back to article Looking for a home off-world? Take your pick: Astroboffins estimate there are nearly 6bn Earth-likes in the Milky Way

There may be more than five billion Earth-like planets that are rocky, potentially habitable and orbit main-sequence stars like our Sun scattered across the Milky Way, according to the latest estimates. Astronomers from The University of British Columbia (UBC), Canada, arrived at that figure by combing through old data …

  1. Mike 137 Silver badge

    "Getting to them is, however, quite another kettle of fish"

    Actually, getting to them will probably be the lesser of your worries unless you just want to commit suicide expensively. Ecosystems are complicated, and finding a niche is hard even on Earth where all life has fundamentally co-evolved. Hard in the sense that there are masses of failures, both at the species and the individual level. This will be all the more the case for an entirely alien species (us) on a distant planet with its own evolutionary history.

    Even if the lovely fantasy of a perfect human-supporting habitat devoid of competitors were to be found, staying a live long enough to take advantage of it would be a serious challenge as adaptation takes generations to accomplish. Either way, we should expect more than half of the human settlers to die before they reproduce - probably vastly more than half, so we'd have to send huge populations of settlers with a known high probability of snuffing it as part of the deal.

    Only on Star Trek are small human communities able to settle stably on alien planets, and that's just because the writers ignore the science.

    1. Blackjack Silver badge

      Re: "Getting to them is, however, quite another kettle of fish"

      Before humanity knows we can life off world we should see if we can life on our moon that's quite close in case of a screw up.

      1. logicalextreme Bronze badge

        Re: "Getting to them is, however, quite another kettle of fish"

        You're saying that we shouldn't aim for the stars just yet. That's prudent advice, because they can get pretty warm and the houseplants might die if we tried to live on one.

    2. logicalextreme Bronze badge

      Re: "Getting to them is, however, quite another kettle of fish"

      So you're saying if we ignore science then we can do it, right?

      If that's the case, the Government seem like the ones in the best position to get us there.

      1. amanfromMars 1 Silver badge

        Re: "Getting to them is, however, quite another kettle of fish"

        So you're saying if we ignore science then we can do it, right?

        If that's the case, the Government seem like the ones in the best position to get us there. .... logicalextreme

        That's an extremely perverse and subversive fuzzy lazy logic exercised there, amigo, which requires more immediate action from actors, both state and non-state, sooner rather than later because of the true nature on Earth of both elected and fascist governments alike for they be both parasitic and inevitably deadly self-destructive, hence the rush needed to get anything planned long term done ‽ .

        “You cannot legislate the poor into prosperity, by legislating the wealthy out of prosperity. What one person receives for not working for, another person must work for without receiving.

        The government cannot give anybody anything that the government does not first take from someone else.

        When half of the people get the idea they do not have to work, because the other half is going to take care of them, and when the other half gets the idea that it does no good to work, because someone else is going to get what they work for, that my friends is the beginning of the end of any nation.”

        And they just can't help themselves from taking and using future generations wealth to pay for present situations which are predicated upon past gross practices.

        1. logicalextreme Bronze badge

          Re: "Getting to them is, however, quite another kettle of fish"

          My humour is nothing if not lazy.

        2. Cliff Thorburn

          Re: "Getting to them is, however, quite another kettle of fish"

          And they just can't help themselves from taking and using future generations wealth to pay for present situations which are predicated upon past gross practices.

          Amen to that AMFM, in addition they certainly cant help foray into veritable Vatican exploits of exponential learnings lurking in live operational virtual environments, invoking torture and torment and taking innocent individuals on battalion spread betting human fox hunts for estranged entertainment.

          Just as well we dont have the Church Comittee in blighty to hold those ultimately accountable with mass MK Ultra experiences and experimentation so blatantly wielded is it not?

          1. amanfromMars 1 Silver badge

            Re: "Getting to them is, however, quite another kettle of fish"

            Quite so, CT. But to imagine it not an embarrassment to have a Church Comittee in blighty to hold those ultimately accountable with mass MK Ultra experiences and experimentation so blatantly wielded tangling with a Vatican type operation, is surely evidence of a lack of necessary intelligence in both required in order to proceed.

