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Space Sci-Fi Science

Could An ExtraTerrestrial Find Earth with a Telescope? 179

Posted by Zonk
from the helloooo-up-there dept.
Active Seti writes "If aliens were hunting life outside their own planet, could they peer through the vastness of space and lock onto Earth as a likely home for life? Researchers say with a roughly Hubble-sized array observers could measure Earth's 24-hour rotation period, possibly leading to observations of oceans and the chance of life. 'They would only be able to see Earth as a single pixel, rather than resolving it to take a picture,' said Astronomer Eric Ford. 'But that could be enough for them to identify our planet as one that likely contains clouds and oceans of liquid water.' The research will be useful to astronomers designing the next generation of space telescopes on our planet, because it provides an outline of the capabilities required for studying the surfaces of Earth-like worlds."
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Could An ExtraTerrestrial Find Earth with a Telescope?

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  • by ILuvRamen (1026668) on Saturday December 22, 2007 @12:40AM (#21788368)
    We should totally arrange some stars into a smiley face or big arrow pointing at us then (yes I know that would only look right from certain angles, it's a joke). But you've got to wonder why some other super advanced civilization didn't move some stars around to circle themselves or something and make it really obvious where they lived.
    • by edwardpickman (965122) on Saturday December 22, 2007 @12:51AM (#21788436)
      They probably did it's just their smiley face has five eyes and no mouth. The stars spelling out "We Are Here" are tough to read given the language differences and they use a pentagon to point instead of an arrow given they never developed archery. Celapods have trouble with bows. There is hope of translating the "Free Beer" part of the sign if we can only figure out the translation for beer. We do know there's an exclamation mark like symbol at the end of what's thought to be the word Beer. We know it as Orion's Belt.
    • Re:I've got an idea (Score:5, Interesting)

      by AKAImBatman (238306) <akaimbatman@gmai ... m minus language> on Saturday December 22, 2007 @12:53AM (#21788450) Homepage Journal

      But you've got to wonder why some other super advanced civilization didn't move some stars around to circle themselves or something and make it really obvious where they lived.

      Impracticality? I mean, moving a star takes a tremendous amount of energy. Either that, or a massive gravitational mass that can be moved through more conventional means. (One of the drawbacks of stars is that you can't exactly setup thrusters on the surface of a flaming, gaseous body.) If they were even close to such technology, it would actually be easier to send out explorers than to muck around with the position of stars.

      Assuming that such a civilization could even exist. Which is (unfortunately) somewhat doubtful. Everything we know so far suggests that life is exceedingly rare in the universe. Rare enough to make it difficult to find another civilization that used to exist, much less one that you can actually contact. (Don't even get me started on the incredible time scales by which the older civilization would be long dead before we could even see each other.)
      • I don't think an advanced civ. would even want to talk to us. They have their shit sufficiently together to travel interstellar distances so why would they even want to talk to a planet that can't even provide food to all its people and who kill each other and who have come close to complete annihilation not once but twice?

        They might send some exo-sociologists and maybe beam up a few cows and hicks but that's it. We would be poison to them. They might even set up a few quarantine beacons outside the solar s
        • by GooberToo (74388)
          a planet that can't even provide food to all its people and who kill each other and who have come close to complete annihilation not once but twice?

          Because maybe they just found food and water for their people? And space to expand? ;)
        • Why would they want to talk to us? Because we're here.
      • One of the drawbacks of stars is that you can't exactly setup thrusters on the surface of a flaming, gaseous body.

        But while we're talking about impracticalities, you could have an easier time extinguishing the side facing the direction you want it to move.
      • by vertinox (846076)
        (One of the drawbacks of stars is that you can't exactly setup thrusters on the surface of a flaming, gaseous body.)

        Well if such a civilization had reached a technological singularity event, most likely they've got a lot of time on their hands since they would have figured out how to avoid mortality by old age and would most likley use something like a gravity well to shift the stars slightly over billions of years.

        Rather than push the start, they could move it in the direction of said gravity well over tim
      • by sploxx (622853)

        Impracticality? I mean, moving a star takes a tremendous amount of energy.

        Correct, but maybe we're closer in moving stars than we may think (Yes, I'm speculating... but I always thought about this idea and I never saw it discussed, so please tell me where I'm wrong in the following: :-)

        Maybe we could exploit the chaotical movement of stars (or other big masses) and, with a really powerful
        simulator, could predict which small nudge could change the positions of the stars in a (short timescale) predictable way. This maybe would
        enable us to produce large scale patterns in the univer

      • by instarx (615765)
        Everything we know so far suggests that life is exceedingly rare in the universe.

