This is not a NASA Website. You might learn something. It's YOUR space agency. Get involved. Take it back. Make it work - for YOU.
Astronomy

There Are Lots of Earth-sized Planets Out There

By Keith Cowing
NASA Watch
January 7, 2013
Filed under , ,

At Least One in Six Stars Has an Earth-Sized Planet
“The quest for a twin Earth is heating up. Using NASA’s Kepler spacecraft, astronomers are beginning to find Earth-sized planets orbiting distant stars. A new analysis of Kepler data shows that about 17 percent of stars have an Earth-sized planet in an orbit closer than Mercury. Since the Milky Way has about 100 billion stars, there are at least 17 billion Earth-sized worlds out there.”
NASA’S Kepler Mission Discovers 461 New Planet Candidates
“NASA’s Kepler mission Monday announced the discovery of 461 new planet candidates. Four of the potential new planets are less than twice the size of Earth and orbit in their sun’s “habitable zone,” the region in the planetary system where liquid water might exist on the surface of a planet. Based on observations conducted from May 2009 to March 2011, the findings show a steady increase in the number of smaller-size planet candidates and the number of stars with more than one candidate.”
Earth-Size Planets Are Common in Our Galaxy, University of California Berkeley
“An analysis of the first three years of data from NASA’s Kepler mission, which already has discovered thousands of potential exoplanets, contains good news for those searching for habitable worlds outside our solar system. It shows that 17 percent of all Sun-like stars have planets one to two times the diameter of Earth orbiting close to their host stars, according to a team of astronomers from the University of California, Berkeley, and the University of Hawaii at Manoa.”

NASA Watch founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.

39 responses to “There Are Lots of Earth-sized Planets Out There”

  1. meekGee says:
    0
    0

    It will be interesting if it is found that the majority of habitable worlds are actually satellites of gas giants. (Since rocky planets are more common in too-tight orbits)

    For civilizations on such worlds, it will be clear from “day one” that they are orbiting around a sphere, and so that they are likely living on one too.

  2. npng says:
    0
    0

    17 Billion Earth sized Worlds?  Wow.  Probablistically, I wonder how many have to deal with republican and democrat fights, fickle fiscal cliffs, sequestration, economic stresses, war, corruption, indifference and wandering space visions?  Given billions of habitable planets around we may just seem a run-of-the-mill average World, but we still have a chance at uniqueness given our human ways.

    • Steve Whitfield says:
      0
      0

      npng,

      I’m interested in what portion of 17 Billion Earth-sized worlds have any form of life at all; and more important than that, how many have “intelligent” life?; and most important of all, how many have “intelligent” life fortunate enough to enjoy two complementary and compatible genders?

      Steve

    • David says:
      0
      0

      Earth sized doesn’t mean habitable, in fact in other versions of the article scientists point out that they still don’t have the data to determine Earth-like worlds. Earth sized also means planets of Earth size in orbits like Mercury-so not habitable

    • Michael Spencer says:
      0
      0

      you mean Democratic, yes?

  3. dierakete says:
    0
    0

    Uh oh.  Falling Skies – here we come.

  4. Russell says:
    0
    0

    wonder why they’re focusing on planets with a orbit shorter than ours (hence closer to the sun = less habital ?)  are these easier to detect ? (less observations needed)

    • Geoffrey Landis says:
      0
      0

      Correct: the closer to the star, the easier a planet is to detect.
      This is true for two reasons.  First, they can only see a planet that transits, that is, passes between the star and the observer, and the closer the planet is to the star, the more likely that is.  Second, they need to see several orbits, to make sure it’s a planet and measure its period, and hence closer in orbits, which move faster, can be seen sooner.  The more transits you see, the easier it is to separate the signal from the noise.

  5. Stuart J. Gray says:
    0
    0

    The way that Kepler works, it could not have found most of the Earth sized planets in the habitable zone yet. That is why they have so many “candidates”. I suspect they will verify a LOT more as the extended mission brings in more data. They will just keep operating it until it runs out of fuel.

    • whabbear says:
      0
      0

       Stuart: Not quite correct. All potential planets in the KOI catalog are candidates until they are verified by means other than direct Kepler data, such as followup observations by Earth-based telescopes of radial velocity indicators.  The reason Kepler hasn’t yet detected any true earth-mass planets in the habitable zone of sun-like starts is that A) they’ve analyzed less than two years of data, and B) most sunlike stars have turned out to be more variable in their light output than was expected.

  6. TheBrett says:
    0
    0

    The article didn’t say whether the four promising Super-Earth candidates are “MEarths” (orbiting red dwarf stars) or not. 