            The Vatican appears presently to be somewhat currently cuckolded rather than reigning rampant in the Realm ......... and that is surely as a result of deficient top down leadership/Papal Impotence/Immaculate Virgin See Blindness.

            1. Anonymous Coward
              Anonymous Coward

              Re: "Getting to... ...fish"

              ...must contains sails

              (-;

    3. teknopaul Silver badge

      Re: "Getting to them is, however, quite another kettle of fish"

      No rules says you cant live on a planet if you have to wear a suit outside.

      I personally am ill equiped for a sunny day or a winter's night on this planet without some protection against the natural environment.

      I suspect we will make the moon and mars habitable in some ways, as we make this planet unbearable without protection outside.

  2. Spherical Cow Bronze badge

    The real Goldilocks zone

    At last, an exoplanet hunter who is steering clear of those myriad pesky red dwarves with their tight planetary orbits and harsh tidal locking.

    1. logicalextreme Bronze badge

      Re: The real Goldilocks zone

      Your comment is strangely arousing.

  3. batfink Silver badge

    Nice science but...

    I should point out that both Venus and Mars would be considered to be in the "habitable zone" around our own star.

    TBF the authors probably had a bit more detail in the original publication, such as an actual definition of "earth-like", which I suspect was along the lines of "rocky planet with the possibility of liquid water". Fun to think about though.

    1. Mage Silver badge

      Re: Venus and Mars

      Venus certainly isn't. Antarctica, Sahara and our oceans are far more habitable than Mars, which realistically is no more habitable than the Moon. Basically a space station with gravity.

      1. logicalextreme Bronze badge

        Re: Venus and Mars

        I think it's been posited that we could potentially live in a particular part of Venus's atmosphere, in some sort of ridiculously high treehouses, if we were really bored and due to a budgeting error suddenly had an infinity of money to spend.

        Down nearer the surface…well, I seem to recall that the Venera probes that managed to land were all fairly quickly crushed by the density of the atmosphere.

        1. Jellied Eel Silver badge

          Re: Venus and Mars

          I think it's been posited that we could potentially live in a particular part of Venus's atmosphere, in some sort of ridiculously high treehouses, if we were really bored and due to a budgeting error suddenly had an infinity of money to spend.

          But that's old-fashioned capitalism and economic thinking. Central banks already discovered we have infinite money, just a finite amount of practical things to spend it on. In a post-scarcity future, we'd have a near infinite amount of resources, and different mediums of exchange. So instead of promising to pay the bearer of £1 err.. £1, it could be lifting 1lb of <something> from surface to space. Which would still give banks something to gamble on based on local gravity rates.

          Or, given the number of planets just in the Milky Way, everyone could be offered their own planet in exchange for their labor. Delivery not included, refer to travel & subsisdence schedule and royalty table to understand your earn-out.

          But it's fun stuff that SF writers have addressed, amongst others. Like what has value in an interplanetary or interstellar economy, and what would be the exchange rate? Things that are currently scarce wouldn't be. Peter F Hamilton's Fallen Dragon has some interesting themes of value in a post-scarcity and post-FTL future.

          1. tfb Silver badge
            Boffin

            Re: Venus and Mars

            In a post-FTL future nothing has value because the resulting causality-violation means you can fuck with the past so games of chance, like the stock market, stop working.

            (I know, you meant special magic unphysical sci-fi FTL which conveniently lets you do the going-to-the-stars thing without the inconvenient build-a-timemachine thing which is an immediate consequence of it and is what you'd really want to to (if you don't get to work sending information about markets back in time so you can win the stock market and take over the world someone else will, and you'll be their slave (literally)). I read books like that too, but you have to ignore any predictions they make because of huge holes like this.)

            1. Jellied Eel Silver badge

              Re: Past & Futures markets!

              I read books like that too, but you have to ignore any predictions they make because of huge holes like this.