        Face it - that was a really dumb thing to say. We have no way to know how common or rare life is in the universe. Hell, we don't even know how common or rare life is in our own planetary system.

        Stop stubbornly trying to prove you were right by using convoluted semi-logic.
    • by keithmo (453716)
      Maybe they did, but their "smiley face" looks like a random collection of stars to us.
      • You're onto something there. Their smiley face would probably not be anthromorphic, as they probably don't look like humans. If I were a super advance civilization that could move stars and such, I would move black holes around me as to cloak my existence. If I have the power to move stars, there is a good chance that someone else does and could use it to blow me up.

        I say we start looking for constellations that resemble our imaginations of aliens. After that we look for black hole clusters and then wipe
        • Cloaking yourself with black holes may well end up drawing attention to you. It's a decidedly unnatural arrangement, the poles tend to spew X-rays, and even without that, a hole in space could well draw curiosity. I heard tell of stories of the early days of the Ohio-class boomers which were so quiet that the Soviets looked for dead spots in the water. It wasn't a perfect method, but it sometimes gave more clues as to the location than the US ever planned. Eventually, some method of combating this with
      • Re: (Score:2, Insightful)

        by ILuvRamen (1026668)
        well then they're dumb cuz just looking at the galaxy, it's not that hard to come up with a formation that would look incredibly unnatural. Like groups of stars forming the first couple prime numbers or a giant perfect circle that are 1/100 of a lightyear apart. Or even just a simple line of them spaced really close to each other and perfectly equidistant.
    • A space alien peering at us is a quaint idea. What does his ogling us accomplish? He can never reach the earth, and we cannot reach him in that neighboring galaxy.

      If we really want to explore the stars, we must focus on high-risk projects that bust the fundamental notions of science. One such project is the hyperdrive [newscientist.com]. Burkhardt Heim developed a unique (almost incomprehensible) field of physics. If he is right, then we can build a space ship to visit the space alien peering at us.

      Note that one dedu

    • by RAMMS+EIN (578166) on Saturday December 22, 2007 @08:00AM (#21789904) Homepage Journal
      ``Sometimes I think the surest sign that intelligent life exists elsewhere in
      the universe is that none of it has tried to contact us.''
      • ``Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.''
        Calvin, it's getting late. Time to come in!

        I can't Mom. I've got to kill snow goons!

    • by jc42 (318812)
      But you've got to wonder why some other super advanced civilization didn't move some stars around to circle themselves or something and make it really obvious where they lived.

      Because they don't consider where someone lives to be especially important. You don't know or care where I live, right? The important thing is the ability to communicate, and they do that simply by having the ubiquitous robot probes install gateways to the galactic network wherever they come across a world that has advanced sufficie
    • by Feanturi (99866)
      But you've got to wonder why some other super advanced civilization didn't move some stars around to circle themselves or something and make it really obvious where they lived.

      They just did, about 5 days ago. But we won't see the changes for several thousand years.
  • I, for one, would just wait for the Instructional Videos to arrive.
  • Shouldn't we have the same odds looking the other way? for all we know, we can be looking at an alien civilization that's looking at us right now. The problem is the planet renders to a single pixel. Good luck SETI.
    • All we need to do is get one of those really cool computer programs like they have on CSI where we can zoom in even further, enhance, and make out their continents...
    • Re: (Score:3, Insightful)

      by Bartab (233395)
      Exactly, which is why the occasional "SEE, NO OTHER EARTH LIKE PLANETS!!!" as proof for everything from "life is rare" to "ghod created us" are all silly noise.
  • by RobertM1968 (951074) on Saturday December 22, 2007 @12:49AM (#21788422) Homepage Journal
    The article makes a lot of assumptions such as:
    (1) Life on other planets has the same requirements for existence as us (Class M
            planet, water, air like ours, gravity like ours, etc)
    (2) Extra-terrestrials will be using technology similar to ours (as opposed to more advanced tech)
    (3) (Basing off #1 being true as they did) there are planets suitable for life such as ours that
            we haven't yet discovered that are looking in our direction.
    • by calebt3 (1098475)
      Class M [wikipedia.org]? Since when did we move to the Star Trek universe?
      • Well, I live in the Star Trek Universe quite often lately (check out http://www.startreknewvoyages.com/ [startreknewvoyages.com])...

