were to discovering over a 1000 planets. And here we are.

  54. Brad

    There are many other factors besides planet size, distance from Sun (habitable zone), and atmosphere that will determine if life exists on another planet. There is the need for:

    * a moon which must be the correct size.
    * a magnetic field to protect the planet.
    * the host star must be of the same type as our Sun…and, by the way, in 50 years astronomer have yet to find a twin of our Sun.
    * tectonic plate activity
    * correct axis tilt
    * a Jupiter sized planet (at the right distance from “earth”) to protect it from comets/asteroids
    * correct orbital speed (may of Kepler’s finds are orbiting too quickly)

    There are many more……. the point is that each of these variables must be in place at the same time……this lowers the odds of other planets harboring life in as great a number as I’ve read here.

  55. “Where is everyone” is against starting to look like a very important question.

    I would slightly dissagree, and say that we are probably asking the wrong question all together. All too often, as humans we impart human motivations to other potential beings. While it seems to be an evolutionary drive to ensure the survival of a species, that doesn’t mean that any alien intelligence would have motivations anywhere close to ours. The “exploration” factor we seem to posses may not exist in other species. Their evolution may not have imparted it to them. We just can’t say. Also, as I mention in a previous post (#32), even our own civlization is neigh undetectable. Take into account the huge difficulties in brdging interstellar distances with any known or theororised technology (within the currently understood laws of physics) and the question seems to be irrelevant in the terms Fermi posed it.

  56. Jess Tauber

    Even if the rest of the galaxy is unihabited, it means that there is plenty of real estate out there for US to expand into- and earth enemies don’t ever have to see each other again. Humans being what they are, though, it is highly likely we’ll make new enemies to fill in the void.

  57. Unaspammer

    Something I’ve been wondering lately. The particular mixture of gases in the Earth’s atmosphere is largely a byproduct of the life forms infesting it, is it not? How likely is it that we could find a planet with a breathable atmosphere that is not already covered in life? Is such a thing even possible?

  58. Joseph G

    @ 49 Gonçalo Aguiar: There’s an excellent hard sci-fi series by Robert J. Sawyer called the Quintaglio Ascension Trilogy, about an intelligent saurian species (think sentient 6-foot tall Allosaurus) that lives on a moon orbiting a gas giant. The implications of life on a gas giant moon are explored to some extent in the books – the moon is tidally locked and orbits its planet about once every 12 hours.
    The series is sort of an allegory for the (human) Enlightenment, with various key characters refuting geocentrism (or whatever the Quintaglio version of that is called) and discovering optics, paleontology, evolution, psychology, and aerodynamics, along with all the religious and political backlash that comes with some of the discoveries.
    Not to give too much away, but one of the main characters (sort of their “Galileo”) discovers that the moon they live on is moving closer to its planet due to tidal forces, and will actually break apart on a geologically tiny time scale (a millenia or so at most). This kind of gives the sciences a kick in the pants as they begin to search for ways for future generations to escape to another world.
    Anyway, awesome books – some of the best sci-fi I’ve ever read, and I read a lot.

  59. Joseph G

    @32 Larian LaQuella: What about beaming? The inverse square law doesn’t apply if you have a beam (as Phil chillingly pointed out about Gamma ray bursts).

    As far as finding intelligent life, I’m not so sure I want to, at this point. Hollywood idealism be damned, I think it’s highly likely that any intelligent life will look at us the way the US looked at the Soviet Union during the cold war – suspicious of their motives and wary that they could attack pre-emptively. It wouldn’t be terribly surprising to me if a spacefaring species went around exterminating intelligent life just to ensure that it didn’t attack them later.

  60. Orlando

    @54: When you say “US”, do you mean you & me & others, or United States? :P

    I’m completely overwhelmed with these news, but I’d like to point at the fact that this is only the beginning, just one and a half years of observation, and only planets whose orbital plane is in line with us. We’re surrounded! :D DD

  61. @Joseph G (#57) You are correct (within limits as CB says below). However, to make that in any way effective, it helps to know what you are wanting to point at. If you look at human activity in this, how many messages have we actually sent? 19! That’s it! :o And the duration of those messages are incredibly short if you think about it. Almost like a WOW signal?

    http://en.wikipedia.org/wiki/Active_SETI

    http://en.wikipedia.org/wiki/Wow_signal

  62. CB

    @ 57 Joseph G:
    Technically it still does, because even the most tightly focused laser beam will still diverge, so it makes a cone not a cylinder. And the area of the base of that cone which the energy is divided over will be proportional to the square of the distance from the source. There will just be a different proportionality constant so it will degrade much slower than a signal that is expanding in a sphere.

  63. Joseph G

    @59 Larian: That’s 19 too many, if you ask me.
    First we develop space warships and terawatt lasers, then we go advertising our presence, that’s what I’d suggest…

    @60 CB: Oh I know, but it’s not nearly as bad as the inverse square falloff, is what I’m saying :)

  64. CB

    Also @ 57 Joseph G:

    Yes, it’s quite possible that aliens could want to exterminate all other intelligent life to protect themselves. It’s also possible that they could be slightly more compassionate, and merely want to enslave all other intelligent life to protect themselves. I hope we never run into either variety of Ur-Quan. :)

    And it is inverse-square, that was the only point I’m making. :)

  65. Scruffy Scirocco

    Don’t get your hopes up, folks. Planet the right size in the habitable zone are only two of the myriad things necessary to promote complex life. You need an oversized moon, a Jupiter-like planet the right distance away to deflect dinosaur killing asteroids, the right mix of elements in the primordial cloud (The Earth is blessed with having come from a particularly violent supernova nebula – where the stellar fusion went way beyond iron). Your star has to be the right size, you have to have a molten core to generate a protective magnetosphere or everything on the surface gets cooked in cosmic radiation. At some point the planet has to have experienced a snowball climate, there must be enough volcanic activity to reverse such a worldwide ice age through greenhouse gases.

    This is just scratching the surface. The odds against multicellular life having the precise chain of events to develop and survive are astronomical and are not normally considered in Drake’s equation. Earth is unique for all intents and purposes. any other earth like worlds are likely so far away as to be irrelevant.

    Read “Rare Earth” by Ward and Brownlee

  66. Paul S.

    Wow – this is great news! I wonder if and how soon it might be possible to learn a little more about some of the planets that are in the habitable zones. Is it possible to get at least a little information about atmospheric composition?

    First, of course, they have to actually confirm that the discoveries are real.

  67. Elli

    Yippie!!

    I’ve followed this blog for so long now, hoping something similar to this would finally be published…. =)

    What I wonder is, how do you actually get to these planets, if they exist? I mean, think if Kepler finds a twin-Earth, wouldn’t we want to visit it? And how would we get there? Isn’t it like billions lightyears away?

    Is there any actual, scientific theory on how to travel in space that actually might become realistic in the ‘near’ future? I guess you can’t just say ‘Jump’ like BSG….

  68. Michael Simmons

    If Jupiter orbited at earth’s distance would its magnetic field protect any of its moons from solar winds?

    It is possible via transit or doppler methods (applied to the host star) to detect an earth size moon orbiting a Jupiter sized planet at a habitable distance.

  69. Crux Australis

    That sound you hear is my mind, boggling.

  70. Richie

    We’ve only got the stuff on short orbits so far, it’ll take a couple more years of Kepler data before we start to get candidate planets that may be Earth sized and also orbiting on a similiar period to Earth.. So it’s probably a bit premature to be making galaxy-wide extrapolations based on the figures that have come in so far.

    Anything discovered in the habitable zone so far will presmably be orbiting close-in to a red dwarf star and we don’t know that this will necessarily give rise to suitable conditions for life, with them probably being tidally locked, etc.

    Still, what an exciting announcement, the exoplanet hunt is like the first boat landing on a huge uncharted continent.

  71. Michael Swanson

    @ 14. frankenstein monster

    ‘If Jupiter orbited the Sun where Earth is instead of five times as far out, its moon Europa wouldn’t be a frozen world, it would be an ocean world as big as our moon!’

    “Wrong. The low gravity and lack of magnetic field would cause it to lose all water in a few million years, leaving only a small dry lifeless rock behind.”

    Wouldn’t a Saturn- or Jupiter-like planet’s magnetosphere protect its closer moons?

  72. Georg

    Hello Phil,
    You wrote :

    Holy Haleakala.

    Maybe. But Kepler came from Weil der Stadt, he would say:

    “Heiligs Blechle”

    (Try to find some translation fot that :=)

  73. Jaz

    How do sun spots come into this?

    Does our sun produce large enough spots that they could get mistaken for Earth-like planet by some alien Kepler quarter of a galaxy away?

  74. Bronwyn Noble

    Damn! I’m with you, Tim! I love science — I’m not a scientist, but it’s filled my 60 years on this planet is adventure, excitement and fun! And that’s something I can’t even say for all the SciFi I’ve read all these years (and I’ve read a lot).

    Perhaps, someday, if something does smash in or blow up this planet, we’ll be able to get out there and actually seem some of those possible million planets.

  75. frankenstein monster

    *a moon which must be the correct size.
    * a magnetic field to protect the planet.
    * the host star must be of the same type as our Sun…and, by the way, in 50 years astronomer have yet to find a twin of our Sun.
    * tectonic plate activity
    * correct axis tilt
    * a Jupiter sized planet (at the right distance from “earth”) to protect it from comets/asteroids
    * correct orbital speed (may of Kepler’s finds are orbiting too quickly)

    falsehoods galore

    *where the correct size is anything from zero to the size equal to the planet itself ( and the only reason why it can’t get higher yet, is, that in that case we would call the planet ‘moon’ an the moon ‘planet’ )
    *any planet with a molten core will have magnetic field
    *where the same type means any main sequence star late F and below, and such stars are dime a dozen.
    * any planet of sufficient mass will have both plate tectonics, molten core and sufficient gravity to keep a thick atmosphere
    *where the correct axial tilt is literally any tilt from 0 to 180 degrees.
    *where ‘jupiter sized’ means ‘anything bigger than saturn’
    *it is physically impossible to have any other orbital speed than the ‘correct’ one

  76. Uite

    To join in the “what would happen if we ever met extraterrestrial intelligence” debate, I hate to be pessimistic, but we’d probably exterminate and or enslave them, if we’d get the chance, that is if they don’t get us first. It’s what we did to the wolves, arguably our closest competitors ecologically speaking, not to mention what Europeans have done to non-Europeans over the past five centuries.

