The Milky Way Could have Billions of Earths

With the upcoming launch in March of the Kepler mission to find extrasolar planets, there is quite a lot of buzz about the possibility of finding habitable planets outside of our Solar System. Kepler will be the first satellite telescope with the capability to find Earth-size and smaller planets. At the most recent meeting of the American Association for the Advancement of Science (AAAS) in Chicago, Dr. Alan Boss is quoted by numerous media outlets as saying that there could be billions of Earth-like planets in the Milky Way alone, and that we may find an Earth-like planet orbiting a large proportion of the stars in the Universe.

“There are something like a few dozen solar-type stars within something like 30 light years of the sun, and I would think that a good number of those — perhaps half of them would have Earth-like planets. So, I think there’s a very good chance that we’ll find some Earth-like planets within 10, 20, or 30 light years of the Sun,” Dr. Boss said in an AAAS podcast interview.

Dr. Boss is an astronomer at the Carnegie Institution of Washington Department of Terrestrial Magnetism, and is the author of The Crowded Universe, a book on the likelihood of finding life and habitable planets outside of our Solar System.

“Not only are they probably habitable but they probably are also going to be inhabited. But I think that most likely the nearby ‘Earths’ are going to be inhabited with things which are perhaps more common to what Earth was like three or four billion years ago,” Dr. Boss told the BBC. In other words, it’s more likely that bacteria-like lifeforms abound, rather than more advanced alien life.

This sort of postulation about the existence of extraterrestrial life (and intelligence) falls under the paradigm of the Drake Equation, named after the astronomer Frank Drake. The Drake Equation incorporates all of the variables one should take into account when trying to calculate the number of technologically advanced civilizations elsewhere in the Universe. Depending on what numbers you put into the equation, the answer ranges from zero to trillions. There is wide speculation about the existence of life elsewhere in the Universe.

To date, the closest thing to an Earth-sized planet discovered outside of our Solar System is CoRoT-Exo-7b, with a diameter of less than twice that of the Earth.

The speculation by Dr. Boss and others will be put to the test later this year when the Kepler satellite gets up and running. Set to launch on March 9th, 2009, the Kepler mission will utilize a 0.95 meter telescope to view one section of the sky containing over 100,000 stars for the entirety of the mission, which will last at least 3.5 years.

The prospect of life existing elsewhere is exciting, to be sure, and we’ll be keeping you posted here on Universe Today when any of the potentially billions of Earth-like planets are discovered!

Source: BBC, EurekAlert

35 Replies to “The Milky Way Could have Billions of Earths”

  1. I’d say Gliese 581 c is much closer to Earth than CoRoT-Exo-7b. CoRoT-Exo-7b makes 51 Peg b look like paradise–and 51 Peg b is a hot Jupiter.

    Gliese 581 c is, in the very least, near the habitable zone, and it’s minimum mass is much closer to Earth’s mass.

  2. I am certain there are other Earth-type worlds
    and have the same type settings and environment,but such advanced life forms only lasts about 25% of their stars revolution around the Milky Way before they become extinct. Such worlds with advanced lifeforms
    existing now is too far to communicate, and the galaxy is littered with millions of probes launched by lifeforms no longer in existence,
    perhaps far into the future, we can ‘capture’ a ‘extraterrestrail’ probe.

  3. There is no reason to doubt that the laws that govern our corner of the Milky way do not also govern in the rest of the Univers.
    So there is no reason to doubt there would be stars with earthlike planets such as ours.
    The Universe, will slowly be recognised as filled with life forms. Distance, is the biggest problem, though it may also be our biggest safety net.

  4. Kepler will be the first satellite telescope with the capability to find Earth-size and smaller planets.

    I think the CoRoT team will quibble with you on this one. Detection of earth-size planets may not have been within the original mission parameters, but after the commissioning phase they found that the quality of the telescope was so good that they believe they have a good chance of detecting Earth-size planets. I’m sure they’re busting a gut to beat Kepler to the punch!

    Either way, things are about to get more exciting. 🙂

  5. Thank you for putting this news in a much better perspective than the sensationalist media types who first ran the story. They quoted ‘100 billion trillion’ possible earths in the universe. Quite a bit more than the estimated number of stars in the observable universe! Sometimes you can just shake your head.