        But, that aside, this IS Slashdot... I'm pretty sure every geek... I mean Slashdotter here knows what a Class M planet is... and if not, you just provided them with the necessary explanation ;-)

    • by Liquidrage (640463) on Saturday December 22, 2007 @01:24AM (#21788604)
      There's a lot to that discussion. We tend to assume that the laws of physics will work pretty much all over the galaxy. And in places where our current understandings break down, life isn't likely to exist (black holes, Planck scales, etc...).

      Given this assumption, there aren't a lot of options for different types of life. The chemistry just doesn't work. Biology is chemistry, chemistry is physics, and physics is mathematics. It basically puts in some ground rules for life. There's a decent little wiki on this: http://en.wikipedia.org/wiki/Alternative_biochemistry [wikipedia.org]

      As you can see in that wiki (there are pro's and con's for each of the alternates), based on our understanding life either does need most of the same things we do, or at least our biochemistry should be the most common in the universe. The math just makes it that way. There are some variables sure. And some alternatives. But for the most part, looking for stuff life us seems to most likely scenario.

      Now, given this, #1 and #2 should fall somewhat in line with what they're thinking. Sure, the minutia of evolution could lead to exotic live from our perspective. Something other then DNA based life even. But they (the aliens) should still come up with e=mc And their biochemistry should, at least, be something comparable to ours.
      • Given this assumption, there aren't a lot of options for different types of life. The chemistry just doesn't work. Biology is chemistry, chemistry is physics, and physics is mathematics. It basically puts in some ground rules for life.

        I'm no rocket surgeon, but this seems to me like an incredibly narcissistic set of assumptions.

        It took us thousands of years to get some basic grasp of how life on this planet works, and that's with a big head start - we have it right here to experiment with.

        Isn't it a bit

  • Welcome our galactic colonizing telescope-toting alien overlords!
  • oxygen, man (Score:5, Informative)

    by Quadraginta (902985) on Saturday December 22, 2007 @12:55AM (#21788454)
    Phoo, once you've detected O2 in the atmosphere, you're done. Only life could produce that much free oxidizer in a strongly reducing universe.
  • The earth throws off so much man made electromagnetic radiation that it would have to look like anomalous object. Now, how many of those do we see in 'near' interstellar space? None.
    • by gardyloo (512791)
      1/r^2, plus being near a far, FAR more powerful start will tend to do that.
    • by PPH (736903)
      Primitive civilization broadcasting megawatts into space in order to transmit a message a few dozen kilometers.

      Nothing to see here. Move along.

  • - been there, looked at it, nice place... and, looking at the primitive abundant upright walking livings there, quite funny what they do and how long they keep doing this. Quite amusing, actually. Looks they are on a turning point right now. Not sure if they self-destruct or get it together....
  • Hmm I wonder what that blue pixel is made out of. SEND IN THE ICE PIRATES!!
  • This assumes..... (Score:2, Insightful)

    by ezratrumpet (937206)
    ........that aliens see things the same way we do. What if they "hear" on the same spectrum that we "see"? We could what-if this to death, but it's important to remember that listening might be just as important as looking, and not just for SETI.
    • Interstellar sound waves...Brilliant!

      Now, how to go about building a giant concrete ear. Hmmm.....

      OK, honestly. Me thinks that anything that would produce sound waves that made it through interstellar space and was able to be detected on Earth would most likely be easier to detect looking for photons. Whether that be radio waves, visible, gamma, etc...

      Sound is just the movement of energy through matter in waves. While I have no doubt it's possible that in some alien world hearing would be more impo
    • Re: (Score:2, Insightful)

      by danilo.moret (997554)
      If they "hear" on the same spectrum that we "see" then just change the words, because to us they "see" but call it "hear". These words just label our senses, they don't define them. We label one way the sensors set to receive the "visible light" electromagnetic spectrum, they label it different. Big deal.

      Unless the label change also implies that the "audible electromagnetic spectrum sensors" don't dominate their senses as ours, it hardly matters what label gets used.

  • by brassman (112558) on Saturday December 22, 2007 @01:31AM (#21788636) Homepage
    "Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us."