  77. frankenstein monster

    Wouldn’t a Saturn- or Jupiter-like planet’s magnetosphere protect its closer moons?

    actually, the closer moons fly straight through the radiation belts of the planet and get orders of magnitude more radiation than they would get from the sun alone.

  78. Sam H

    I didn’t read all the comments, but I am now happier than I have been in a long time. I first read this in class (while we were winding down), and I didn’t even read the whole post – the headline is all it took to send me into a stream of pacing around the room constantly with a shocked grin, repeating “oh my god” over and over. When I settled down enough to read the rest of the post on the main page, I gasped and covered my ear-to-ear mouth in wonder, awe and joy when I read about the Earthlike planet statistics. The initial euphoria has now worn off, but my happiness still brims as I think about the possibilities of underestimation, and system tilt. But really – AT LEAST a freakin’ MILLION earth like worlds in only one galaxy out of the known 200+ billion!!! I know that intelligence is rare, that life is hard to come by, and the evolution of complexity could likely be chance, but really – a MILLION worlds!!!! :D :D

    Intelligence is likely rare, but they’re out there (my guess is not much more than around 1000 or so in our galaxy). And I don’t think odds against it in our own galaxy are too high, even with the Fermi paradox and all (who are we to say that everyone’ll want to build Von Neumann machines?!) Even though we can’t be truly certain in the God debate, even though life may be rare, even though intelligence may be rare, and even though CE3K was a UFO movie, I can emphasize with Spielberg and everyone touched by that film:

    We are not alone.

    This of course, will not solve the problem of the emptiness in all of us, nor the big questions of life, the universe and everything (likely not at all, 42 not withstanding). But in all our searching, there’s something right here, right now that makes the emptiness bearable.

    It’s each other. :D

  79. frankenstein monster

    It’s what we did to the wolves, arguably our closest competitors ecologically speaking, not to mention what Europeans have done to non-Europeans over the past five centuries.

    We got wiser. We protect wolves and we also gave up direct colonialism. So it is not unreasonable to assume that space traveling aliens will be wiser yet.

  80. frankenstein monster

    (who are we to say that everyone’ll want to build Von Neumann machines?!)

    Actually, everyone does. We already mass produce self-replicating machines. we just call the building process ‘pregnancy’.

  81. Mike

    I think I just peed a little.

  82. Atheist Warrior

    Lets hope that when other civilizations are discovered, that the American Republican political party is not in control. Otherwise they’ll immediately deem the other worlds as a threat to Christianity and attack them.
    -Seriously.

  83. While there may be plenty of other ‘Earths’ throughout the galaxy, let’s pray there’s only ONE Sarah Palin.

  84. Joseph G

    @66 CB: REgarding the inverse square thing, it applies to focused beams, too? I don’t follow.

    The Ur-Quan, that’s a new one on me. I’ve heard of the Borg, Thrintun, Kilrathi, Yuzhan Vong, Goa’uld, Daleks, Reavers, Flood, Cylons, and Tyrannids, but not those guys :P

  85. noen

    I don’t see how it would matter if an alien species were hostile or not. They have to bring it, and they ain’t doin’ that very easy. It’s kinda hard to conduct an interstellar war if it takes your hollowed out asteroid 100,000+ years to get to the front lines and everyone inside is stark raving mad when they get there.

  86. Joseph G

    @ 78 and 82: I think perhaps one of the most chilling takes on the situation is this, from the book The Killing Star by George Zebrowski and Charles Pellegrino. In discussing what happens when species gain the technology to accelerate masses to relativistic speeds:

    …The most humbling feature of the relativistic bomb is that even if you happen to see it coming, its exact motion and position can never be determined; and given a technology even a hundred orders of magnitude above our own, you cannot hope to intercept one of these weapons. It often happens, in these discussions, that an expression from the old west arises: “God made some men bigger and stronger than others, but Mr. Colt made all men equal.” Variations on Mr. Colt’s weapon are still popular today, even in a society that possesses hydrogen bombs. Similarly, no matter how advanced civilizations grow, the relativistic bomb is not likely to go away…

    We ask that you try just one more thought experiment. Imagine yourself taking a stroll through Manhattan, somewhere north of 68th street, deep inside Central Park, late at night. It would be nice to meet someone friendly, but you know that the park is dangerous at night. That’s when the monsters come out. There’s always a strong undercurrent of drug dealings, muggings, and occasional homicides.

    It is not easy to distinguish the good guys from the bad guys. They dress alike, and the weapons are concealed. The only difference is intent, and you can’t read minds.

    Stay in the dark long enough and you may hear an occasional distance shriek or blunder across a body.

    How do you survive the night? The last thing you want to do is shout, “I’m here!” The next to last thing you want to do is reply to someone who shouts, “I’m a friend!”

    What you would like to do is find a policeman, or get out of the park. But you don’t want to make noise or move towards a light where you might be spotted, and it is difficult to find either a policeman or your way out without making yourself known. Your safest option is to hunker down and wait for daylight, then safely walk out.

    There are, of course, a few obvious differences between Central Park and the universe.

    There is no policeman.

    There is no way out.

    And the night never ends.

  87. noen

    “We already mass produce self-replicating machines. we just call the building process ‘pregnancy’.”

    Yeah but installing the operating system is a pain and then there is the maintenance and uh… the poop. ;)

  88. @ Scruffy Scirocco (#67), I think Rare Earth has been pretty well debunked. All the conditions you mentioned are only necessary for OUR life on THIS planet. You are making an anthropomorphic principle fallacy.

  89. frankenstein monster

    and given a technology even a hundred orders of magnitude above our own, you cannot hope to intercept one of these weapons.

    Actually, all one needs to do to stop a relativistic missile is to put a modest dust cloud into its path. Each dust grain that it slams into, will explode like a miniature nuclear bomb, so the missile will turn into a quickly thinning cloud of plasma.

  90. Joseph G

    Weird, it only bolded the beginning and end…

    @ Noen: You don’t need to truck a big-ass battle fleet with to attack a planet-bound civilization like ours. Just get several hundred tons of iron moving at a good fraction of the speed of light, and you’ve got a boom that makes the K/T impactor look small. Put some navigational thrusters and a computer on it for terminal guidance, and you can relax, wait hundred years or so, and then watch the pop through your alien Ubertelescope while drinking a nice glass of whatever it is that evil aliens drink.
    I’m not saying it’d be easy, but there’s no in-person travel necessary, and it doesn’t take any new/unknown physics to get it to work.
    I’m gonna go hide under the bed now :)

  91. Brian Davis

    Coming late to the (fantastically interesting!) table, but still…

    There’s no fundamental reason I could see why you can’t have habitable moons of gas giants. Solar wind stripping? Doesn’t seem to bother Venus much, with no magnetic field… so clearly Earth-class moons, even without magnetic fields, have no problem retaining habitable (liquid-water-covering) atmospheres. Can you have Earth-class moons? We don’t know… but given what we understand of planetary formation, there’s no reason to think it’s impossible. Smaller moons? Well… Titan certainly holds an atmosphere, but as others have pointed out, it’s cooold… but for Jean’s escape, it’s the exosphere temperature that matters, and that does depend on composition, (Earth has a much higher exospheric temperature than Venus, for instance… though you wouldn’t no that looking at distance to the star, or ground temperatures). If solar wind stripping really *is* such a worry that you need a magnetic field, you’ve got one… from the gas giant. As to the radiation environment associated with this magnetic field, keep in mind that you have an atmosphere to protect a habitable moon, and atmospheres (especially on smaller worlds, given equal ground pressure) are pretty darn good at it. Not to mention on top of all this… who’s to say you can’t have a moon with a magnetic field? It may be rare (among Earth-sized and smaller worlds we have a whopping one example, Earth).

    Habitable moons may actually be the more *common* possibility. After all, small dim stars vastly outnumber sol-like stars, but the habitable zones there are so close in the resultant worlds should be tide-locked to the star… *unless* they are moons of gas giants. I suspect (and a lot of studies have shown) that worlds tide-locked to their star might be habitable, but it’s a long jump given the known examples (none).

  92. frankenstein monster

    Just get several hundred tons of iron moving at a good fraction of the speed of light, and you’ve got a boom that makes the K/T impactor look small.

    You need to expend grotesque amounts of energy to launch a relativistic missile so everyone will know about the incoming impactor.. And all he/she/it needs to stop it is to scatter a few thousand tons of dust to form a cloud too huge to avoid.

  93. CB

    @ Joseph G.

    @66 CB: REgarding the inverse square thing, it applies to focused beams, too? I don’t follow.

    Sure. Lemme try to explain it better. See, there’s no such thing as a perfectly non-divergent beam that resembles a cylinder. If there was, the area that the beam’s energy is distributed over — the end of the cylinder — would not vary with distance, and so neither would the intensity.

    Instead, real beams diverge, and form a cone. The father out this cone goes, the bigger the base of the cone. The sides of the cone are lines, so the radius of the base of the cone increases linearly with distance, which means the area of the base of the cone increases with the square of the distance. The beam’s energy is divided over that area, and thus the beam’s intensity is inversely proportional to the square of the distance from the source — that’s the inverse-square law.

    It’s just that because it is a cone instead of a sphere, the proportionality constant is much higher (Intensity = k/(distance^2) with much bigger k) and so the beam retains it’s strength much farther — but only by a constant multiplicative factor.

    This means that we’d still need an exceptionally strong signal for it to be able to reach distance stars. And it means that ideas like using lasers to beam power to probes in the outer solar system are going to require exceedingly powerful lasers to provide more energy than the Sun would.

    The Ur-Quan, that’s a new one on me. I’ve heard of the Borg, Thrintun, Kilrathi, Yuzhan Vong, Goa’uld, Daleks, Reavers, Flood, Cylons, and Tyrannids, but not those guys :P

    Yeah, it’s kinda like if the Borg who wanted to assimilate all life were just a subset of all Borg, and the nice guys.

    They’re just one of the awesome races from the early-90s game Star Control II, or the open source version that will run on your computer today, Ur Quan Masters — if you’re at all into retro gaming, highly recommended. :)

  94. Messier Tidy Upper

    Superluminous (beyond merely brilliant!) news. :-)

    (Typical, I have one night where I don’t check here & the BA posts this – and the other “Kepler finds a weird exoplanetary system” thread too. Oh well.)

  95. Nihilismus

    If you look at the geometric probabilities of transit here:

    http://certificate.ulo.ucl.ac.uk/modules/year_one/NASA_Kepler/character.html

    you’ve got to think the number of Earth-like planets in our galaxy inside their stars’ habitable zones must be at least  200 million, maybe even 1 billion.

