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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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  • Re:I've got an idea (Score:5, Interesting)

    by AKAImBatman (238306) <akaimbatman@gmai[ ]om ['l.c' in gap]> on Saturday December 22, 2007 @01:53AM (#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.)
  • by reporter (666905) on Saturday December 22, 2007 @02:10AM (#21788532) Homepage
    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 deduction from Heim's work is a formula for calculating the mass of fundamental particles. The formula has been subjected to review by esteemed physicists and is 100% accurate. Could the hyperdrive be another valid consequence of Heim's work? The possibilities are quite tantalizing.

    "To boldly go where no one has gone before ..."

  • by elgee (308600) on Saturday December 22, 2007 @02:36AM (#21788652)
    That ET will find us with a microscope.
  • Re:I've got an idea (Score:5, Interesting)

    by AKAImBatman (238306) <akaimbatman@gmai[ ]om ['l.c' in gap]> on Saturday December 22, 2007 @03:21AM (#21788784) Homepage Journal

    Um, they told you that in bible school, right?

    No, basic scientific principles told me this. While the Drake Equation [wikipedia.org] is not accepted by all scientists as a valid computation, the Fermi Paradox [wikipedia.org] is still a difficult problem to solve.

    We are not so special. There are 10^21 stars out there - there must be many civilizations out there.

    To throw an equally unfounded accusation back at you, you're a fan of Carl Sagan, right?

    Let me put this in simple terms: The size of the universe is known to be at least 93 billion light years across, and is estimated to be ~13.7 billion years old. In a universe that big and that old, there is a strong chance that any other civilization(s) that may have formed are extremely far apart from one another. So far apart that there is a good chance that the civilization(s) will "miss" each other's existence.

    Like it or not, if there was a civilization coexisting in our neck of our galaxy, we'd have some inkling of it already. Unnatural radio transmissions would stand out against the background radiation and give us a sense that another civilization is there. We have been scanning the skies with powerful equipment and so far have come up with little to no evidence of such transmissions.

    The long and short of it is that from what we know today, there's an infinitesimal chance that we humans will ever meet another civilization. The best we can hope for is that we find planets that support more basic forms of life.
  • by Free_Meson (706323) on Saturday December 22, 2007 @04:25AM (#21789068)
    The kind of "visit" an alien intelligence would pay us would be most unwelcome.

    No civilization is crossing the vast emptiness of space for any reason other than settlement. The investment of resources required for such a journey would be too massive to be undertaken for any other reason.
  • Re:I've got an idea (Score:2, Interesting)

    by thief_inc (466143) on Saturday December 22, 2007 @01:02PM (#21791470) Homepage
    If we assume that there are 1000's or even millions of civilizations out there at different stages of development and a different distances from the earth we should receive transmissions eventually. Follow me for a second.
    Imagine a civ that is on a parallel development track as us but they are 2000 LY(light years) from us. We won't receive their transmissions for another 2000 years. They would have to be 2000 years ahead of for us to receive their transmissions. If the universe does support a variety of civilizations we should eventually receive a transmission sometime of the course of a 100 year period. Also even if there are civilizations a million years more advanced than us as long as they are a million light years away we would have received their transmissions. Of course we are kind of threading the needle here but if the universe is abundant in life forms than we should have transmissions from somewhere by now or at least in the next 100 years or so.

    If we don't find a transmission in my lifetime I will have to come to the conclusion that life is in fact rare in the universe. And if there is other civilizations out there they are so rare that it may be many 1000's if not millions of years before we make contact, if ever we just may miss each other in the end.

  • Re:I've got an idea (Score:3, Interesting)

    by Xonstantine (947614) on Saturday December 22, 2007 @02:06PM (#21791904)

    This is an ignorant argument
    Actually, not it isn't.

    Absence of evidence is not evidence of absence.
    Um, yeah it is. Particularly when you are looking for evidence. Said another way, your argument can be applied to argue that there might be invisible pink elephants flying overhead. Which is to say, it's useless and not an argument at all.

    There are a couple of solutions to the lack of evidence problem, but the most probable one is that there simply is not technological life besides us within our visible light cone. Like another poster said, the Fermi paradox is basically insurmountable. If there was advanced technological life in the galaxy, they would be here (and everywhere else) by now. The fact that they aren't strongly suggests that we're it.
  • Re:I've got an idea (Score:3, Interesting)

    by jc42 (318812) on Saturday December 22, 2007 @06:00PM (#21793330) Homepage Journal
    Typical radio transmissions virtually disappear well short of a single light year. And by "virtually" I mean our own giant radio antennas wouldn't hear them.

    Not true at all. Back in 1978, Science published an article on the topic [sciencemag.org]. Its title was "Eavesdropping: The Radio Signature of the Earth". If you're not a subscriber, you can find several copies of it online, as well as several other articles that cite it and do further analysis. The authors studied what could be learned about our planet by an astronomer with our level of technology (as of 1978) living on a planet within the sphere of roughly 50 light-years that our broadcasts had reached. They assumed that no program content could be deciphered by the remote astronomer, and only the Earth's changing spectrum over time could be measured.

    Their conclusions were fairly impressive. They started by explaining the nature of the received signals, and how those could be used to determine our planet's orbit, its day length, the orbit of our large moon, and the rough temperature zone in which we live.

    They went on to point out that our radio broadcasts are mostly done with hardware that puts its energy into a narrow frequency band, and mostly horizontal to the surface, so that from a remote viewpoint each broadcast station would appear briefly and fade. That is, the radio spectrum received from the Earth would come mostly from the limb, and not from the disk. This could be used to draw a map of the broadcast stations. The Doppler shift of each station as it appears 12 hours apart on opposite sides would give the station's latitude, the time would give its longitude. The resulting distribution would show that there are two different kinds of surface on our planet, and we live mostly on one of them (and mostly along the boundaries). Knowing the planet's temperature zone would tell the astronomers that we're on a water world, and our stations are on land.

    As the stations' frequencies drift over the year, it would become clear that we are diurnal, and also active during the evening, but not active between midnight and dawn. Further analysis of the signals would show the use of several different kinds of hardware, and these are distributed in patches over the planet. This shows our ability to organize on a large scale, but not on a planetary scale. The use of the same broadcast hardware in different areas would show our ability to form distant alliances between our "nations".

    Anyway, the article was an interesting illustration of what our broadcasts have been telling to any distant astronomers with technology as good as ours. They left it to the readers' imagination what could be deduced by more advanced astronomers. And, of course, our signals have propagated another 30 light years since then.

"Everything should be made as simple as possible, but not simpler." -- Albert Einstein

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