  • by elgee (308600) on Saturday December 22, 2007 @01:36AM (#21788652)
    That ET will find us with a microscope.
  • Lightspeed is slow (Score:4, Insightful)

    by GeneralCC (1206630) on Saturday December 22, 2007 @01:37AM (#21788656)
    Well, if extraterrestrials were able to see earth using electromagnetic radiation (ie light, radio waves, ect) depending on their distance they would not see a modern earth. If they were over 5 billion light years away then if they looked at this solar system the Sun and the Earth would just be forming. This is because light speed is too slow. By the time the light reaches the extraterrestrials a large amount of time would have passed. They would have to use something other than a telescope to see a modern life sustaining Earth.
  • They would only be able to see Earth as a single pixel

    How about we launch some giant pixels so that they see more.

    It worked with Google push-pins [blogspot.com].
           
  • All they need is a smelloscope. If they can pick up the smell of cats, they'll find their way here.
  • This is a great line of inquiry and I certainly enjoy reading about such things, but wasn't the technical end of this "what if" scenario mapped out pretty extensively back in the 90s when the extrasolar planets started being detected? I'd be surprised if researchers are only just now getting around to asking cute generic "how could we directly detect earth-like planets by thinking like an alien measuring earth" brainstorming questions.
  • mind boggling (Score:2, Insightful)

    by sugarmotor (621907)
    It is mind boggling how limited these people's imagination is in regards to how other life could exist, see the universe, or interact with it. As far as I'm concerned life could exist within the sun itself. And then what use is a telescope??

    Nice day to you all!

    Stephan
  • 'They would only be able to see Earth as a single pixel, rather than resolving it to take a picture,' said Astronomer Eric Ford. 'But that could be enough for them to identify our planet as one that likely contains clouds and oceans of liquid water.'

    Wow. That's one hell of an information packed pixel. Maybe he means one of those spooky, hyperadvanced alien pixels. I hear they're super effective.

    If they are hostile aliens, we can only hope they do a lot of image processing. I hate to think the only thing sta
    • Re:pixelization (Score:5, Informative)

      by imsabbel (611519) on Saturday December 22, 2007 @05:04AM (#21789294)
      I see your humor, but...

      A single pixel can provide a hell of a lot of information: Do spectroscopy, and you can get the typical absorption lines (O2 for example should be easy to detect, and be a sure way for _anybody_ who detects it to tell something is odd about that planet).
      Track the intensity over time, and you can get the rotation period.

  • We already have the technology to image planets in other star systems, it's just that no one is willing to spend the money on it. By throwing enough money at the problem, we could already detect and analyze Earth-like worlds around other stars.

    So, if the aliens have our level of technology or better, and are willing go through the effort, they could easily find Earth.

  • by DavidD_CA (750156) on Saturday December 22, 2007 @06:07AM (#21789476) Homepage
    We've already been discovered, twice.

    The first time: they discussed us using irrelevant analogies, took a senseless poll, said things like "imagine a Beowulf cluster of these" and "itsatrap!", and one alien remarked "I, for one, welcome our new Earthling overlords."

    The second time: they just shouted "DUPE!" and moved on.
  • The article doesn't appear to mention at what distance they could detect us with a Hubble-like device, and so it doesn't really tell us anything seeing as we don't know how many sun-like stars are in that range.
  • ... what aliens, observing the electromagnetic patterns emitting from earth, would make of the odd modulo-7 component that derives from our 7 day week. It wouldn't seem to make much sense to them given that 7 does not divide evenly into a single orbit of the planet around the sun. Of course the 24 hour pattern the would also detect would align with the planet's rotation (pretty closely), so that would make the modulo-7 thing even more odd to them.
  • While there may be a high probability that there are Extraterrestrial Civilizations, the probability that they are now at the state of the Earth's 21st century development is extremely low. It is much more likely that they are far behind us or far ahead of us. If they are far ahead of us then the development of nanotechnology will allow them to build telesopes 100, 1000, 10,000 m in diameter with mirrors accurate to the atomic scale. They will be able to launch (or build) arrays of these in space. They
  • by wikinerd (809585) on Saturday December 22, 2007 @11:39AM (#21791328) Journal

    When I see Earth with Google Earth (by the way, FSF [fsf.org], where I am a member, has called the creation of a free compatible client a high-priority project [fsf.org], and if you have free time please try to help, and if you need hosting for your project I can give you [algolibre.org]), I hardly can detect life, let alone humans, on Earth. Visually it's very difficult to detect it (and nothing suggests that an alien would expect a green planet to be filled up with plants, in fact a scientist would expect plant life to be red-coloured and in fact that's how it was in the past as red-colour has greater absorption efficiency... Earth plants became green only after changes in the atmosphere). I can see, of course, that the planetary atmosphere is a very dynamic system (clouds go and come every day), but all the rest is nothing but white places over the poles (ice), vast blueness (oceans), a few greenie plains (jungles, where remained by the human effects), and some light brownish-yellowish regions (deserts). That's all. I would need to analyse the Earth's spectrum or possibly other means to find out what chemistry this funnily coloured vastness has.