    However.

    The volume of the Milky Way Galaxy is about 40 trillion cubic light-years. Even if there are a billion, that’s one per 40,000 cubic light-years, an area of space roughly 35x35x35 light-years in size. That’s a lot of space. We’re not even considering fractions of planets were (a) life arose, (b) became intelligent, and (c) developed technologies capable of communicating with us. Let’s say 

    1 in 10 where life arose

    1 in 100 where intelligent, complex life developed

    1 in 100 that developed technologies indicated above

    that leaves

    10,000 species capable of communicating with us but spread out to one per cube of space 1600 x 1600 x 1600 light-years in size. Our radio signals haven’t even made it 100 light-years. It could be thousands of years from now for Earth to even be noticed.

    And I’m not factoring in the age of the galaxy or the likelihood that many civilizations might have already come and gone.

  96. Brian Too

    Isn’t the lesson here that we ought to be careful about stating what we know? And don’t know?

    Obviously we do know some things quite well. However we over-extrapolate what we do know into what we really don’t know. We used to think that extrasolar planetary systems, if they existed at all, would resemble ours. Well maybe some do but we’ve now found a decent sample of those that don’t.

    So let’s not get all worked up about how we “know” what the conditions for life are. I’ve never understood why some seem to think that tidally locked planets (or moons) in the liquid water zone are unsuitable for life. Says who?

    Any atmosphere will greatly moderate the temperature gradients, a permanently inhabitable temperate belt zone will exist regardless, and this hugely underestimates behavioural adaptations. Ever hear of subterranean organisms? Going underground gives an organism serious protection against the heat (or cold) of the surface.

    And that’s just one example.

    We know a lot about Earth, what lives here and what is important to such life. Once we throw open the doors of possibility to other life altogether, our current role as catalogers of Earth life will be revealed.

    Otherwise we are just projecting ourselves on to the universe. That’s not a road to wisdom.

  97. aleksandar

    I think our very existence after a century of broadcasting is a good indicator there are no killer Von Neumann probes around. Especially since Great Silence would require them killing everyone in galaxy (so to explain as why we can’t detect anything; AND leaving us alive so we can ponder the problem).

    Further, mr. Pellegrino missed some bits. To launch RKKVs you will likely need significant Dyson swarm powering your launch boost laser; so with that big honking laser that can aim at a moving spaceship 100AU away… you can also blast the incoming RKKVs, at least enough to change their trajectories to miss your planets.

  98. amphiox

    There are many other factors besides planet size, distance from Sun (habitable zone), and atmosphere that will determine if life exists on another planet. There is the need for:

    * a moon which must be the correct size.
    * a magnetic field to protect the planet.
    * the host star must be of the same type as our Sun…and, by the way, in 50 years astronomer have yet to find a twin of our Sun.
    * tectonic plate activity
    * correct axis tilt
    * a Jupiter sized planet (at the right distance from “earth”) to protect it from comets/asteroids
    * correct orbital speed (may of Kepler’s finds are orbiting too quickly)

    In addition to the beatdown on this at #77, it should be pointed out that these factors are not independent on one another.

    Large moon, axial tilt, and tectonic plate activity are all related, at least on a planet earth sized and smaller, where large moon creating impacts thin the crust and promote tectonic plate formation (models of super-earths suggest that thin crust with tectonic plate activity is more likely due to the hotter core, without the need for a large moon).

    It is also not at all established whether any of the “services” these factors provide for earth are actually necessary for the development of life. We now know for example that of the 5 great mass extinctions in earth’s history, only one was even associated with a large impact, and many even larger impacts (as demonstrated by their craters) have occurred with no impact on the biosphere. Axis tilt which is modulated by a large moon stabilizes climate but it is not at all clear if a less stable climate really is prohibitive to the development of life (it may in fact promote life by increasing selection pressure over time).

    Life, once it arises, adapts too local conditions. To see a whole host of specific local conditions that life here is exquisitely fine tuned to does not mean that all these conditions are necessary for life to occur.

  99. amphiox

    If Jupiter formed in the sun’s habitable zone, it’s retinue of moons would be very different from what it actually has. They’d probably be made more of rock, like the terrestrial planets, rather than ice, since they’re going to form inside the snow line.

  100. Messier Tidy Upper

    @ ^ amphiox : If they had sufficient mass then perhaps they could support liquid water on their surfaces too right? Although the radiation may be the biggest problem unless such gas giant moons have some protective mechanism eg. planetary magnetic fields. Perhaps a Mars-sized moon of a superjovian exoplanet could support life? We don’t yet know enogh .. so many possibilities, so little data, still ..

    @87. Joseph G :

    The Ur-Quan, that’s a new one on me. I’ve heard of the Borg, Thrintun, Kilrathi, Yuzhan Vong, Goa’uld, Daleks, Reavers, Flood, Cylons, and Tyrannids, but not those guys

    Not so sure about the Reavers on that list – they were just insane humans not aliens! ;-)

    @21. SkepticalMind Says:

    The day we finally find an earth-like planet, without a shadow of a doubt ( Gliese 581 g, I’m looking at you! ), should be considered a world holiday. Just saying

    I second that suggestion. :-)

    I for one will be throwing a celebratory party and sinking a few cold beverages that day! 8)

  101. Messier Tidy Upper

    For those noting the Rare Earth book and its thesis; there seem to be two extremes on how common earth-like habitable worlds and life are in the cosmos. ‘Rare Earth’ is one extreme suggesting so many things have to go right for planets to be habitable and for intelligent life especially to arise that life is, well, very rare indeed. See :

    http://en.wikipedia.org/wiki/Rare_Earth_hypothesis

    for more via the usual fount of public knowledge, Wikipedia.

    OTOH, this text :

    http://en.wikipedia.org/wiki/What_does_a_martian_look_like%3F_the_science_of_extraterrestrial_life

    argues strongly and fairly well for the opposite view that life is varied, so ingenious and capable of existing inso many circumstances and strange ways that life is likely everywhere.

    (The latter is a good read which I’d recommend. Haven’t yet read the Rare Earth book to say how that compares as reading material.)

    My guess is that the reality will prove to be somewhere in-between.

  102. Messier Tidy Upper

    @90. noen :

    “We already mass produce self-replicating machines. we just call the building process ‘pregnancy’.”
    Yeah but installing the operating system is a pain ..

    Clearly you’re not doing it right then! ;-)

  103. Tom Callahan

    Goosebumps! Sounds like Star Trek was right, where pretty much every start the pull up to has some planets. Now where’s our warp drive!? Let’s go visit some of these!

    Ur-quan, that’s a name I haven’t heard in a while. There was a time when I could have recited the races and their ships from Star Control from memory. Androsynth, Ilrath, Spathi… dammit that’s all I can remember. Off to Wikipedia or maybe the attic.

  104. Tim G

    I recall reading Rare Earth and was a bit taken aback by the authors’ commentary about the lack of Earth-sized planets being discovered. The primary technique we were using for (looking for periodic Doppler-shifting of starlight) wasn’t yet sensitive enough to detect such planets.

    Hopefully, Kepler’s discoveries will help secure funding for the Terrestrial Planet Finder and future projects. I am amazed at how far the capabilities of astronomical instruments have advanced over the last few decades and I hope progress continues for the next few more.

  105. Messier Tidy Upper

    @85. Atheist Warrior :

    Lets hope that when other civilizations are discovered, that the American Republican political party is not in control. Otherwise they’ll immediately deem the other worlds as a threat to Christianity and attack them. -Seriously.

    Orly? “seriously” seriously?! Yeah, the Republican party and politically conservative Christian folks will welcome the news of an alien civilisation discovered light-years away by planning an invasion of it because, well, they’re just that evil? Sheesh. :roll:

    What a display of relevant, non-partisan, intelligent, sophisticated political “wit” there – not. :-(

    Seriously, I wouldn’t worry about those poor aliens. Those hypothetical beings will be saved by the fact that Obama and the Democrats will have destroyed the US manned space program so utterly we’ll be unable to even get our astronaut-soldiers into Low Earth Orbit without Russian or Chinese aid & permission. In fact, Obama’s presidency will have left the US (& Western world generally) so helpless the aliens won’t even need an invasion threat as he’ll have left America rolling over meekly for anyone and everyone – aliens, Muslims, Chinese or whoever – to do whatever they want with it anyhow. So if you wish to get political .. :-P

    Now can we forget about irrelevant politics for a minute and resume having a reasonable, interesting discussion about this awesome news please?

  106. Nick L

    @ Larian LeQuella (#32): That’s part of the reason why I’ve pondered if anyone has studied whether looking for an alien race’s nuclear testing might be a viable way to hunt for intelligent life. In other words, while an atmospheric/exoatmospheric nuclear detonation is very inefficient in terms of how the energy is distributed along the electromagnetic spectrum, it does have power behind it and some of our larger tests might have been “loud” enough to be detectable over several light years. That is, assuming that they are unique enough to be distinguished from the normal noise from our sun. At the same time, there is the issue of how brief the signal is.

    Of course, the amusing thing about this idea is that it might result in the most ironic answer to the Fermi paradox. Basically, an alien civilization heard our nuclear tests. However, the frequency of our atmospheric testing in the late 50′s-early 60′s made them believe we had a major war, with the remaining atmospheric tests after the Partial Test Ban Treaty came into effect being just revenge strikes against the remaining survivors, and they then didn’t bother to check if the line was really dead.

  107. andy

    You do realise that one of the main scientific advisors for Rare Earth is the noted Intelligent Design creationist Guillermo Gonzalez? It’s a stealth ID tract.

  108. amphiox

    Those hypothetical beings will be saved by the fact that Obama and the Democrats will have destroyed the US manned space program so utterly we’ll be unable to even get our astronaut-soldiers into Low Earth Orbit without Russian or Chinese aid & permission.

    But who needs astronauts? We’ll just launch robotic probes. Von-Neumann nukes and Berserkers.

    And then, perhaps a few thousand years later, the Benefactors will start stuffing waves of Ships of the Law down our throats, and the Repubs will have doomed as all.

    Doomed I say, doomed!

  109. Has anybody established that the Periodic Table of the elements, and chemical reactions of the elements and compounds, will be the same elsewhere in the universe?

    We know of it from observation — uhhh — the things we have observed. What might be more – or different – where we have not yet observed (upclose?)