  6. I think the most powerful guiding principle in cosmology has essentially been: our place and situation in the universe is about as ordinary as it can get. With this principle firmly in mind, I would not be in the least surprised to see many Earth-like worlds emerge as the technology allows, and for a significant number of these to have the potential to foster life.

    To be honest though, ‘life’ is pretty far down the list on what excites me about astronomy, despite the fact that I’d be elated by any confirmation that it was out there. I essentially expect it I guess.

  7. don’t forget we need to have a large moon like ours as well to get things moving, and maintain the rage so to speak

  8. “Earth-like” means about same mass and size? Then their guess seems reasonable.
    Perhaps we will have at least part of the answer in nearest decades?
    Another thing: It may be worth study “un-earth-like” planets – and objects too. Especially those not orbiting a central star like our.
    Astronomers theories of stellar evolution from beginning to end is rather well established(?) The next may be theories for “planets” – and other “small-dark” objects.
    (We even could get some ideas of possible futures for earth and solar system).

  9. Earth size; most likely. Like Earth? I want to believe, but historical contingency which is the pervasive operator for all things which exist in the Universe, and which gave us Earth and Life is a powerful and relentlessly unforgiving process, producing in our Universe many unique and complex things for which there is no duplicate. When I contemplate the myriad chance events, each unique and each necessitating a cascade of chance events, unique and necessitating in their own turn, all of which must necessarily come together in unique ways, that is, having exactly the same historical contingency, to produce the sine qua non of life as we understand it–an Earth-Moon system– exactly where it is in its exact orbit, with its companion planets exactly as they are in their exact orbits about a sun exactly like ours, in a solar system exactly like ours, I am hestitant to think that such events are duplicated even once, much less abundantly, in a finite Universe.

  10. I don’t agree with the idea that life on those planets will necessarily be similar to pre-historic Earth. There is no reason to believe that life on those planets won’t be well more advanced than us. The big goal should be getting to one of those uninhabited planets and leaving all these war-mongering, light-polluting, fossil fuel burning, nincompoops behind. Regardless, once Kepler is up and running, I think Earth-like will be the rule, rather than the exception.

  11. Paul, that is completely arrogant to think that. Life evolved on Earth with a moon, point taken, but that is exclusive to this planet and how life evolved here. I think of it as, we are not here because of the moon (f.e.), the moon just happened to be there and so it helped life to evolve into what it is today. If the moon wasn’t there then life might be totally different.
    And i hate this “habitable zone” talk about where to look for life. Obviously its the first place to look as conditions are similar to ours but a hell of a lot of people dismiss the possibility of life evolving on planets outside the “habitable” zone.
    Anyway, i believe our future is out there in the cosmos.

  12. Shouldn’t the answer to the Drake Equation range from *one* to trillions? We know it’s definitely not zero… 🙂

  13. The skeptics have always been proved wrong and will continue to be. Why are some people so parochial?. We will find that the Universe is more complex and diverse than we have imagined so far.

  14. “…we MAY find an Earth-like planet orbiting a large proportion of the stars in the Universe…
    PERHAPS half of them would have Earth-like planets…the LIKELIHOOD of finding life and habitable planets outside of our Solar System…Not only are they PROBABLY habitable…There is wide SPECULATION about the existence of life elsewhere in the Universe…The PROSPECT of life existing…”


  15. Earth like re: definition? Rocky planet in the goldilocks zone?

    Wouldnt Venus and Mars (and the innumerable variations between) would be considered earth like, from an astonomical POV?

  16. I do believe there could be simple lifeform liken to what we know as bacteriums,etc under Europas’ ice, a few other moons of the giant planets, but, I’d rather such life stays there—to bring them to Earth is well, lets just say that will be foolish at the least!!!

  17. “Shouldn’t the answer to the Drake Equation range from *one* to trillions? We know it’s definitely not zero…”

    Zero, and something very close to zero, are possible outcomes also. In that case, we are extremely improbable (or miraculous :P)

    Our existence is not evidence of life being probable. If we exist, we will observe ourselves no matter how rare or common life is. Any intelligent life in any universe will always observe at least 1 case, even if there is only a 0.0000000000000001% chance of life existing in that universe.

