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Could An ExtraTerrestrial Find Earth with a Telescope?
Posted by
Zonk
on Sat Dec 22, 2007 01:38 AM
from the helloooo-up-there dept.
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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I've got an idea (Score:4, Funny)
Re:I've got an idea (Score:5, Funny)
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Re:I've got an idea (Score:4, Funny)
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Intergalactic quarantine symbol (Score:5, Funny)
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A pentagon-shaped smiley? (Score:3, Funny)
Re: (Score:3, Informative)
Re:I've got an idea (Score:5, Interesting)
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.)
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Re:I've got an idea (Score:5, Interesting)
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.
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.
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Re: (Score:3, Informative)
Re: (Score:3, Interesting)
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 insu
Re: (Score:3, Interesting)
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 astro
A Space Ship to Visit the Space Alien (Score:3, Interesting)
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
Re: (Score:3, Interesting)
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:4, Insightful)
the universe is that none of it has tried to contact us.''
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Too much work.... (Score:2)
Too many assumptions? (Score:5, Insightful)
(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.
Re:Too many assumptions? (Score:5, Informative)
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.
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oxygen, man (Score:5, Informative)
Do we want to be found? (Score:4, Insightful)
And then there is the possibility (Score:5, Interesting)
Lightspeed is slow (Score:4, Insightful)
We've Already Been Discovered (Score:5, Funny)
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.
Google Earth is your friend..DRMed, but still good (Score:3, Insightful)
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
Re: (Score:3, Insightful)
Re:pixelization (Score:5, Informative)
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.
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