  110. amphiox

    You do realise that one of the main scientific advisors for Rare Earth is the noted Intelligent Design creationist Guillermo Gonzalez? It’s a stealth ID tract.

    Yeah, but the primary author is Peter Ward, I think, and he’s certainly no creationist. Not that I don’t personally find the premise of the book quite dubious for a number of reasons, not just on the details of the science, but just on the basic logic.

    And I think Ward has gone on record later on saying basically the same as Messier Tidy Upper did, that the truth is probably something in between.

    But I think the scientific question is really about being “functionally alone”, rather than actually “alone” (as the difference between the two would not be discernable by science and would instead by a philosophical question). Would the frequency of intelligent civilizations in the galaxy be below a certain threshold where it would essentially be impossible for us to ever contact them or even find evidence of their existence. Like if there was another civilization in the Milky Way right now, but it was on the other side of the galactic core, obscured by all the gas and dust in between, would we ever be able to detect them, or them us? Or if there was on average one civilization per large galaxy, and there was one in Andromeda, could we have any hope of detecting them?

    Of course the threshold for detection ought to be expected to change with time. Maybe one day we really will be able to detect another single civilization in another galaxy.

  111. amphiox

    I hope we never run into either variety of Ur-Quan.

    Well, what about the nice original brown Ur-Quan, who befriended the Taalo?

    Androsynth, Ilrath, Spathi…

    Pkunk, Yehat, Shofixti, Human, Orz, Arilou, Thraddash, Slylandro, Umgah, VUX, Chenjesu, Mrnhrmrn(?), Chmmr, Syreen, Supox, Utwig, Druuge, Mycon, Melnorme, Precursors….

    Can’t recall any of the SCIII ones except the Eternal1s, but of course, Star Control III does not exist….

  112. Oh man, so much data to sift through among all these comments, and the post itself, but what an exciting discovery either way, as shown by the number of responders to it!

  113. Electro

    From #77 “any planet of sufficient mass will have both plate tectonics, molten core and sufficient gravity to keep a thick atmosphere”

    According to a recent documentary on the BBC called The Planets,
    all available evidence points to a total absence of plate tectonics on Venus and Mars.

    Could someone whose education reaches farther than mine, please explain, in relatively simple terms, what the day/night cycles would be like on a tidally locked, Mars sized body orbiting a Jupiter sized body at one AU from the parent star? I am having trouble wrapping my head around that one.

  114. Brian Davis

    I’d have to agree, “Rare Earth” was rarely accurate.

    The “large moon” fallacy was another one that always bothered me. Without our current Moon, the Earth’s obliquity variations would be large and chaotic… but that’s due to a resonance with Jupiter. If Jupiter was slightly bigger or smaller, or slightly further in or out, or if the Earth was spinning slightly faster or slower, or was slightly larger or smaller, or our moon was slightly closer or further out… we would still not be in resonance. In fact, the exact same paper (by Lasker) that pointed out the problem also mentioned that due to tidal evolution of the lunar orbit, the presence of a large moon will drive the Earth *into* large obliquity variations (a small moon would not have such an effect).

    This is among many many other problems with the book. As a technical peer-reviewed paper it would have been interesting, and probably shot immensely full of holes. But as a popular book, it avoid all that. Sigh…

  115. Brian Davis

    “Could someone… explain… what the day/night cycles would be like on a tidally locked, Mars sized body orbiting a Jupiter sized body at one AU from the parent star?”

    Depends on the orbit. If you put a Mars-scale body in Io’s orbit, and moved Jupiter to 1 AU, you’d end up with a “day” on that Mars-moon that was the same as its orbital period of 1.77 Earth-days. So you’d have, to first order, about 21 hours of light followed by 21 hours of dark – the Sun would rise and set. Jupiter, however, would not rise or set: it would hang at one location in the sky, visible over very slightly more than half the moon’s surface, forever invisible from most of the other half.

    This could be complicated by eclipses – depending on the inclination of the satellite-planet orbital planet to the planet-sun orbital plane, you could get anything from twice-a-year “eclipse seasons” to eclipses every day, depending on the geometry. These eclipses would last around 2.3 hours (IMS), but only ever occur on the Jupiter-facing hemisphere. That means during these “eclipse seasons”, you’d get more than a 10% decrease in insolation on one hemisphere relative to the other. That could result in a slight variation in “seasonality” on top of the more normal mechanisms.

  116. réalta fuar

    Debra Fischer is a “planetary” astronomer? I’m sure that’ll be news to her.
    One thing that was missing from the Kepler data is any mention of moons around
    the 49 planets LARGER than earth found in the habitable zones. It’s not immediately clear to me (without looking at the tables in the paper) how many of those planets are Nepture sized or larger, and thus may possibly have really big moons. This seems to indicate, at least to a first approximation, that Kepler is not going to be able to find many, if any,
    moons of giant planets in the habitable zones. That’s because the big planets found in the habitable zones so far already have multiple transits observed (at least 3, sometimes several more). Maybe moons WILL turn up thru TTV observations or as the data analysis gets refined (they’re still a factor of 2 or 3 of meeting their expected noise level). It seems pretty clear though that the number of habitable moons found by Kepler won’t substantially fractionally increase the number of potentially habitable bodies found.

  117. réalta fuar

    The chances of an earth twin around a solar type star (with a period of around a year) being seen in transit is about 0.01 (the ratio of the size of the star to the size of the orbit).
    Odds are somewhat better for planets in the habitable zones around K and M dwarfs, so that a good first guess at the total number of planets in habitable zones in the entire galaxy would be around a few hundred million to an upper estimate of around a billion. Note that because some of these stars are too young or have low metal abundances etc., this would be an over-estimate of the number of stars that could potentially have technological civilizations.

  118. réalta fuar

    Sorry, I hadn’t seen Nihilismus’s @98 similar and excellent comment (I assumed that the B.A. would have added that to the original post if such a comment had been made, bad assumption on my part). If one extends his use of the Drake equation with L = 10,000 years for the lifetime of a technological civilization and divide that by a nice round 10X10^9 years for the length of time the MW might have already been hospitable to life, you get 0.1 for the number of communicating technological civilizatons in the galaxy NOW. That’s quite a depressing answer to the Fermi Paradox. Of course, this comes with all the usual caveats about use of the Drake Equation. Still, lots of people think the chances of intelligence evolving are much less than 1/100, so even if L turns out to be much larger, the numbers balance and N still turns out to be depressing. This is not a good day for SETI.

  119. réalta fuar

    Oops, there’s a factor of 10 error in the above (just KNEW I would do that). N should be 0.01. Still factors of 10 in Drake Equation are pretty insignificant (not that I’m not kicking myself for it).

  120. Joseph G

    @ 95 Frankenstein’s monster: Regarding the first point, if you can manage to accelerate your missile before it gets within a couple light years or so of the target planet, it’d be very difficult for them to detect anything unless they were looking for it. Assuming some nifty fusion-torch-like engine, the vast majority of the energy would be headed in the other direction.

    As for stopping it, you won’t have all that much warning. The furthest probe we’ve sent into space is about 15 light-hours out. If the missile is coming in at, say, half C, and you see it all the way out by the heliopause, that gives you less then 15 hours to get your “shield” in place. And even if you do throw some dust in the way of the incoming missile, you’ve now got a cloud of hot plasma, with, say, half the speed but twice the mass, coming at you. I don’t know exactly how far away out dust shield would need to be for the cloud of plasma to dissipate to levels that won’t fry our atmosphere, but given the speeds involved, I’m guessing very far indeed.

    @79 Frankenstein’s monster: actually, the closer moons fly straight through the radiation belts of the planet and get orders of magnitude more radiation than they would get from the sun alone.

    I was wondering about that. I wasn’t sure how far out the worst of that trapped charged particle radiation was in relation to a gas giant’s moons.
    And unfortunately, if you want your moon to have an orbit that gives you an earthlike day/night cycle, it looks like you need to be quite close to that planet. IIRC, Jupiter’s second closest major moon has a 1.7 day orbital period, or something like that.
    Do you happen to know, are all Jovian moons tidally locked, or just the ones with the low orbits?

    @96 CB (re inverse square law in beams): Ohohhhh, I see. Thanks for explaining that.
    See, I told ya I was lousy at math :)

  121. Joseph G

    Damnit, why do all the best discussions happen when I’m away (or sleeping)? I have to get to work soon, and I’m still reading!
    *sob*

  122. I’m not sure if this has been mentioned before (sorry, I don’t have the time right now to read all the responses) but isn’t the actual estimated figure a lot higher than about a 1.000.0000 earth-size planets in our Galaxy since you haven’t factored in the way Kepler looks for planets?

    A.f.a.i.k. Kepler only sees planets that pass directly in front of their mother star, so it simply can’t see about 99 out of every hundred planets (or a figure somewhere in that ballpark at least). This implies that for every earth-size planet it is able to detect, there are 99 undetected ones still around. Which means there could be about 100.000.000 earth-size planets in our Galaxy. Now there’s a number to get exited about! The next one might only be about 20 ly’s away :)

    Or is my reasoning flawed?

  123. The Beer

    @ #121 – Brian:

    I was reading your answer about what the day/night cycle would be like and I imagined if there was intelligent life there.

    Imagine a civilization that lives on the OPPOSITE side of the Host Planet? They develop to the point of travelling to the other side then one day WHAM! The see the huge freakin’ ball in the sky?!? Maybe they had heard legends about it or maybe completely ignorant. But THAT would be interesting!

  124. I think your estimation is way low, Phil.

    According to my calculations, a planet in an Earth-like orbit will have a roughly 0.3% chance of being lined up correctly so it transits, which translates to about 450 stars of the Kepler survey. So if there are 5 Earth-sized planets actually there, that means about 1 out of 90 stars will have and Earth-sized planet in its habitable zone. That means there should be a few BILLION Earth-sized, Earth-orbiting planets in the galaxy (give or take an order of magnitude).

    That means there’s probably another one within 20 light-years of here. WOW

    Edit: Looks like 129.) Jules Stoop concurs!

  125. A further thought: out of these 450 stars, 54 have at least SOMETHING in their habitable zone, which would imply 1 out of 9 stars in the galaxy. So if we’re counting moons, that might bump up the estimate of habitable worlds considerably.

  126. jfb

    “Where is everyone?”

    It’s only been in the last century that we’ve been able detect EM waves over interstellar distances. It’s quite likely that we may have missed some; if an advanced civilization went dark for whatever reason just 150 years ago, we’d never know about it.