    But wait, there's more: I can zoom in a little and see mountains etc. And if I zoom more I see that some oceans have little green islands in them, so perhaps I could start to understand that this bluish abyss could be some kind of liquid and the greenish spots could be areas of higher elevation. But still, it could very well be a dead planet with no life, let alone humans. So I have to zoom more. Oh, now I can see that there are some grayish spots near the greenery, as if someone had vomited on the Earth's plains. Yea, it certainly looks like vomit, but what is it? Zooming more... oh, it looks different from anything else, it has some kind of structure, lines etc. Still looking like vomit, though... structured vomit. Who the hell vomited on the planet we, the alien scientists, discovered? How can we write a paper on a vomited planet? Everyone will laugh, our academic reputation is at risk because of this vomit on this extra-Gliese planet.

    But let's move away from this freaking vomit and look closer at the green plains and the brownish-yellow regions to see what there is there to be seen. Zoom a bit... oh what's this? Some kind of lines in the desert? Oh, it looks like other aliens visited this dead planet earlier and played some earth games on it, eh? Perhaps they were having some kind of planetary football games or something and this was their soccer field... But wait, some lines are quite intriguing. Nah... these aren't lines, these are complete drawings. Let's move away a bit and zoom closer... Hm, here these look like symbols. Ok, there may once have been some intelligence on this planet, but now it must be dead, probably, as it is too far away from its star (we the aliens like hot stuff so we live near our star, and this is what we consider the only habitable zone possible, for us if it feels hot it's good and we believe the whole universe is somehow made for us to explore and play in, so any planet outside our habitable zone must be dead because that's what the big scientists here say).

    Where did this intelligence come from? Maybe it came from the vomit, so let's go back there and zoom more. Wow, what's that? It looks like the lines that divide the vomit in little rectangles have little ant-like things running over them. Oh, and by these lines there are big boxes. But what these boxes contain? Maybe there's more vomit in there! Ok, our scientists found the truth, these running things transfer the vomit from box to box! And maybe this vomit is intelligent! But not much, as it probably has not discovered telecommuting or work-from-home yet. And that's what we would expect from a planet outside the habitable zone, it must be so cold these (15-25C, which for us is too cold) that this vomit has its intelligence sabotaged by the tem

    • It's funny how I wrote all this vomit stuff and cockroach fiction while eating and am still able to safely finish my food
    • Forgot to add that if you really want to see how our planet looks like from the vastness of space, just fire up google earth in skygazing mode. Every pixel now is a whole world full of action, with many of them having other smaller worlds in orbit around them, and perhaps on some of these there are creatures like us calling their little pixel their home, and arguing, making love and war, playing with their gadgets (oh yeah there are surely geeks out there!), trying to find new theories of everything (surel

    • by imsabbel (611519)
      Maybe you should stup sniffing shit, because reading even half your post did only archive two things:
      a) a slight headache
      b) the feeling that there is somebody out there who's totally fucked up (and not me)
  • Seriously, any ET just needs a radio telescope and would hear all our transmissions, Jerry Springer, Oprah and even Riki Lake.

    No wonder we have not been visited yet!
  • Okay, so now suppose we have aliens that truly understand the value of a (ahem!) "manned" space presence and have built really large astronomical arrays.
  • I fear if they are, Charlie Pelligrino might have been right in The Killing Star http://sites.inka.de/mips/reviews/TheKillingStar.html [sites.inka.de]

    that is:Paraphrased from the book:

    1. Any species will place its own survival before that of a different species.
    2. Any species that has made it to the top on its planet of origin will be intelligent, alert, aggressive, and ruthless when necessary.
    3. They will assume that the first two rules apply to us.

    Add to this the facts of relativistic bombardment. A mi
  • We found you back in 1863.

    Soon you shall all die.

FORTRAN is a good example of a language which is easier to parse using ad hoc techniques. -- D. Gries [What's good about it? Ed.]

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