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Space Science

Kepler Investigator Says 'Galaxy Is Rich In Earth-Like Planets' 206

Posted by kdawson
from the member-of-a-larger-club dept.
astroengine writes "In a recent presentation, Kepler co-investigator Dimitar Sasselov unexpectedly announced news that the Kepler Space Telescope has discovered scores of candidate Earth-like exoplanets. Not waiting for the official NASA press release to announce the discovery, Sasselov went into some detail at the TEDGlobal talk in Oxford, UK earlier this month. This surprise announcement comes hot on the heels of controversy that erupted last month when the Kepler team said they were withholding data on 400 exoplanet candidates until February 2011. In light of this, Sasselov's unofficial announcement has already caused a stir. Keith Cowing, of NASAWatch.com, has commented on this surprise turn of events, saying it is really annoying 'that the Kepler folks were complaining about releasing information since they wanted more time to analyze it before making any announcements. And then the project's Co-I goes off and spills the beans before an exclusive audience — offshore. We only find out about it when the video gets quietly posted weeks later.' Although Sasselov could have handled the announcement better (and waited until NASA made the official announcement), this has the potential to be one of the biggest astronomical discoveries of our time — so long as these Earth-like 'candidates' are confirmed by further study."
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Kepler Investigator Says 'Galaxy Is Rich In Earth-Like Planets'

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  • Unconfirmed planets (Score:4, Informative)

    by AC-x (735297) on Tuesday July 27, 2010 @07:57AM (#33043164)

    Kepler needs 3 transits to confirm a planet, so given that it's only been up there since March 7, 2009 any planet around the same distance as earth will only have had 2 transits max.

    It's exciting that there are so many candidates but I guess NASA doesn't want the embarrassment of getting everyone all excited then having to hugely backtrack on the number if some turn out to be something else.

  • by yotto (590067) on Tuesday July 27, 2010 @08:33AM (#33043720) Homepage

    And while 400 planets sounds like a lot, in the milky way it isn't much at all, especially if you consider the short timespan that humans have been capable of even seeing into deep space let alone make their presence known. And there are countless disasters that can wipe out a civilization.

    It's not 400 planets in the galaxy. It's 400 out of 700 planets they've looked at. That implies 4/7ths of the planets in the galaxy are "Earth sized."

    Interestingly, this matches up with what we have in our own Solar System, where 4/8ths of the planets are just so sized. Does Mercury count? Maybe it's 3/8ths here. Dunno. Still close enough for statistics.

  • by sznupi (719324) on Tuesday July 27, 2010 @10:18AM (#33045422) Homepage

    But we do have it, that's the point. And "planet" simply means one type of planetary bodies already.

    Dward planet, terrestrial planet, gas giant (among them distinction between neptunes/jupiters and hot/cold), sub-brown dwarf; iron planet, chthonian planet, carbon planet, ocean planet, trojan planet, rogue planet...there's plenty of different classes.

    Now you'd want to replace descriptive and flexible monikers with rigid symbol classifications?
    OK, so perhaps, maybe, you're used to Star Trek fantasy setting, which also nicely covers most of the latin alphabet...but here, let me show you how it would look in practice:

    Class (put in one symbol from this alphabet [wikipedia.org],; /. & unicode...) Planet
    Class (put several, if some body is like that) Planet

    And you know, the best would be to just settle with what a planet was for Greeks - that includes the Moon and the Sun... - but with Star Trek classification system.

  • by delt0r (999393) on Tuesday July 27, 2010 @10:33AM (#33045708)

    If there is no faster then light method of travelling possible, then there are unlikely to be any visitors ever. End of story.

    This is quite false. You have left out a entire section of very possible developments.

    • Longevity treatments. Whats 100 years when you live for 1000?
    • "Cryo sleep" or suspended animation. No reason why it can't work.
    • "Generation ships". No reason why a big arse space ship wouldn't be a pleasure to be part of. Even if you don't care about the destination.
    • robotic overloads. You don't need AI here.

    Note that nuclear fission fragment rockets can get ~5% C. Antimatter much more... sure we aren't doing it now. But there is no physics stopping it. Unlike FLT.

    All we are missing is the desire or need to go in the first place.

  • by Chris Burke (6130) on Tuesday July 27, 2010 @10:44AM (#33045918) Homepage

    I agree. Water presence? Temperature within habitable range? At least a primordial atmosphere? Not sure if Kepler is the right tool to collect that kind of data, but to call them "earth like" seems premature.

    Exoplanet spectroscopy has been done, but is a very new science and extremely difficult. And first, we have to be looking at a specific planet with specific instruments.

    Kepler, on the other hand, is continuously monitoring a region of the sky and some hundreds of thousands of stars for signs of planets. It detects planets by the "transit method", which means you watch all the stars, and see if any of them dim slightly. You keep watching and if you see it dim again, you might have found a planet (rather than a one-time passing object between us and the star). To be fairly sure it's a planet, you need to see a third dimming with the same time delay as between the first two, showing that it's periodic. Ideally you want to see a 4th event to confirm, but 3 is good enough to call it a candidate -- or maybe they say candidate after 2? I'm not sure.