    It could be that there’s only one intelligent civilzation around at any one time, at least within the neighborhood, meaning we’re it for the moment.

    It could also be the case that other planets are lousy with intelligent life, but for whatever reason just aren’t using EM radiation to communicate, or are using frequency bands that we aren’t looking at.

    It may also be a matter of environment: imagine a seagoing critter like dolphins or whales, but with intelligence on par or superior to humans. How would they begin to build equipment to send out radio waves?

    We make a lot of assumptions what alien intelligence must be like and how it would communicate. It’s quite likely that many of those assumptions simply don’t apply.

  127. @56: Where on earth did you get the idea that scientists have never found a “twin” of our sun? Actually, there are quite a few solar twins (provided you don’t mean an exact duplicate, which would be silly), as well as a larger number of “solar-type” and “solar analog” stars. Currently the closest known solar twin is 45 light years away, and the most similar twin is 217 light years away, with several “siblings” in between. Sun-type stars are much less common than red dwarfs, but they’re not unusual.

    http://en.wikipedia.org/wiki/Solar_analog

    @98: You’re distributing these civilizations evenly across the entire volume of the galaxy, when it’s much more likely that they’ll be concentrated within the donut-shaped habitable zone, which is still large but considerably smaller.

    Also, a lot of people keep overlooking von Neumann probes, despite the fact that they’ve been mentioned numerous times in this thread. They don’t require FTL travel, aren’t limited by the lifespan or frailties of organic meat, could outlast the 10,000 year civilization lifespan (which is based on a sample size of one and therefore a highly dubious number anyway), and aren’t that much of an extrapolation from current technology. They’re thus a pretty crucial part of the Fermi Paradox, and one that’s hard to dismiss. Even the vast distances implied by 10,000 civilizations spread across the galaxy and billions of years would be bridgeable once just one of those civilizations manages to spawn them. We’re unlikely to be the first parents.

  128. CB

    Re: The bullet list of things life-bearing planets “need”.

    A lot of those are speculative at best. For example, afaik the jury is still out on whether Jupiter is a net positive or negative with regards to potential impacts. Sure it deflects and captures some, but it also disturbs the orbits of others that would otherwise not be a threat, like drawing objects from the Oort cloud into the inner solar system. And we almost certainly have Jupiter to thank for the existence of any other main asteroid belt object that might threaten us, by preventing it from accumulating into a planet long ago.

    Re: Drake Equation and the Fermi “Paradox”.

    The thing with the Drake Equation is that there are still so many numbers in it that we have little idea of. I love Kepler’s and other projects’ contribution to the early factors in the product, but go beyond that and it’s all mostly guesswork. There are reasonable numbers you can plug in that mean there should be tons of civilizations, or that it’s not expected that there’d be another in our galaxy, or even where we are a statistical fluke.

    The thing is, while the Drake Equation is an interesting tool for at least understanding the factors that go into figuring out the odds, the Fermi “Paradox” is a paradox in name only and not that interesting to me. The reason is that it hinges on the question of “Why haven’t we observed and noticed undeniable evidence of aliens already?”

    Which is a ridiculous question to ask when our observational capabilities are so limited that we’re only just gaining the ability to find worlds around other stars, despite them being apparently quite common. Which means they would have had to come to us for us to notice them, and if we exclude FTL then that’s not necessarily likely. Someone usually proposes that if an ancient civilization decided to send out Von Neumann probes to explore the galaxy (throw that into the Drake equation) that one would be here. And again, our capabilities are limited enough, how can we be sure there isn’t? A gigantic space observatory out around Pluto could study our solar system while crunching up rocks to make more of itself, and yet we’d have to be extremely lucky to find it assuming it’s possible.

    So I’m just not seeing how it’s a big mystery that demands an answer — even given Kepler’s result of there being many planets out there.

    Re: 134 Charles:
    See, but that’s my point “just one” civilization could be the total expected number per galaxy.

    But even if there’s more than that, you have to factor in the odds that they do actually decide to make them, that they do succeed (and the project isn’t canceled due to budget cuts), that they work reliably enough to cross the galaxy… we’re already to the point where “just one” isn’t necessarily “just” anymore…

    And then they would have had to start long enough ago that they’d have a reasonable chance of having arrived to our part of the galaxy already. What if this “just one” civilization only started fifty million years ago and the probes are basically just starting their voyage?

    And then we’d have to assume that we’d assuredly see them if they were here already!

    So personally, I find the Von Neumann probe argument pretty easy to dismiss, at least to the extent that it’s supposed to put the paradox in Fermi’s Paradox.

  129. The downside is that the more Earth-like planets are found, the more the combination of the Drake Equation, Fermi’s Question and Gott’s Copernican Principle force us to conclude that our lifetime as a species will probably not be long.

  130. @135: I think you’re missing the point of the FP. It’s not a ridiculous question to ask, because you’re assuming that we’re the active party, but our detection ability isn’t the most important limiting factor. First of all, VN probes don’t have to be likely, given the number of times the dice should be rolling, because you only need one positive. So either there are no nearby probes (or analogs thereof), in which case the question is about the existence of a Great Filter (or filters) which we’d better watch out for, or there are probes but we haven’t detected them yet, in which case they’re avoiding us for some reason or another and the question is about the reason why.

    It may be an academic question for the moment, since we’re unlikely to have definitive answer anytime soon. But the ultimate resolution to the question is likely to be very important someday, unless we just stupidly self-destruct on one of the Lesser Filters.

  131. CB

    @135: I think you’re missing the point of the FP. It’s not a ridiculous question to ask, because you’re assuming that we’re the active party, but our detection ability isn’t the most important limiting factor.

    Maybe I am. I thought the point of the FP is to take the fact that we have not undeniably witnessed the existence of aliens and relate that to a statement on the existence of the aliens themselves or the lifespans of their civilizations.

    I’m not assuming we’re the active party, I’m observing, correctly, that we cannot with any degree of assurance say that there isn’t a probe in our solar system right now. It doesn’t matter if it’s the “most important” limiting factor, so long as it is a sufficient factor to make it impossible to draw any relationship between our lack of observation and whether aliens exist. Which it is — our lack of observational ability is sufficient explanation for our lack of observations all on its own. There is no paradox.

    First of all, VN probes don’t have to be likely, given the number of times the dice should be rolling, because you only need one positive.

    You only need one positive on every single factor in the Drake equation, plus the additional ones we’re adding, which include a relationship between age and distance that makes it possible for the probes to have reached us.

    For a subset of very reasonable values in the Drake Equation, this would not have been likely to happen at all. Certainly not to the point where the mere odds of it happening are so good that it not happening is a mystery with any deep implications.

    So either there are no nearby probes (or analogs thereof), in which case the question is about the existence of a Great Filter (or filters) which we’d better watch out for,

    But again, there’s perfectly feasible scenarios where the “just one” civilization to do this actually did it, but the probes aren’t here yet. No Great Filter is needed to explain it.

    or there are probes but we haven’t detected them yet, in which case they’re avoiding us for some reason or another and the question is about the reason why.

    They wouldn’t have to “avoid” us, they’d simply have to be positioned adequately to see everything they want to see, yet not be readily visible to us. They could have a space probe that makes the combined power of every human-made telescope and instrument put together look like a toy magnifying glass from a supermarket gumball machine, easily able to study every body in the solar system extensively yet still be extremely difficult if not impossible for us to detect. Personally I think it would make sense for such a probe to stick to the outer reaches of the solar system, since it would make it easier to send the next copies on their way without having to escape the solar system’s gravity well.

    There’s lots of speculation we can undergo about hypothetical aliens and their hypothetical probes.

    Fact remains: There’s no paradox. There’s no mystery. It’s only a mystery if you assume that we must surely be able to see aliens if they existed, but that’s just not true.

  132. frankenstein monster

    egarding the first point, if you can manage to accelerate your missile before it gets within a couple light years or so of the target planet, it’d be very difficult for them to detect anything unless they were looking for it.

    Assuming some nifty fusion-torch-like engine, the vast majority of the energy would be headed in the other direction.

    Forming a huge plasma jet that radiates across the entire electromagnetic spectrum in all directions, like a miniature quasar.

    it’d be very difficult for them to detect anything unless they were looking for it.

    Astronomers are 24/7 out, hunting for new/odd phenomena. A gigantic plasma jet would stand out like a sore thumb. You would have to be very far to miss it. And why one would waste such amounts of energy to attack someone hundred lightyears apart and commit a planetwide genocide two or more centuries in the future ?

    As for stopping it, you won’t have all that much warning. The furthest probe we’ve sent into space is about 15 light-hours out. If the missile is coming in at, say, half C, and you see it all the way out by the heliopause, that gives you less then 15 hours to get your “shield” in place.

    Wrong. Relativistic missiles are even less maneuverable than a falling brick.
    If you saw it departing, you will know almost exactly from where and when it will come. You could put the dust cloud in place years before the missile actually arrives. And you could use the dust even before you see any missile fired your way. Just smack two asteroids against each other an fill the entire solar system with fine dust from the collision. It will work like a cosmic speed bump. Slow ship will pass unharmed, but at relativistic speeds it will be impassable because the power the front shield of the ship will have to absorb goes up with velocity cubed.

    Do you happen to know, are all Jovian moons tidally locked, or just the ones with the low orbits?

    the big ones are for sure. don’t know about the small ones…

  133. Joseph G

    @130 The Beer: That’s pretty much what happens in the Quintaglio trilogy. The continent everyone lives on is on the side of the moon that faces outward. When sailing ships were invented, the planet was first thought to be the face of God.
    It’d be one helluva sight, I’m sure!

    @CB: Just to open yet another can of worms, are we even certain that VN probes are possible (or at least plausible)? What if your probe requires gold or platinum, or something, and the rock it lands on doesn’t have any? Self replication is hard enough, but even if someone hauled a (presumably refrigerated :D ) KBO down to earth, would we be able to build a probe out of it?
    I mean, I know the relativistic missile sounds quite science-fiction-ey, but in principle it’s just a brute-force energy-dumping approach (like a vehicle accelerated by a stationary laser) – a whole lot simpler then an intelligent, self-replicating probe.

  134. GP

    A great discussion going on here…

    I agree it is interesting to discuss the possiblity of alien civilizations, life on moons etc..