  18. # Chris Says:
    February 17th, 2009 at 1:58 pm

    “one step closer to proving creationism is poop yeah!”

    You reckon finding other Earth-like planets with life on them will dissuade creationists huh? Gotta love an optimist!

  19. Dr. Boss sure knows how to draw attention to himself, maybe this will help him get more funding in the future.


    You want certainty? Build a starship (or at least a telescope with a mirror 100 miles across) and go see for yourself.

    In the meantime, we have to work with the best data we have. And there’s nothing wrong with reasoned speculation based on that data, as long as you remember that reasoned speculation is all it is…

    “Our existence is not evidence of life being probable.”

    No, only that it’s possible.(‘Zero?” I don’t know about you, but I think, therefore, I am.)

    The possibility is reason enough to look for more data points, and make the best estimate you can as to where they may be found. Then, as noted above, go find them.

    Unless you accept UFOs, proof doesn’t seem in a hurry to come to us…

  21. Still waiting for them to find the first one, let alone the billionth one!
    But what do we do with them when we find them or catalogued them? Sure astrophysically and astronomically it might be important for our understanding of the universe, but what do you do with them once you find them? Visiting them remains out of the question probably for millennia, if at all, due to the sheer immensity of space.
    Next we will be hearing complains that these planets are out there and government is hiding and covering up information about all the aliens that are living there!

    Life bad enough on Earth, why make the rest of the universe just as miserable?

  22. Salacious B. Crumb- LMAO-if these ‘conspiracy’ thinkers quit using drugs and watch these ‘conspiracy’ TV programs, and watch the Science and Discovery channels, they will find even if we found a planet with ‘aliens’ in the Alpha Centari system at 1.34 parsecs, or 4.37 light year distance, the communications will be very boring!!!The speed of the Voyager at 17.1 km/s or 61.600km/h may seem fast, but after almost 32years of travel,is only 14.8 light hours away-it will be a very boring journey as it will take about 50k years to get at that distance!!!!. Then these ‘conspiracy’ thinkers will think the government has a nuclear powered vehicle already made-geeez,even if it can be made which is centuries away, the ‘fuel’ will require a mass of 10–20x of the craft! Even if the craft can reach 10% SpeedOfLight, still over 50 years 1 way journey, very boring, and perhaps the craft would need a 24meter shielding of lead to protect against hydrogen particles smashing into the front of the vehicle in so call
    ’empty space’ besides the dangers of the nuclear power plant. As far as I’m concerned, it is best advanced lifeforms out there is too far away from each other and has a finite life before becoming extinct.

  23. …is there anybody out there?… your PINK FLOYD asked the right Question.
    Chances are (;)and I am living proof, haha), that life CAN + MUST exist out there.
    If there are vastly advanced civilizations and look at this planet, it is probable, that they conclude: well, let’s wait until they either become extinct, or manage to live with the environment, not at its cost.
    A.C. Clarke made it clear in SPACE ODYSSEY’s 2001/10: the carbon copies have just not fathomed what is needed to be respected by other alien lifeforms…
    May the creator(s) bless you “CARBON COPIES”!

  24. well, our only example is our solar system. We have one habitable planet orbiting one sun. So we could ASSume that for every star out there, there is at least one habitable planet in orbit….. what if our example is the rule, and not the exception?!

  25. Chris said: February 18th, 2009 at 6:19 pm
    lets just hope the missionaries keep away

    LMAO, too.

  26. “lets just hope the missionaries keep away” ROTFLOL the last thing we want is christian aliens

  27. Forget traveling to these far away places, just knowing something other than earthlings are out there would change everything, perpectives, views, ideologies just to name a few. With the number of stars alone there has to be something. Surprise me!

  28. the Milky Way might be at least 46 billion light years away from Earth it’s self!
    The milky way is the best thing to do a report on!!!


  29. milky milk !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    whats the fastest way to get milk!!!!!!!!!!!

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