back to article Billions of potentially populated planets in the galaxy

There are billions of habitable planets in the Milky Way where aliens could be having their tea right now, according to a new six-year study. "Our results show that planets orbiting around stars are more the rule than the exception. In a typical solar system approximately four planets have their orbits in the terrestrial zone …


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  1. hi_robb

    Let me

    Just welcome our new tea eating alien overlords.


    1. Graham Marsden


      "You'll have had your tea, then?"

  2. Mikel
    Thumb Up

    Don't forget exomoons

    Add in the moons around planets in the habitable zone and the number of stars with no habitable bodies should be nearly zero.

  3. maccy

    ok, so where are they?

    maybe they're all too busy playing "Angry Gnarfgles"

    1. Mad Chaz

      Just maybe

      They are mostly all looking up at the stars and wondering "are we alone?"

      Remember, our own radio signals aren't even all that far out yet. That is, if they can even be heard at all on that kind of scale.

      1. King Jack

        They went digital eons ago, so all our analog transmissions file by as noise.

    2. Mips

      "Angry Gnarfgles"

      Basically you think the light is on but no one is home. Bit like Earth then.

  4. Beau

    ET. Phone home.

    Your number is:- 00587-68592-22788-44584-03565-33151-65538-05479-86110-12988-65221

    1. Charlie van Becelaere


      that's a purloined Windows activation code!

      1. Paul 129

        Alien phone numbers and Windows

        That explains a lot!

      2. dssf

        Nahh, it is not a phone number...

        It is a set of jump coordinates, converted from another song Kara Thrace's father taught her as a child.

        It probably can be reduced to the equivalent of NGC-1252 Tuvan Throat Singers' tonals in an acoustic conduit.

        On a Galactica threat/note, I really wish that we are just the descendants of interbreeding, and that our distant relatives are out there, looking for us after hearing of a band of refugees seeking a new home. Wouldn't it be something to have distant cousins "find us". They might come to regret it, though -- if they exist at all.

        I'd prefer to believe that if comets brought water to the Earth, then it can and ought to have happened for other worlds. Even if only 1,000 other worlds, even if they are too far for *us* to detect yet. Unfortunately, we may not as a species/world find other advanced life until 5 or 10 more lifetimes from now, assuming they cannot cloak themselves to decieive us into looking elsewhere, assumng they've been approached by others and learned to remain anonymous, hehehe.

        To me, it would be sad if we are all there is of sentient life forms. It would be a cosmic waste of the universe's sheer size to have this vast support system of gravity, wells, energy, and so forth, a huge cosmic show, just for *us*. Kinda depressing. I hope there's more, a LOT more life (intelligent, sentient, comparable) out there -- even if we don't get to find out.

    2. Dan 10


      If you are a carbon-based xenomorph, press 9823749827549384643897

      If you are a....

  5. Tom 7 Silver badge

    I'll be off then

    oh hang on the forbidden fruit planet is patented...

    1. Thomas 4

      Just think

      Out there, in the vastness of the cosmos, there could be completely new and exciting forms of patent trolling and fanboi flame wars.....

  6. Anonymous Coward
    Anonymous Coward

    Drake equation

    “This means, statistically, every star in the galaxy should have at least one planet, and probably more,”

    "Statistically, the research team extrapolates that [...] two-thirds have an Earth 2.0."

    So now we know that "Fp" is about 1 and "Ne" is 2/3. How does this affect current estimates?

    1. Anonymous Coward
      Anonymous Coward

      It doesn't

      See maccys slightly mis quoted quote 'so where is everyone?'

      Several scenarios

      1) They never made it past our equivalent of WW3 or some other self made disaster

      2) They have made it past that stage and are far advanced. Possibly observing. Possibly not

      3) Some kind of natural disaster killed them all

      4)Their radio hasn't reached us yet and are most likely 'dark' to our listening abilities by now. (We can only measure that which we know how to measure)

      5) Space. It's big!

      1. Anonymous Coward
        Anonymous Coward

        Obligatory space quote....

        "....I mean really big. You wouldn't believe how big it really is. You may think it's a long way...."

      2. Nigel 11

        Radio broadcast obsolete

        6. Radio of a type capable of detection across interstellar distances becomes obsolete within a couple of centuries of its invention.