    Note that this means Kepler only sees planets whose orbits happen to be about "edge on" from our perspective. So there could be many systems that Kepler simply can't see -- and given how many it has seen, I think it's safe to say that there are many such systems.

    Anyway, from this data, Kepler can figure out the approximate orbital distance and mass of the planet. That's it. You can estimate temperature from proximity to the star, too.

    Personally, given Kepler's limited-but-awesome capabilities, I wouldn't mind them saying "earth-like" simply to describe roughly earth-size planets that are in the habitable zone of their star. But I doubt that's the case for most of these, since Kepler has only been running for half a year, and for Kepler to detect something in an earth-like orbit around a Sol-like star, it would take between 2 and 3 years of observation. The only planets Kepler can find up to this point are ones that orbit closely to their star. So most of these are not going to be in the habitable zone.

  • Re:Kepler (Score:3, Informative)

    by Chris Burke (6130) on Tuesday July 27, 2010 @10:48AM (#33045992) Homepage

    There are 'super Earth' planets, but at those distances we really don't know how much gas vs rock there is.

    Well we kinda do, because we can also measure the size of the planet, and based on that get its density. The super-earths appear far too dense to be gaseous.

  • by Anonymous Coward on Tuesday July 27, 2010 @01:31PM (#33048768)

    If there is no faster then light method of travelling possible, then there are unlikely to be any visitors ever. End of story.

    FTL would be nice to have, sure, but it's hardly essential. If we'd launched a 1/10th lightspeed probe towards Alpha Centauri during the Apollo era, it'd be arriving just about now.

    Yes, 0.1c is a hell of a lot faster than any spacecraft out there so far, but it's within the bounds of conceivable technology. Who knows what conceivable technology will be a century from now -- both in terms of propulsion and longevity.

  • Re:Kepler (Score:3, Informative)

    by cusco (717999) <<moc.liamg> <ta> <ybxib.nairb>> on Tuesday July 27, 2010 @03:04PM (#33049948)
    "how large can a rocky planet be before it has a significant atmosphere?"

    Depends on its initial orbit, final orbit, and the cloud it condensed out of. Too close to its star and the gasses get blown off, too far away and they freeze out. Too little iron and the magnetic field is too week to protect it from the solar wind. Too much hydrogen and not enough other gasses and it escapes to space. Too few comets in the cloud and it never accumulates enough water for reflective clouds.
  • Re:Who cares? (Score:3, Informative)

    by fyngyrz (762201) on Tuesday July 27, 2010 @08:14PM (#33052670) Homepage Journal

    these planets are NOT "all in short, close orbits"

    Wrong. Kepler only sees close in earth sized planets, with almost no exceptions. Even though it's looking at the same area over a long time.

    The reason for this is that for Kepler to see a transit of an earth sized planet, said planet has to occult the star; which in turn means that the planet's orbit has to lie on a plane defined by us and the target star, within a margin of error defined by the planet's diameter against the cone defined by the star at one end and the telescope at the other, which, with an earth like planet, is damned small.

    So the further away an earth sized planet gets from its star, the less likely you are to spot it, even with just the slightest deviation for the orbital plane. The consequence of this is that earth sized planets are spotted close in, and basically nowhere else except against extreme odds. Larger planets are spotted because the orbital plane can be significantly more tilted and still result in occultation.

    And, even when you *do* spot the earth sized ones that aren't close-in, you still can't tell much about them. They might be like Venus and boil metals, or they might be like mars and freeze your butt off, or anywhere in between, and even if you could tell *that*, you still wouldn't know if they were supporting life.

    So again, we're back to needing an optical telescope that can actually resolve the planets, see clouds, continents, etc. Long baseline, multiple aperture, etc. We should do it ASAP. Just keep firing units up there until we have a huge array over millions of miles. Now that would be a telescope worth having. No single aperture instrument is going to tell us anything really interesting about any planet outside our solar system. All they see are indirect hints.

  • by Chris Burke (6130) on Wednesday July 28, 2010 @10:08AM (#33056678) Homepage

    Isn't our solar system's ecliptic plane closely aligned with the galactic plane?That's what I remember from the last time I actually looked at the Milky Way up in the sky, anyway.

    No, it's actually close to perpendicular. Earth is tilted relative about 30 degrees to the solar ecliptic, still well off the galactic plane. That's why the Milky Way kinda goes diagonally in the sky, and the planets usually don't appear in it.

    I had always assumed this was for the same reason that the plane of rotation of most of the planets are aligned with their planes of revolution around the sun...

    It is very similar. Think of the planets as systems orbiting the sun much like the solar system is relative to the galaxy. Overall the planets orbit in the same plane around the sun since the planetary system is drawn towards the solar plane and the overall angular momentum. Each planetary system though has its own angular momentum and rotation plane. Some are wildly skewed from the solar plane. For the moons around the planets, the planet is the dominant source of gravity. Just like for the planets, the sun is dominant and the tug towards the galactic plane is very tiny.

    I'm not sure if there's any bias at all, but having other star systems appear edge on to us is more or less a matter of chance. So of all the stars Kepler is looking at, only a small fraction of planets are even possible for it to see. Which makes the number it has already discovered that much more amazing.

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