  7. Steve Whitfield says:
    0
    0

    Maybe it’s time to revise some of Drake’s parameter values used in his equation?  Fermi makes good sense, but my money is still on Sagan, because that would be by far the more interesting possibility.

    • Robin Seibel says:
      0
      0

      The Drake equation is technically an equation, but it’s certainly not a scientific one.  Only three of the seven parameters in the Drake equation have scientific support.  The other four parameters are purely speculative.

  8. Todd Austin says:
    0
    0

    By assuming that it would be ‘visible’, you assume that they have chosen to use the same primitive technologies for communication as we use at the dawn of our space age. Perhaps there is something better that we haven’t found yet. It would seem to me that the safest assumption is that we know almost nothing.

  9. meekGee says:
    0
    0

    Maybe they’re just as arrogant though.  🙂

    (And, is there any reason to think they aren’t as destrictive?  After all, it seems logical that the same forces that shaped us (e.g. competition for resources) are at play everywhere.   I doubt we’re particularly good or bad in that respect.

  10. chriswilson68 says:
    0
    0

    “Which suggests that the real answer to the Fermi Problem is that `Something very BAD happens to just about all technologically inclined
    intelligent species as they age.’  Which suggests bad things probably
    lie ahead for us.”

    No, the Drake Equation has seven terms, and you’re only considering three of them (fp, the fraction of stars with planets; ne, the average number of planets that can potentially support life per star that has planets; and L, the length of time a civilization releases detectable signals into space).

    You’re completely ignoring two critical unknowns: fl, the fraction of planets suitable to life that actually develop life; and fi, the fraction of planets where life develops that actually go on to develop intelligent life.

    We have no idea about either of these values.  Either or both might be incredibly small.  They could be so small that even with the truly vast number of planets out there, ours is the only one on which intelligent life ever did, or ever will, evolve.  Or maybe not.  We just don’t know.  At all.

    http://en.wikipedia.org/wik

    • Robin Seibel says:
      0
      0

      It doesn’t much matter as the Drake equation is just a famous exercise in speculation, not a scientific exercise.

  11. chriswilson68 says:
    0
    0

    The Fermi Paradox doesn’t rest on any assumption about extraterrestrials being destructive.  It’s simply a statement that given how many likely other planets there are out there, it’s surprising we don’t see evidence of any other civilizations.

    But, actually, the Fermi Paradox isn’t really a paradox at all.  It only seems like a paradox because of our faulty intuition.  Our intuition is that if there are lots and lots of planets out there, surely some of them have evolved intelligent life.  But that’s just because our brains didn’t evolve to have very good intuition about the possibility of certain probabilities being very, very small.  If the probability of any given planet that is suitable to life actually evolving it is very, very small, that can completely balance out the very large number of planets out there and still make it likely that we’re unique in the galaxy — or, in fact, possibly in the entire universe.  As long as we don’t know the chances of life evolving, or the chances of life evolving into intelligent life, we just don’t know if the probability is very very low, so we shouldn’t be surprised that we don’t see other civilizations out there — we shouldn’t call the Fermi Paradox a paradox at all.

    • whabbear says:
      0
      0

       Chris, you have it exactly right. The other two “great filters” may be an extremely low probability that a planet has the right environment to host abiogenesis, the transition from lifelessness to microbial life, and a very low probability that microbial life evolves into intelligent life. Each of these transitions could be rare enough to solve Fermi’s paradox, even if all intelligent species become star-faring. And don’t forget the time parameter. It took 4.5 billion years for intelligent life to arise on the Earth. If we’re within even 1 SD of the mean for that value, it could be that other intelligences are only just “now” appearing across the universe.  If the nearest such intelligence is, say, outside the local group of galaxies, the chances of detection are virtually nil.

  12. Tritium3H says:
    0
    0

    A few “not so nice” answers to the Fermi Paradox:

    Greg Bear’s “Forge of God” and the sequel “Anvil of Stars”
    Peter Watt’s “Blindsight”
    David Brin’s short story “Lungfish”, recently fleshed out into his latest novel “Existence”.

  13. Scot007 says:
    0
    0

    Russell:

    Kepler potentially gets a “hit” on each transit, and you would like at least three detections to feel confident that you have seen a transit and not some event intrinsic to the star.  For a solar type star, orbital periods that fall in the so called habitable zone, range from several months to around 2.5 years, so three events would take something like a year of observing to over seven years if the planet is at the outer edge of the zone.  It would take three years for a Kepler of another civilization to detect the Earth with confidence, and the Kepler team would like better statistics than three events for small signals (like those caused by an Earth sized planet).  That is why you hear about the shorter period detections, and less about planets with longer orbital periods unless they are big planets with strong transit effects. 