        We know that's true because it's happening all around us. Analogue broadcasting (with easy-to-detect carrier frequencies) is being turned off. Digital signals are far more efficient, meaning far harder to detect at interstellar distances. Also for how long will radio broadcasting exist at all? The Internet is starting to replace broadcast in developed countries.

        I doubt that 22nd-century Earth will be radio-detectable from tens of light-years out, let alone hundreds or thousands. (I'm assuming technological progress continues ... but it's also true if we blow ourselves up).

        1. Anonymous Coward
          Anonymous Coward

          That's what I meant when I said they had gone 'dark'

  7. Alan Firminger

    "But planets that are either very far or very close to their star can be missed by this technique"

    And every star where the axis of the planetary orbits is not perpendicular to our line of sight, which is most of them, are missed by transit observations because nothing transits.

    1. Mikel

      not perpendicular

      @Alan - Fortunately this fraction can be estimated and extrapolated. And we still have star wobble for the others.

    2. Isn't it obvious?

      Radial velocity will also only catch an exoplanet candidate if Earth is roughly in line with its orbital plane. The gravitational microlensing approach is not as sensitive to the relative geometry, but it will also miss most exoplanets because of the time sensitivity (the exoplanet has to pass nearly between us and the distant star while the near star is transiting the distant one).

      It's all statistical; you can make assumptions about the distribution of the angles of rotation of nearby stars, and hence their ecliptic, and you adjust your estimated population of planets based on the maximum number it would be possible to detect with each method.

  8. Mage Silver badge


    That the only practical Star Ship designs are really "Generation Ships", We probably could build one or two.

    No warp or hyper drive :(

    Not even an Ansible yet.

    1. Mikel

      It makes one thing easier

      Seems that finding the right star for a destination isn't actually hard - almost any one will do.

  9. Anonymous Coward
    Anonymous Coward

    Are those aliens Christians?

    Think of all the souls to save, but the 'in God's image' thing may need a reword!

    1. Graham Dawson Silver badge

      "And other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd."

      And if you think "made in God's image" means "looks like a monkey" you're really not thinking very hard. This may be remarkably demonstrative.

    2. Adair Silver badge

      Ever heard...

      ...of a 'metaphor'? ;-)

      1. markoer

        ...which is basically what the entire Bible is... admitting an ancient collection of writings, written by dozen of people in the bronze age and arranged by even more obtuse ones during the Middle Age era, has any authority over how we were actually made.

        1. Graham Dawson Silver badge

          David Icke wrote the bible?

          Oh but to be serious, the bible isn't a metaphor. It contains a great deal of metaphor (neatly buggering up the still annoyingly popular "metaphor was only invented in the last 400 years" belief that I keep seeing EVERYWHERE), but it isn't one in total. It's a collection of sociological and historical documents charting the evolution of a set of religious beliefs over approximately 3000 years. Once understood in a correct historical context - and when parts are understood within the context of other parts - it becomes much less obtuse and much more readable.

          Well, not readable... but at least understandable. Frankly, the sheer number of misconceptions people have about scripture still stagger me. I' often staggered by how much of it I completely misread.

          And now back to Arkham City. Batman keeps dying for my sins, poor chap.

    3. John H Woods Silver badge

      "The Sparrow" ...

      ... required reading for any one with the specified missionary zeal.

    4. Anonymous Coward

      I'm not afraid of alien armies, but of alien missionaries

      I'm not worried about alien armies - if they can get here, they are either so advanced they will wipe out out instantly, or are so advanced in science they don't need our pitiful resources, and could get what they want far easier in the asteroid belt.

      No, what I am afraid of is alien missionaries - "People of Earth: have you accepted Glub as your personal saviour?" After all, look at how well that sort of thing has generally worked out in our past.

      1. TheOtherHobbbes

        The smart way

        to invade another planet is to take over a small number of leaders and opinion formers.

        You can then steer the natives towards terraforming (or xenoforming) the planet to make it more hospitable for your own requirements on the planet's own dime, without all the wasteful drama produced by giant invading armies, etc.

        Extra points for persuading the natives that none of this is happening, that - for example - temperature increases don't matter, and that possible developments in the wrong direction - like sustainable power - are a bit mad really, and no one should take them seriously.

        That way the natives can cook themselves, and you can start eating them when you're ready.

        1. Jimbo 6
          Thumb Up

          You're not wrong

          And you've saved me having to actually read any of David Icke's books.

    5. dssf

      "In "God's" Image"

      Imagine if they exist and think WE are fugly.