    But one important aspect is the simple fact how this changes our view of the universe, our existance etc. Since I can not say I have an extensive knowledge about this topic, here are my questions, stuff I want to here more about. Hopefully someone will “bite” :)

    It is one thing to assume or statistically calculate and make an estimate there are other solar systems out there and there must be a certain number of “earth like” planets. It’s another thing to actually confirm and observe them. Practially – we are far away from being able to reach those worlds in any way , so a lot of discussion (what about the the dangers, contact with other civilizations, are they and where are they etc…) is fascinating, but probably influenced by Hollywood a bit :)

    For me it is more about the fact how scientific and non scientific communities are going to be influenced. Remember when Earth was flat? Or the center of the universe, or the Sun was the center? Or our galaxy was everything there is? This has a potential to represent such a change. In 10 years we are going to live in “different universe” Funding for further exporation of good candidates is going to be there (because now we proved they are there), common people are going to get used to the idea about the actual alien worlds and how they look. Encyclopedia galactica is starting to actually fill in with detailed data on worlds. Even simple video games might start using actual systems :) and “populate” them :) . (Yes I think tha tis important – everything that goes in “public domain” (people who don’t read blogs like this one is) is important.
    Is it just a matter of time before we get good enough and detect acutal life signs (if there are any) in one of these places? This would be the greates discovery in history. EVER. Just one frakking small signature that indicates life…
    Even if we are not able to detect life (big prize) don’t forget how interesting planets in our solar system are. What about “alien” worlds?

    Anyway, it would be great to see more info or discussion on these topics. It’s interesting to talk about alien civilizations, first contact, Fermi paradox, Drake’s equation etc…but how about finding that one place with oxygen/carbon signatures in atmosphere first?
    How about talking about potential diversity of planets we find even if they don’t harbor life (do you realize how our solar system is still fascinating and we are still finidng new/exciting stuff). So many alien planetary systems are completely different then ours and fascinating by themselves. Imagine you get to explore one (just one!) of those even if it does not have signs of life!

    Also once we are “done” observing and we can’t get more data from were we “stand”, what then?
    Do you think we are ever going to be able to achieve “FTL” (in widest sense possible). Is that possible at all even thoretically? Or are we going to start sending probes…that will take 1000s of years to get there to those interesting places that shows signs of life?

  135. Tyler

    thanks for the intelligent and on-point discussion concerning the feasibility of habitable gas giant moons, a topic I have been interested in for some time. To answer one question asked above, most large solar system moons except the ‘irregular’ outer gas giant moons are tidally locked with their primaries. One exception I recall is Hyperion, which is chaotically influenced by nearby Titan and is also relatively small (more massive bodies lock more quickly than less massive ones).

    I’d be curious to see if anyone would like to take a crack at describing the day-night cycle of a gas giant moon which is *not* tidally locked…?

    I also recall that all of the Galilean moons orbit within the magnetosphere, affording them protection from the solar wind. However of course the magnetosphere also creates the famed radiation belts – though I do not remember how widespread these are or where they are located relative to the inner moons. I know we’re assuming a protective atmosphere, but aren’t these belts much stronger than earth’s? Would a typical small-but-habitable planet’s atmosphere be sufficient protection from such intense radiation (if the belts are in fact in the same orbital region as the moons)?

    thanks again for the thoughtful and wide ranging discussion.

  136. Joseph G

    @ Frankenstein’s monster: Astronomers are 24/7 out, hunting for new/odd phenomena. A gigantic plasma jet would stand out like a sore thumb. You would have to be very far to miss it. And why one would waste such amounts of energy to attack someone hundred lightyears apart and commit a planetwide genocide two or more centuries in the future ?

    I still think it could be finished accelerating before it got close enough to detect from the plasma plume (again, I’m thinking about our current technology). As massive as the energy requirements are, it’s nothing compared to the emissions from a star, and there are red dwarfs that are only a few light-years away that are only visible with our best telescopes.
    There’s also the laser-propulsion route, but that’d probably give even more warning :)

    Still, there’s got to be a limit to how far away a ship could be detected with our technology.
    And it’s a big sky – one of the reasons Eris was discovered decades and decades after Pluto, while being of similar size, is that its orbit is inclined to the ecliptic, and not a lot of people were looking for anything that far from the ecliptic.

    As for the second question: Paranoia. We can be pretty certain that any species out there is going to be concerned with self-preservation. Whether their culture also promotes values like tolerance or cooperation or trust, that’s impossible to guess.

    With regard to “dust speed-bumps,” you’ve got me there. Hmm. There are tons of variables – how much lead time you have, how thick the dust is, how well the missile’s trajectory can be calculated, what it’s made of, whether it has a similar cloud of dust traveling with it to help it through obstacles like this. I’m not sure who I’d even ask. Phil does have a knack for describing “energetic events,” but this seems kinda speculative to bother an astronomer with ;)

    BTW, what’s the tag to indent paragraphs? :)

  137. CB

    @ Joseph G:
    Heh, yeah, I was trying to picture what the different mythologies of civilizations on different sides of the moon, one with the planet constantly overhead, and the other with it never overhead, would look like.

    On VN probes: Conceptually at least they’re possible. We’re not that far from being able to make assemblers-which-can-assemble-themselves. Mostly it just hasn’t made sense yet… it makes more sense to have specialized machinery to make A, which is specialized to make B, which is specialized to produce end product C. It ends up being more efficient at industrial scales, when everything is going to be here on earth anyway.

    But it could work. One thing the probe could be looking for would be if there are any objects of suitable composition which don’t take large amounts of energy to get to. If it doesn’t see them, maybe it finishes up observations on that solar system and moves on to the next without replicating. There’s no rule that says they must replicate in every star system.

    The biggest problem to me is that indeed intelligent, self-replicating probes would not be simple at all, and no manufacturing process is defect-free, and in complicated machinery and electronics the vast majority of manufacturing defects result in a product that simply doesn’t work at all. That’s good on the one hand because it means it’s highly unlikely that your Von Neumann probes will turn into Slylandro* probes on accident. It’s bad because it means it is highly unlikely that some chains of the explore-replicate-disperse sequence will simply stop due to a failure. You could envision some kind of error-correction that tries to figure out where failures occurred and send replacement probes to cover the gaps, but that just multiplies the time constants for the expansion and thus another factor into the probability that another civilization’s probes would have arrived here already.

    * Another Star Control II reference… Slylandro probes were Von Neumann probes went wrong due to a programming error that made them prioritize breaking things down into components above all other activities.

  138. CB

    @ Joseph G:

    I still think it could be finished accelerating before it got close enough to detect from the plasma plume (again, I’m thinking about our current technology). As massive as the energy requirements are, it’s nothing compared to the emissions from a star, and there are red dwarfs that are only a few light-years away that are only visible with our best telescopes.

    You may be right.

    One thing I would like to point out, though, is that as long as we’re talking about our current technology, then any hostile alien would not have to go to nearly that much trouble. They could leisurely stroll down over to Luna, land there, broadcast a giant message on all frequencies that said “Haha! Screw you earthlings!” and start lobbing chunks of lunar regolith at us. There’d be pretty much F-all we could do.

    It’s kinda scary being stuck at the bottom of a planet’s gravity well, when you think of it like that.

    BTW, what’s the tag to indent paragraphs? :)

    It’s <blockquote>

  139. The paradox isn’t saying it’s mysterious that we can’t see them, it’s saying that given how many potential life-supporting planets there are (a number that seems to be increasing in our estimations) and the billions of years they’ve been capable of supporting life and the relatively short time (compared to stellar lifespans) it would take a technological civilization to fill the galaxy with probes (or the like), there must be some as-yet unknown reason that we haven’t encountered any such civilization. Either there’s at least one bottleneck in the equation (which is the assumption you seem to be making), or the galaxy is full of probes and there’s some reason why they’re avoiding our detection (which is not the same thing as avoiding us, another assumption you’re making). All of the reasons you give – there’s only one civilization per galaxy, there’s more than one but any others are too far away and too recent, none of them are interested in exploration, those that are interested are unable to make the journey and don’t think of building probes, none of the curious ones were able to make their probes work, their probes do work and are invisible to us – are all already-known *potential* answers to the mystery. But none of them stands out as a particularly likely explanation – it’s *possible* we’re actually the first to arrive, it’s more probable that we’re not.

    The mystery of Fermi’s Paradox is NOT that there are no logical explanations for the absence of ETI evidence. The mystery of Fermi’s Paradox is that no one knows WHICH of those explanations actually apply. The range of responses runs the gamut from Rare Earthers to nuclear or ecological pessimists to Transhumanists who think everyone inevitably retreats into virtual reality (or simulationists who think we’re already in one). It’s not an interesting question if you’ve already made up your mind as to which answer is the correct one – but the point is that nobody knows (and our inability to detect alien probes says absolutely nothing about why they might choose not to make their presence known or what that would imply). Given the available evidence, the billions of potential planetary systems, and the billions of years they could have supported life, the notion that we’re all animals being kept in a zoo is just as feasible as the argument that intelligence is a bizarre, useless fluke of evolution. As evidence from Kepler and other projects comes in, it’s looking like the incidence of planetary systems or even earth-like planets is less and less likely to be a significant limiting factor. The hope is that the Great Filters are all behind us, the fear is that the Great Silence is an indication that there’s at least one more to come.

  140. Joseph G

    @CB:
    Regarding self-replication, you’re right – so much research has gone into creating the perfect tool or machine for each component. Building a self-replicating machine may not be so much a matter of new technology as innovative engineering.
    Here’s an interesting project on the subject: reprap(dot)org/wiki/Main_Page

    Anyway, it’s a bit discouraging to think about how just plain big space is. Like you said, the outer solar system could be swarming with these things, and we’d never notice (well, not right now, anyway).
    Heh, I wonder what’d happen in the exceedingly unlikely event that two VN probes from two species met? Each one scanning the other and going “Ooh! Rich source of all the elements I need, right there!” Cue the Probe Battle Royale ;)

    One thing I would like to point out, though, is that as long as we’re talking about our current technology, then any hostile alien would not have to go to nearly that much trouble. They could leisurely stroll down over to Luna, land there, broadcast a giant message on all frequencies that said “Haha! Screw you earthlings!” and start lobbing chunks of lunar regolith at us. There’d be pretty much F-all we could do.
    It’s kinda scary being stuck at the bottom of a planet’s gravity well, when you think of it like that.