              But.. but.. I guess there's a variation on Fermi's Paradox. So if travelling to the past were possible, someone would already have done it. Unless there were time cops, who'd prevent tampering with causality. I suspect Joanna Lumley of being one. Or someone may be transmitting tachyons with vital information to us so our future selves can save our present ones. Or it's proof of branching universes, and it's been done, yet we remain stubbornly in our original time line.

              Or it's been done. But our future selves decided to redefine both Imperial and Metric units as legacy values, set sail for where the Earth was, and missed.

              But OK, so FTL travel is something of a dream to get around the vastness of space. But to an extent, the idea that we couldn't exceed the speed of light is also SF.. albeit the 'S' is rather stacked against it. But who knows, some day, Elon may create the infinite improbability drive that just keeps accelerating.

              Either way, the stock markets get more interesting with commodity futures.. But there's also historical precedent for this, ie trade ships getting faster, then communications aiding price discovery. I think it'd still leave Earth in an interesting position. So assuming colonies become self-sufficient, they wouldn't need Earth, but Earth would need their resources.. But why trade? Or what to trade? I think that would leave a market for luxuries, so genuine Earth champagne, or the original Mona Lisa, but it's fun stuff to think about.

              1. tfb Silver badge
                Boffin

                Re: Past & Futures markets!

                Yes those stories – the ones with time police or branching universes or ... – those are the interesting ones, the ones which take the trouble to explain away why we can't just bargain FTL communication into sending information into our own past with technology we could, in principle, build now. The ones that just drop FTL travel in to make a better space opera without addressing the consequences can be fun to read but they are just space operas. I'm not against them – I've read many – I just think they're not plausible.

      2. JDX Gold badge

        Re: Venus and Mars

        Mars has atmosphere of sorts, that can be processed. It even has water. I don't think it can be compared to the moon really.

        1. Charlie Clark Silver badge

          Re: Venus and Mars

          Gravity is so low on Mars as to make the comparison reasonable: human life on Mars is nothing but a fantasy.

          1. amanfromMars 1 Silver badge

            Re: Venus and Mars

            How about, Charlie Clark, Martian Life on Earth ? What are the chances? Be honest now?

            Another fantasy for Fantastic Stealth?

          2. Anonymous Coward
            Anonymous Coward

            Re: Venus and Mars

            Gravity is so low on Mars as to make the comparison reasonable:

            38% of Earth, compared to the Moon's 16% ? Not that close.

            1. Charlie Clark Silver badge

              Re: Venus and Mars

              Not the same but comparable: low gravity is one of the reasons for little atmosphere, which does more than give us something to breathe: space is a hostile environment!

      3. eldel

        Re: Venus and Mars

        Neither Venus or Mars are 'habitable' you are correct. They both, however, lie in the habitable zone of our solar system. Which is, AIUI, defined as they get enough solar radiation to allow liquid water to exist on the planetary surface.

        Their human habitability shows just how little that 'habitable zone' designation means. It's a lower bound - nothing more.

    2. Doctor Syntax Silver badge

      Re: Nice science but...

      "rocky planet with the possibility of liquid water"

      Maybe add "has a magnetic field" to the list of requirements.

  4. Mage Silver badge
    Alien

    In theory

    Let's not repeat the European exploitation of Americas, or Arabs in Africa moving south. Ethically would it be right to settle without an invite?

    It's likely anywhere able to really support life would be teaming with life of its own. Likely the existing plants and animals would only be good for fats, sugars/carbohydrates and maybe protein. They'd likely lack suitable vitamins and amino acids. Even here not all plants or animals can sustain humans, you'd likely die just living on rabbit. Animals here also have differing needs of vitamins, amino acids and things that are toxic.

    However, as C.S. Lewis remarked, perhaps the interstellar distances are a quarantine system. We have no evidence that any sort of interstellar travel other than a mostly coasting Generation ship is possible. We need to sort out our own problems here instead of exporting people and their associated shortcomings.

    Interesting science.

    1. Teiwaz Silver badge

      Re: In theory

      We need to sort out our own problems here instead of exporting people and their associated shortcomings.