      Would that make us the zit of god, or the wart of god, or the cancre of god? For all we know, we could be cysts, pollops, hangnails, and the mites of God's very aged, virtual skin... hahhaha

      1. Graham Dawson Silver badge

        Again, "in the image of God" doesn't refer to physical appearance.

  10. min

    ...zillions of planets eh???

    ...but how many of them have Simon Cowell burning holes through their culture?

  11. Charles Manning
    Paris Hilton

    Stars have an average of 4 planets

    But poor PH only has one!

  12. Charlie van Becelaere


    This fellow seems to think some of these exoplanetarians are already in our neighbourhood:

  13. Anonymous Coward
    Anonymous Coward


    My vote is for non-carbon based life forms. Or should that be 'thing that'd be interesting to see'.

    1. Nigel 11

      Not mine

      The physics of chemistry is universal. There's no other element that has even half the versatility for building complex molecules that Carbon does. Single bonds, double bonds, rings with de-localised electrons, stereochemistry where one carbon is bonded to four different groups or the cis/trans arrangement around a double bond or the sequence of groups around a ring ....

      Alien biochemistry may look nothing like ours, but I'll eat my hat if it's not based on Carbon, with Hydrogen, Nitrogen and Oxygen in important supporting roles. I also think it highly likely it'll have proteins (loosely defined as long chains of amino acids, CO-NH bonded).

      1. Miek

        "The physics of chemistry is universal. There's no other element that has even half the versatility for building complex molecules that Carbon does." -- or at least you hope it does

      2. mhenriday

        Just hope, Nigel,

        that your hat is also carbon-based - after all, cannabalism is the name of the game !...


  14. Sorry that handle is already taken. Silver badge

    As reported by several ABC radio stations this morning:

    "Scientists have discovered that there are more planets in the solar system than there are stars."

    Who knew?

  15. Anonymous Coward
    Anonymous Coward

    "If the Universe Is Teeming with Aliens ... WHERE IS EVERYBODY?: Fifty Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life" by Stephen Webb.

  16. Big O

    “perhaps other coincidences in other solar systems have led to entirely different and exciting new forms of life"

    Doesn't seem to be said enough i reckon.

    1. Local Group

      "entirely different and exciting new forms of life"

      You mean like coneheads and tentacled blobs or like Kim Kardashian and Pee Wee Herman?

  17. Mad Chaz
    IT Angle

    Thanks for all the fish

    Or maybe they just all realised taking the time to build complicated space crap to invade other planets isn't as fun as frolicking in the oceans, eating fish and asking the babble fishes for a lift when they need to leave.

    1. Local Group

      Or maybe

      the jalopy they're driving is red-lined at 50,000 miles per second.

      1. Jonathan Richards 1 Silver badge


        It appears that everyone's jalopy is red-lined at 1 ly/y, and furthermore you need an infinitely large team of horses to pull you up to that speed, and infinitely large brakes to dump the energy should you wish to stop. Where is everyone? Out there, a long way away, and that's where they're forced to stay.

        1. Local Group

          "Out there, a long way away, and that's where they're forced to stay."

          "I'll have grounds more relative than yours" (pardon the pun)

          Until you have more convincing proof of the earth's alien repellent field, I will continue to sleep with the light on. But thanks for sharing.

  18. Ben 42
    Thumb Up

    PLANET, the Probing Lensing Anomalies Network

    Thumbs up for an excellent backronym. :-)

  19. Daniel Evans

    "The microlensing process can tell boffins the mass of the planet, but unfortunately, it can't give the scientists any idea of what that world is made of. Just because a world is within the habitable zone, doesn't necessarily mean it will have the life-giving composition of our own planet."

    Not quite sure how you linked "mass" to "habitable zone" there - the mass of a planet isn't necessarily linked to where it orbits (depends what theory you feel like using, and exosystems have thrown out some really odd distributions). In fact, the mass of the planet is a pretty damn good indicator of composition - if it's the mass of Jupiter, it's probably not made of rock.

  20. Martin Budden Silver badge

    common comets?

    So they've shown that our solar system is typical of most star systems in that it has several planets including some rocky ones. Isn't it therefore likely that it is also typical of most star systems with respect to comets? This would suggest that there are many exoplanets with as much water as our planet... in fact there could be one well-watered rocky planet per star on average.

  21. Frumious Bandersnatch

    Wait... having tea RIGHT NOW?