    Bwahahaha. I dunno why I find that so (darkly) funny, but you make an excellent point.
    Of course, coming that close to meeting us face-to-er…. face(?) kind of opens the door for a ragtag group of ex-military, astronauts, and one-liner-firing guys with nothing to lose to embark on a desperate mission to save the world.
    But then, perhaps the aliens like it that way. Maybe they like giving us a sporting (but small) chance :)

    PS: Damn, I have to go to work now (the job I can’t post from). I’ll be back in about 7 hours. Phooey!

  141. frankenstein monster

    I still think it could be finished accelerating before it got close enough to detect from the plasma plume (again, I’m thinking about our current technology). As massive as the energy requirements are, it’s nothing compared to the emissions from a star,

    Yes, but only if is was launched from a distance of several dozens of lightyears.
    Otherwise, it would be hard to overlook because a relativistic plasma jet radiates also in parts of the electromagnetic spectrum where the star doesn’t or does only very little. Hard gamma rays, radio waves, emission where normally absorption lines are, That all with continuously increasing doppler shift etc.

    An eerie whistle like that would cause all radio astronomers to descent on the source of the signal like a swarm of locusts.
    A faint flash of gamma rays would cause all gamma ray burst hunting satellites to turn their stare to the direction, directing other telescopes automatically to capture the afterglow.

    As for the second question: Paranoia. We can be pretty certain that any species out there is going to be concerned with self-preservation.

    Someone so paranoid to actually want to kill all his neighbors, would be probably too scared to actually attack because there is always the possibility of revenge.

    Hmm. There are tons of variables – how much lead time you have, how thick the dust is, how well the missile’s trajectory can be calculated,

    If you smack together asteroids big enough, the entire inner solar system will be filled with a fuzzy sphere of dust. the average thickness can be easily computed from the mass of the asteroids. so you can always pick asteroids big enough, or smack together more of them, to make sure that,, for example nothing above say 1% of the speed of light can make it the planet no matter from what direction.

    what it’s made of, whether it has a similar cloud of dust traveling with it to help it through obstacles like this.

    well, at that speed, the actual composition of the material is utterly irrelevant.

    And a counter cloud would not help because the probability of two grains of dust to meet and destroy themselves mutually, is orders of magnitude smaller than the probability that the grain will hit your ship.

    There is no way around it. A civilization advanced enough to be capable to bring asteroids to collide with each other ( or blow one up by some other means…)
    can defend itself against relativistic missiles at the fraction of the cost necessary to send them. The only ones you can get are the most young and/or incompetent ones. the ones, you can kill by much simpler and cheaper means, as CB pointed out.

  142. CB

    The paradox isn’t saying it’s mysterious that we can’t see them, it’s saying… there must be some as-yet unknown reason that we haven’t encountered any such civilization.

    Um, okay. “Mystery” vs “unknown reason”, “seen them” vs “encountered”… I’m not really sure what the difference is here.

    Regardless, “Paradox” implies some kind of logical contradiction between its parts. If “Given how many potential life-supporting planets etc” and “we haven’t encountered them” is a paradox, it must be because we’re taking the first part to imply that we would have encountered them, but haven’t.

    But that implication is false, and there are many plausible, known reasons why it wouldn’t work that way. So there’s no paradox.

    If we want to call it Fermi’s Banal Observation, then that’s fine with me.

    Either there’s at least one bottleneck in the equation (which is the assumption you seem to be making),

    Not me. I see no reason there has to be one or even a few parts of the equation that are particularly onerous. Many factors of modest probability multiplied together can still result in a total that makes it unsurprising to find few if any examples even among billions of star systems. I see no need to resort to a Great Filter or any filter at all to explain the Banal Observation.

    or the galaxy is full of probes and there’s some reason why they’re avoiding our detection (which is not the same thing as avoiding us, another assumption you’re making).

    Well if we’re using “avoiding our detection” to just mean “undetected by us”, then it’s what I’ve been saying is the most obvious explanation from the beginning, and the “some reason” is simply that our capabilities are still meager. So yeah, I assumed that we saying the probe “avoided” to imply something more. Oops.

    But anyway, “undetected by us, because we’ve barely been looking and our ability to do so is relatively poor” is a good explanation regardless of the existence or non-existence of any other reasons. It makes our non-observation of alien civilizations a non-mystery, because right now there’s nothing to explain. When you come home at night and don’t see your cat, it doesn’t make any sense to start speculating that he ran away, or was cat-napped, or is hiding under a bed, etc etc etc until you turn on the lights.

    The mystery of Fermi’s Paradox is that no one knows WHICH of those explanations actually apply.

    “There are many plausible explanations, and we lack sufficient data to begin to choose among them” is not even close to a paradox.

    It’s not an interesting question if you’ve already made up your mind as to which answer is the correct one – but the point is that nobody knows

    I haven’t made up my mind because there’s no basis on which to do so, and indeed no basis on which to say that there is anything which needs answering! Indeed, nobody knows. Nobody knows that there is even a problem. It’s may be interesting to hypothesize that things that might result in a certain outcome, but it’s all just a hypothetical until we know what the outcome actually was. We don’t even know that.

    (and our inability to detect alien probes says absolutely nothing about why they might choose not to make their presence known or what that would imply).

    True, and it also doesn’t say that they aren’t trying. So once again, we can hypothesize about hypothetical aliens and why they might not want to make their presence known, or how they would choose to do so if they did. But that’s all hypothetical. As far as real observations, there’s no mystery to explain.

    The hope is that the Great Filters are all behind us, the fear is that the Great Silence is an indication that there’s at least one more to come.

    LOL. The Great Silence? The tiny amount of time we’ve spent listening with our pathetically tiny ears and without even knowing what we’re listening for is ridiculously premature and arrogant to call the Great Silence. The Tiny Sufficiently Explainable On Our End Silence doesn’t indicate anything but that we’ve got a long, long way to go before we can say anything.

  143. Michael Simmons

    @Brian Davis
    Doesn’t seem to bother Venus much, with no magnetic field… so clearly
    Earth-class moons, even without magnetic fields, have no problem
    retaining habitable (liquid-water-covering) atmospheres.

    How much water does Venus have…

    http://en.wikipedia.org/wiki/Atmosphere_of_Venus

    Lighter gases, including water vapor, are continuously blown away by the solar wind

    The heavy gases remain.
    So yes a Earth class moon without a magnetic field could hold on the an atmosphere but it would loose all its water.

    RE: Rare Earth. I’ve read this via Kindle.
    We don’t know how rare it is for another body to form at the lagrange point and then migrate and impact in just the right way.

    If Venus’s slow spin is a result of a large impact similar to Earths but hitting in the opposite direction to the planet spin than this bodes well for this being a common event.
    But how many possible outcomes are there and how many led to stable habitable planet.

    We also don’t have enough information on how many of earth’s attributes are a result of this impact.
    What if plate tectonics and a planetary magnetic field (of which Venus has neither) are heavily related to having a just right impact?

    My suspicion is that the Earth is rare, but that there are other scenarios that can lead to a stable habitable planet, such as a tidally locked large moon around a gas giant.
    However its hard for me to imagine many of those scenarios leading to an environment that is as friendly to life as earth.
    I don’t see civilisations on water worlds and super earths having very active space programs.

  144. Electro

    @ Brian Davis#121

    “during these “eclipse seasons”, you’d get more than a 10% decrease in insolation on one hemisphere relative to the other. That could result in a slight variation in “seasonality” on top of the more normal mechanisms.”

    Thank you for the explanation, Brian.

    Since you are clearly more conversant with these mechanics than I am, I have to wonder, if all three were in an ecliptic plane, would these daily eclipses not render this moon an ice ball?

  145. Electro

    Could someone please point me to the source of the quote which is para-phrased by me to be:

    Out of all the infinitely possible Universes, there maybe only one with exactly the right physical laws to support life as we know it. We live in that one.

  146. Buzz Mega

    A million. Plugging that into Drake, the chance of a civilization coexisting with us is 1/4,500 (age of the solar system in millions of years). Then parking those guys near enough to chat (even over long time scales) would reduce transactional opportunities to sub-microscopic.

    B’ b’ but UFO’s are real. They have to be. Otherwise my life is a sham.

  147. frankenstein monster

    So yes a Earth class moon without a magnetic field could hold on the an atmosphere but it would loose all its water.

    Actually, no. venus lost all its hydrogen because of the runaway greenhouse effect.
    Oceans evaporated, the water vapor got high into the atmosphere, dissociated, and hydrogen was lost to space.

    Under normal circumstances the stratosphere is bone-dry, thus water loss speed is even less than overall atmosphere loss speed.

    Which would be high , to be sure. Venus has a thick atmosphere, because the high surface temperature has driven away all volatiles that would normally be chemically bound in the rocks.

    A normal, temperate, earth sized world would have hard time to keep a thick atmosphere. But if it were a bit larger, more volcanism, deeper gravity well, I think it would work.

  148. Gonçalo Aguiar

    “Not to give too much away, but one of the main characters (sort of their “Galileo”) discovers that the moon they live on is moving closer to its planet due to tidal forces, and will actually break apart on a geologically tiny time scale (a millenia or so at most).”

    I’ve read somewhere that a Jupiter asteroid/comet Super Hero can be both a blessing and a curse, for the inward planets. It’s gravity can attract asteroids to himself, yes. But it also can slingshot them to the right delta-V so they can enter the inward rocky planets in the habitable zone. A proof of that is how NASA send Messenger to Mercury, they used Venus gravity assist a couple of times…

  149. JR

    @Scruffy #67

    Those conditions you described are simply the conditions under which life evolved on our planet. Obviously, if they were different, life in this exact form wouldn’t be possible.

    But that doesn’t mean they’re the only conditions under which advanced life can evolve.

    Also, orbital mechanics 101.

  150. Joseph G

    @ 148 Frankenstein’s monster:
    Whew. Well, as disappointed as I am to be denied my apocalypse scenario, I do hope you’re right :)

  151. Mark

    Hey Phil,

    I just wanted to point out that although Kepler has found just a limited number of “Earth-Sized” transits, it’s very likely there are many Earth-sized planets that are undetectable as they get lost in the noise of the light curves (let alone the ones we can’t detect using the transit method as you mentioned).

    I say that because I’ve been participating in planet hunters and after examining thousands of stars it turns out Earth-sized planets are still really difficult to detect, even for Kepler.

    So the amount of Earth-sized planets is likely much higher even in this little region of space Kepler is examining.

    I may e-mail this comment to you if you don’t happen to see it.

  152. Scott P.

    “A million. Plugging that into Drake, the chance of a civilization coexisting with us is 1/4,500 (age of the solar system in millions of years).”