      And if it turns out most of our problems are due to being cooped up on one increasingly overcrowded rock, with some trying to carve out their own niche, others trying to climb to the top of the heap no matter whose face they step on?

      1. tfb Silver badge
        Alien

        Re: In theory

        Then we're not going to make it. Because despite the dreams of various fantasists this is almost certainly all we will ever have.

        We probably will make it as a species until the next big meteorite strike: even quite bad human-driven events (flat-out nuclear war) probably won't kill everyone, and the worst plausible climate change leaves hundreds of millions alive. We almost certainly won't make it as a civilisation.

      2. Charlie Clark Silver badge

        Re: In theory

        And if it turns out most of our problems are due to being cooped up on one increasingly overcrowded rock

        Then we're likey to have the same problem on any other rock.

  5. karlkarl Silver badge

    One day our ancient radio waves will reach them! ;)

    1. Mage Silver badge
      Facepalm

      re: radio waves will reach them!

      If you do the sums, you'll see that the likelihood of our radio waves being detectable even at the nearest star is slim to zero. They might detect our oxygen, water, CO2, nitrogen and industrial pollution via spectroscopic analysis. SETI using radio is pointless unless Aliens arrive at the edge of the Solar system.

  6. JDX Gold badge

    Pretty cool science

    I remember when they confirmed the first exoplanet (90s) which means I remember the time when it was unknown if planets like earth were very rare or even unique. I'm not even that old... now we not only take their existance for granted, we know they are pretty commonplace.

    How drastically this particular field has evolved in only 20ish years is pretty amazing, many of you have children who are older, when one considers what a huge impact it has on our view of the universe.

    1. Ogi
      Thumb Up

      Re: Pretty cool science

      Me too! I remember the episode of Horizon from 1996 that dealt with it, "Planet hunters". I still have a digitised copy which I occasionally watch for nostalgic reasons, and it is amazing to see how far we have come.

      At the time of that episode, they still had no idea how many planets there were out there, most stars they investigated seemed to have none. Finding the first ones (AFAIR, it was orbiting a pulsar), was a serious event, even though they had no hope of harbouring life.

      Now it seems almost every star has some kind of exoplanet, we have so many we need machines to keep track of them, and keep finding more and more planets in existing data.

    2. tfb Silver badge
      Boffin

      Re: Pretty cool science

      I've just been looking at my copy of Misner, Thorne & Wheeler. There is a spooky footnote in the introduction which must have been added late in the publication process, saying 'As of April 1973, there are significant indications that Cygnus X-1 and other compact x-ray sources may be black holes.': when they wrote the book there were no known black holes, and I don't think everyone even thought they were physically plausible. I bought it in 1985, Hawking conceded his bet that Cygnus X-1 was not a black hole in 1990, and Thorne Weiss & Barish won the Nobel prize in 2017 for the direct detection of gravitational waves, from BH-BH mergers among other things.

      I've said this before but we're living through a golden age for astronomy and astrophysics. All the theoretical physicists who mourn the lack of progress in fundamental physics are just not paying attention: something that some astronomer observes or has observed is going to be the key which leads to the next big revolution in fundamental physics. They've already observed things which mean that the form of the equations of GR is now different than the one in MTW (there's no index entry for 'cosmological constant' in that book that I can see).

  7. amanfromMars 1 Silver badge

    A Deep Dark Cloistered Secret ???????

    Getting to them is, however, quite another kettle of fish

    It helps immensely to be au fait in the Way of Transubstantiation.

    If in doubt, just ask the truly devout in brothers and sisterhoods.

  8. G R Goslin

    Ah, but

    Ah, but how many of them have the pubs open on Sunday? Importance is in the detail.

    1. Francis Boyle Silver badge

      I believe

      there's a planet where drinking water is permitted only on the 11th day of the week. The rest of the time you have to stay sober by restricting your liquid intake to alcohol.

  9. johnnyblaze

    The universe, and galaxies like our Milky Way are literally teaming with life, Even if only 1% of what they imply actually has sentient life, that's an awful lot still. We just havent found it yet, because let's be honest, humanity is probably the equivilant of a neanderthal in comparison to many other civilisations.