    I demand an update to the Drake equation!

  22. Lars Silver badge


    "It is very unlikely that the same circumstances would be present in other solar systems."

    Does not fit in with the rest of the speculations at all.

    1. pealla

      Does microlensing work at radio frequencies? Perhaps SETI should be aiming at these events.

  23. solaries

    Planets Around Every Star

    This is great news the more stars with planets orbiting them the better chances for finding life in the galaxy. A wonderful age to be living in what new surprises await us who knows.

    1. Local Group

      "Grandmother, what big planets you have!"

      "Grandmother, what big eyes you have!"

      "All the better to see with, my child."

      "Grandmother, what big teeth you have got!"

      "All the better to eat you up with."

      And, saying these words, this wicked wolf fell upon Little Red Riding Hood, and ate her all up.

  24. Winkypop Silver badge

    Jesus, that's a lot of planets!

    No wonder his dad rested on the 7th day....

    * and don't give me that "god's days are longer crap....."

    1. TeeCee Gold badge

      Updated version:

      Day 1: Set off Big Bang, played Scrabble.

      Rest of week: Holiday.

      Science. Making God's life easier for the last 14 billion years.

  25. damien c

    There has to be life out there

    I believe that there is life out there somewhere, because if you think about it if life on this planet started because of a comet bringing water to this planet then it has to have happened somewhere else as well.

    I think though that maybe the life which I am sure is out there, is somewhat wondering like us if they are alone and they are trying to figure out how to make it so they can travel to other planets and galaxies etc, without needing to spend years in the ship.

    I don't think I will see anything happen in my life in regard's to travelling to other planets to meet a alien species but at some point, people will no doubt be able to do that sort of thing unless they come to us 1st and either wipe us all out or decide to help us get to the same level as they are.

    Problem is with the way us humans are with war etc if we developed a way to travel to other planets how long would it be before, we wiped a country of the face of the planet or destroyed the planet to stop some country from being able to do something similar.

  26. Dick Emery
    Black Helicopters

    Age of the universe

    Of course it could be that the universe is not old enough to have any civilisation become developed enough to be able to travel the great distances needed for contact. Or it could be they have contacted closer neighbours and we are far far away out in the cold edges where chances of contact are unlikely.

    Or perhaps we have already been contacted and nobody is letting on.

    Just saying.

  27. Dave 125

    Alien religions

    It's not those asking if we've received Glub as our personal saviour we need to worry about, it's those whose Prophet Fnergle (peace be upon him) demands conversion, subjugation or death.

  28. King Jack

    Life outside this planet

    Yes. Even religious folk believe that, after all where does god live?

  29. Anonymous Coward
    Anonymous Coward

    What bugs me is...

    What do they mean by habitable, do they mean that by our very blinkered definition of the life things could be living there? We are an arrogant species even considering that we know everything about what forms life takes....

  30. Anonymous Coward
    Anonymous Coward

    Lies, Damned Lies.......

    So the study is based on 40 microlensing events, which results are then extrapolated to the 160 billion or so stars that make up the entire galaxy!

    And this is statistically significant?

    1. Local Group

      Hey, AC

      You don't have to spoil it for the rest of us.

  31. Graham Bartlett

    Having tea right now

    Actually it's more like "having tea umpty-tum million years ago", given that what these guys are seeing is light that reflected off their planet (and teacups) umpty-tum million years ago. Perhaps they've discovered coffee by now. Or maybe their civilisation has disintegrated into chaos and ruins, and they're reduced to drinking Horlicks.

  32. TeeCee Gold badge

    Habitable planets.

    I reckon the governing factor here is the 1 in 6 for gas giants.

    You may well have a handy, rocky planet in the "goldilocks zone", but without that massive gas giant further out acting as a cosmic hoover for incoming lumps and debris left over from the system's formation, as Jupiter does for us, it'll end up as a pockmarked hellhole.

  33. Majid

    It does not matter.. we are still alone

    Most of those systems are so far away that even if we detect life, and try to fly there to contact them, they will be most likely be extinct once we get there. And even if they are not, if we fly back we will find out humanity has become extinct.

    So even if we are surrounded by billions of races, we are still alone. (unless of course we invent space folding).

  34. Anonymous Coward
    Anonymous Coward

    No there aren't

    Why not fund a six year study to find the four elephants that previously carried the world on their backs? Too many academics wasting too much money for conjecture and philosophy.

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