  14. Edward Lu says:
    0
    0

    Maybe most civilizations never get around to solving the asteroid problem.  On this planet, we have a “civilization ender” about once every million years.   
    http://edlu.com/alien-civil

  15. Odyssey2020 says:
    0
    0

    I remember watching COSMOS and Carl Sagan was telling a bunch of 1st graders by the time they got to be his age they’d know if there were other planets circling stars way out there. 

    Well, turned out by the time those 1st graders were 21 (instead of 45!) they found out the answer is yes! 

  16. James Lowery says:
    0
    0

    WHEN can we GO then!! Some of us want to get away from all the NUTS on this planet!! LOL

  17. Robin Seibel says:
    0
    0

    The great filter is another speculative tool, not a scientific one.  Whether or not life elsewhere in the Universe exists, it’s obvious given the small area searched, the very small bandwidth of the EM spectrum that has been searched, and the handicap that the 1/r^2 falloff of signal intensity and the resultant decrease in SNR…uhm, we shouldn’t be surprised that we’ve detected nothing.  The probability of detecting such a signal given the physical constraints is not in our favor.

  18. VictorGDMoraes says:
    0
    0

    Soon find a planet like Earth, to every inhabitant of Earth. I want a planet just for me and my girlfriend! It will be called “New Eden.” I’ll create aliens cows, pigs, and chickens, and plant some kind of grain much like corn. When can I get to choose my planet? 🙂

  19. David says:
    0
    0

    The answer to Fermi paradox is probably banal-too much time difference and too much distance in space to make any contact. Mostly likely no civilization managed to expand beyond local sphere of influence over whole galaxy, and if there was one, it was a conservative one that prohibits replicator probe swarms from happening that could intervene with more primitive life.

  20. Robin Seibel says:
    0
    0

    I didn’t mention lasers, but since you did, it’s important to note that to see one, it would have to be pointed at us, a very remote possibility.  Also, given the vast distances the falloff in laser intensity would still be huge as a result of beam divergence.

    As for travelers, we’re less likely to see travelers than we are to detect signals from other life if it is out there.

    As for Dyson spheres and star towing, their fictional status doesn’t have any significance in searching for planets or the detection of life elsewhere in the Universe.

    • David says:
      0
      0

      “As for Dyson spheres and star towing, their fictional status doesn’t have any significance in searching for planets or the detection of life elsewhere in the Universe.”
      You are incorrect, Dyson Sphere searches have been conducted by scientists and astronomy institutes, and Kepler itself will be used to search for Dyson spheres

      • Robin Seibel says:
        0
        0

        People have also searched for BigFoot.  Searching for a Dyson sphere is just searching for something as a wild guess. There is absolutely nothing objective that indicates any civilization elsewhere in the universe, if there are other civilizations, would  build a Dyson sphere.  It’s just a wild guess.  That’s all.

    • David says:
      0
      0

      “Astronomer Geoff Marcy, who kicked off the search for extrasolar planets 20 years ago, plans to rummage through data from the Kepler space telescope in search of evidence for civilizations advanced enough to have built massive orbiting “solar” power stations.”
      http://www.astrobio.net/pre

      It’s not the first search for such objects btw. There are also proposals to search for signs of interstellar spaceships, asteroid mining and in more distant future, signs like city lights/ship lights on directly imagined planets.

  21. Joe Cooper says:
    0
    0

    “appliy to lasers and other beams”
    No.The data that spawned this discussion suggests there may be billions of earth-like worlds. There is no logical reason for anyone in the galaxy to intentionally ping us, and especially no reason to assume that a hypothetical ping would arrive here while we’re looking.Evidence of human civilization is observable no more than several dozen lightyears out. That includes city light which, while bright now, was not. (See North Korea for example.)

    There isn’t even a good reason for us to mindlessly go spread across the entire galaxy for the foreseeable future; if we successfully colonize Mars, we’re pretty much on safe ground for a hundred million years.

    I might as well say I don’t believe Idaho exists because I can’t pick up any radio stations from them. It’s just hard to do in Poland, unless someone in Idaho intentionally contacts me, and I don’t know anyone and Idaho and vice verca.

  22. jimlux says:
    0
    0

     lasers are no different than radio when it comes to inverse square spreading. The wavelength is short, so you can get a very large antenna (and correspondingly small beamwidth) in a smaller physical package, but, it still spreads.

    If you want a non-inverse-square mechanism from finite size, you need to send “things”: particles, a spaceship, etc.