    1. Doctor Syntax Silver badge

      "literally teaming"

      Oops!

      As for literally teeming, would the literature be science fiction?

    2. Charlie Clark Silver badge

      Question your assumptions and define your terms. Tiny changes in a planet's geology and chemistry would have profound implications of the development of life and thus ideas like sentience. Even taking the temporal dimension into account, our solar system is relatively young, this does not imply that things could have started elsewhere much earlier while taking a similar enough path, especially if some of the universal constants turn out to be slightly less than constant in spacetime.

      That said, I'm sure the universe will continue to surprise us.

  10. Version 1.0 Silver badge
    Angel

    Call and ask for help

    Maybe if a world that was never hit by an asteroid hears us then they will send a big spaceship to pick us up, probably piloted by a T-Rex (not Marc Bolan). Be careful though, it might only accept travelers who are chocolate coated to make a nice snack when they arrive on the new Earth-like world.

    1. ThatOne Silver badge

      Re: Call and ask for help

      "Never hit by an asteroid" doesn't necessarily mean there were no mass extinctions and reshuffling of the biosphere: Volcanoes can do that too, and you can't avoid volcanism (because liquid core, because magnetic field, without which your atmosphere tends to take a hike making life impossible. See Mars).

      Also climate is apparently quite unstable on the (geological) long run (ice ages, hot periods, etc.), so life is probably going to successively try several, wildly different solutions to the environmental challenges present at any given time.

      My point is, we have no chance to imagine what we might find on those far-away "habitable" planets. I mean, we're still baffled by the things we discover living on our own planet...

      1. tfb Silver badge

        Re: Call and ask for help

        That's a good point. Is today's climate hospitable to dinosaurs? If it's not, and if the dinosaur-killing event didn't have really long-term (millions of years: obviously it had large shorter-term effects)) effects on the climate then they wouldn't be here now anyway.

        1. ThatOne Silver badge

          Re: Call and ask for help

          > they wouldn't be here now anyway

          I'm no paleontologist but from what I heard, some of the strange creatures which have existed in the past were only possible due to the increased temperature and oxygen levels of that time. Indeed, huge cold-blooded lizard-type creatures would obviously only be possible in very hot climates, and animals which breathe through the skin, like insects, can only grow as big as the current oxygen levels allow. And so on.

          Given it's our own planet which has gone over time through all those very different phases (and certainly hasn't finished doing so yet!), it is clear that "Goldilocks" planets out there will display a astounding variety of ever-changing situations, climates, and thus ecosystems.

          1. Charlie Clark Silver badge
            Alien

            Re: Call and ask for help

            Not all reptiles are cold-blooded. Hence, the fossils in Antartica from the time before it was cut off from the other continents.

            But any fule no that fossils are fakes anyway planted by our lizard overlords!

            1. ThatOne Silver badge
              Happy

              Re: Call and ask for help

              > Not all reptiles are cold-blooded

              Sure, but a big part is, and my point was just about the environment limiting what life type you might encounter. For instance woolly mammoths would have a hard time in the present times at temperate latitudes (abundant sweat+wool causing them to shrink until they eventually become purse pets for rich ladies).

  11. Rustbucket

    Own Goal

    If this goes ahead, Trump and his merry band of GOP nutters will promptly be thrown off the social networks like Facebook and Twitter because those companies couldn't afford to be exposed to litigation for their defamatory and racist comments.

    1. Toni the terrible

      Re: Own Goal

      huh?

      1. KarMann Bronze badge
  12. Ugotta B. Kiddingme Silver badge
    Alien

    well, if we ever DO make it to one of those worlds...

    ... be sure to first check their library and verify they don't have a book called "To Serve Man."

  13. Twanky Bronze badge
    Boffin

    Science

    G-type stars are more likely than other types to host planets capable of supporting life. They are pretty small and have a similar mass close to our Sun.

    What new science is this? When they're further away from our sun their mass becomes dissimilar?

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