    How do you “plug that into Drake”? Half the terms in the equation we can’t even provide a guesstimate for.

  153. wye

    Along the lines of this example: 1/10 = x/100, and cross-multiplying for 10x=100, with the answer being x=10…

    I used the value of 250 billion stars in the Milky Way (orthodox estimates are between 100 B and 400 B, I believe).

    If there are five (5) approx. earth-sized planets in the Habitable Zone of their stars, out of 156,000 stars surveyed by Kepler, then the extrapolation to “approx. earth sized planets in the HZ of their star among 250 B stars in the Milky Way” is:

    5/156,000 = x/250,000,000,000

    x= more than 8 million approx. earth sized planets in the HZ of their star among 250 B stars in the Milky Way

    This of course in no way accounts for planets orbiting their star on a plane other than one in which they transit their star relative to Kepler. Kepler can’t see planets that don’t transit their star relative to Kepler.

    So the number 8 million is probably just a fraction of the true number. (I realize that earth-sized does not necessarily mean terrestrial.)

    Is my basic math OK? I am not an advanced math person, but I am a science person.

    I did not understand Phil’s statement: “70 million Earth-size planets, and a million in the habitable zone of their stars. A frakking million. In our galaxy alone.” I took this to mean a million earth sized planets in the habitable zone of their stars. I did the math myself and came up with 8 million, not 1 million. Phil didn’t say what number he used for stars in the Milky Way, but I don’t think it matters unless he used a very unorthodox number like 31B.

    Kepler has pulled back the veil, it is a momentous day.

  154. Joseph G

    @161 Mark: No offense, but others have said essentially the same thing (about the transit method, anyway).
    As far as the planet-hunter thing, you’re right – I’ve tried it (the Zoouniverse thing) and I have no idea HOW they manage to find something so small in so much noise!

    Wye: Kepler has pulled back the veil, it is a momentous day.
    You said it! :)

  155. Mark

    @165 Joseph
    No offense taken as I already acknowledged the transit method being mentioned. My main point was about earth sized planets easily being lost in the noise to Kepler (which Phil does not mention in his article). I thought I made that clear. Hrmmm. I apologize if it wasn’t.

  156. So … which star was the one with the Earth-sized planet in the habitable zone?

    (And don’t you DARE say “Sol.” I’m lookin’ at YOU, laserbreath!)

  157. 1. When are talking about Earth-like planets (with such star/planet diameters and orbital radii), Kepler sees a transiting exoplanet out of every ~350 systems. The numbers for other orbits are different, but You can multiply the numbers at least by 100 or even by 1000 when You estimate the minimal number of planets in the galaxy. (Supposing that the axes of the orbits aren’t aligned in some ways, which cannot be ruled out and hard to prove).

    2. Afaik Kepler team only released the quarter 2 date, that is summer of 2009, only three months of observation. They possess now 5 more datasets.

    3. Amateurs at planethunters.org have found 130 exoplanets in Kepler’s previous datasets, 83 of them are practically verified by the Kepler team. This is great.

  158. vanDivX

    Kepler discoveries didn’t surprise me at all, just confirmed what I’ve been thinking all along – that our own Solar system is no freak (if Sun was among stars monitored by Kepler, how many planets would it detect if it happened to be correctly aligned? Certainly not all of them. and most would escape the observation window due to much longer transit time than the 3 years which Kepler is supposed to monitor for, never mind their proper alignment in just the right plane.

    The biggest obstacle I see for possible contact with ETs are the immense distances separating possible intelligent life occurrences. I don’t believe in FTL travel or some theorized shenigans in the form of some wormholes or space warping and such like. That we don’t detect any ET signals and haven’t been visited by any is what is to be expected. And even supposing some dead probe like our Pioneer or Voyager but built and sent along by ETs came to whiz through our system (which in itself would be like hitting some cosmic jackpot because more likely it would miss our system most likely), what are the chances of us even noticing such event? Those probes are like half tone fridge misiles with solar panels and dead as doornails. I don’t think we would notice them unless they hit us square on… I don’t believe in some star trek style ships, never mind even those wouldn’t be big enough to be guaranteed detection even if we hit that cosmic jackpot and they came rocketing through our inner solar system.

    Also I completely discount any ideas of ETs coming as enemies or not venturing out in the first place if they could because they wouldn’t be interested in other civilizations or that they would have ventured and seen so many that they would be bored of seeing any more… those people thinking along these line should cut back on their scifi reading and dreaming.

  159. phil harvey

    Larian, the range of RF transmissions will be infinite and not limited to multiple AUs and LYs as a function of terrestrial transmit capability!! I really don’t know where you got this list, but it makes no sense.

    The real ‘range’ of any transmission; ie the range at which a signal could be detected, will be a function of the receiver sensitivity (determined by noise temperature of the receiver subsystem) and antenna gain (G/T) of the receiving station. Also, receiver antenna gain may be enhanced through use of synthetic aperture very long baseline interferometry.

    Consequently, ‘range’ will be determined by the type of technology available to any alien race, and thus not wholly a function of terrestrial antenna size and transmit power.

  160. phil harvey

    Wye, you correctly indicate that Kepler can only assess those planets that actually transit in Kepler’s line of sight. I understand that statistical analysis has so far lead to the estimate of between 1.7 to 2.7 % of sun-like stars alone may have Earth like plantes in the habitable zone. If we then assume only 100 x10^9 stars in the Milky Way, then this leads to a figure of at least 2 billion Earth like planets in the habitable zones of 1.7% of G2 stars in the Galaxy.

    Given the immense distances and relative evolutionary timescales, it may not be surprising that we have not heard from any intelligent race, or them of detecting us for that matter. For instance, if we consider that the vast majority of time on Earth had only bacterial life, then uninhabitable glaciation periods, global extinctions and then advanced, but dumn animals (eg dynosaurs), then perhaps not surprising at all that we have not yet made contact with extraterrestrials. Kinda worrying though!

  161. phil harvey

    Electro, your paraphrased script of ~: ‘ Out of all the infinitely possible Universes, there maybe only one with exactly the right physical laws to support life as we know it. We live in that one’ has been quoted in a number of sources. try the book by Paul Davies ‘The Goldilocks Enigma – Why is the Universe Just Right for Life?’

  162. phil harvey

    vanDIVX….I admire your ‘rationality’ and scientific thinking. However, without the dream of the sci-fi community (and that includes scientists!!) then the stretch of imagination that could lead to descoveries would not occur. That would get us no where.

    Indeed, I believe the dream of space travel in the early 20th century, which seemed so impossible at the time, eventually became reality. If we take the clock back further, it was an astronomer who argued that faster than horse-speed carriages would result in passenger suffocation!!! He was certainly no dreamer, and incorrectly extrapolated his limited understanding of physics.

    With regard to wormholes, these are indeed a strong theoretical possibility (albeit at the sub-microscopic level). The energies to expand to large space may not be possible….but that is where dreams can help trigger the imagination to make it happen; who knows.

    Warping space? Why not? The Cosmos may well exist as a multiverse (as per current theories) with island universes existing in a ‘soup’ of non space/time. The fabric of space-time is therefore peculiar to each and every universe. With sufficient energy why cannot this fabric be disrupted? If it could be, then travel between points in space need not be constrained to light speed restricted by the space-time continuum. Sounds totally sci-fi, but I nevertheless don’t consider this ‘sci-fantasy’.

    Being ‘rational’ is all well and good, but i don’t believe it wise to assume ‘rationality’ when the human race is limited in its understanding of physics; especially when quantum mechanics and gravity have yet to be reconciled and 78% of the universe we observe is nowhere yet understood (ie the nature of dark matter and dark energy)!

    Who knows what has yet to be descovered that could lead to ‘faster-than-light’ travel.

    (and yes, there is the argument that there may be many earths and civilizations out there that are also many mellenia ahead of us technologically …..and if so…and if physics can allow faster that light travel….so where the bloody hell is everyone??…a strong, but sad, argument in your favour if they all exist I guess!….does the UFO community have anything to say I wonder??)

  163. phil harvey

    Marian. The periodic table of elements appears universal. We see this in spectra of distant light sources. The type and nature of chemical reactions can therefore be expected to be universal.

    If the basic laws of physics can alter in other universes within a possible multi-verse, then who knows; elements and chemical reactions could then work differently, and thus may not create anything like life as we know it.

  164. Bill.Finlan

    Let’s not forget that this tally only includes potential planets whose orbits are on an exact plane between our view and the star being orbited. If the orbit of a planet in any of the star systems being viewed is off of our plane of observation by only a couple of degrees, we won’t see a dip in the light strength from the star. For instance, if the orbit of the potential planet is at a 45degree angle relative to the plane of our view of the star, we won’t see it, because it doesn’t cross the face of the star from our vantage point.

    In other words, we must assume that we are only observing a small fraction of the potential planets out there with this method.

  165. Menace

    Dude I am soooo FREAKEN excited about this! So why don’t we just build a BIG A** telescope and take it up out of space and then view other planets outside of our solar system!? But got to make sure it can view very close up on the planets like “Google” map. It’ll take a WHOLE lot of money for it to happen but if “scientists” or “atronomers” or whatever they’re called are really dedicated to a whole new discovery in our stupid f***** up little world, then they would risk everything for this new sh**!!! I mean seriously though, I want to see other life form creatures or whatever from other planets with higher tech or lower tech or savages creatures and learn something new for once! Don’t ya’ll AGREE??? I mean there are going to be troubles and all because it can be very dangerous discovering a life like planet and encounter other life form creature that can be smarter and very high-tech than our technology. For example; the movie “Predators vs Aliens”, sheeze imagine being in the middle of a war, or a galatic/space war between extinction of a certain race or species! Just like the game “Halo”.

  166. narner

    To all the posters that say a solar system has to be just like ours to support complex life: That is only theory at this point and based on the only example we have it is not a fact in anyway. Get some imagination.

    To all the people that say we should fix everything on earth before we explore out side of it.: Is your house perfectly tidy every time you leave it? Sure it would be nice to have every thing in order first but we all know that getting everything in order never lasts long and so far historically has involved some kind of dictatorship. That isn’t good either. Nothing will ever get done if we wait till every thing is fixed on earth. Last our population is already too big. I would rather it was controlled by people moving to mars and beyond than with wars , famine and disease. Space exploration really is our only hope.

    Last. gas giant planet is in a habitable zone and has a appropriately sized earth like moon. Would the magnetic field of the gas giant protect the moon from solar radiation. Does Saturn Protect titan in this way?

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