Could An ExtraTerrestrial Find Earth with a Telescope?

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."

I've got an idea

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.

Re:I've got an idea

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

Well then, screw them... I mean, if they aren't going to follow the stinking RFC standards about smilies and emoticons [rfc.net] then why do we even want their standards-breaking butts here anyway?

Intergalactic quarantine symbol

Rings around a gas giant means "keep the hell away from this system and don't, whatever you do, let the inhabitants get out".

A pentagon-shaped smiley?

Whoa - if their smiley were pentagon-shaped I'd definitely run! Other civilizations with pentagon-shaped things aren't famous for being friendly towards people who are "different".

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What the hell. Most of the Wiccans I've met are perfectly ok people. Wierd, but nice.

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Wiccan wear Pentacles and use ritual Pantacles.

Pentagons are a sound dig at the Pentagon of the USA.

Re:I've got an idea

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.)

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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

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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.

Re:I've got an idea

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.

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It's only been about 100 years since Marconi invented the radiotelegraph. Even if we assume that they would be 100% certain to pick up any signal we've sent, no matter how weak, and that they would be 100% able to recognize it as carrying meaning, any civ

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The other way to look at this is that it would take 100 years for signals emitted from within this (mostly empty) 100 light-year sphere to get here.

If we extend it to 1000 LY in order to increase our chances, that means that any signal we get now is from a

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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 argum

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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 "Eavesdr

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This has nothing to do with bible school, but a simple knowledge about rudimentary statistics.

The there is life on OUR planet (by itself) says absolutely nothing about an increased chance it would be on other planets. For the simple reason - in the hypothe

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Maybe they did, but their "smiley face" looks like a random collection of stars to us.

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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.

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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 day

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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

A Space Ship to Visit the Space Alien

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

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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 b

Re:I've got an idea

``Sometimes I think the surest sign that intelligent life exists elsewhere in
the universe is that none of it has tried to contact us.''

Too much work....

I, for one, would just wait for the Instructional Videos to arrive.

Too many assumptions?

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.

Re:Too many assumptions?

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.

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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 pr

oxygen, man

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.

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Indeed. That's what started James Lovelock [wikipedia.org] down the road to the Gaia hypothesis [wikipedia.org].

Omygod

- 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 th

This assumes.....

........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.

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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

Do we want to be found?

"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."

And then there is the possibility

That ET will find us with a microscope.

Lightspeed is slow

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.

Simple!

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].

They don't need to see us

All they need is a smelloscope. If they can pick up the smell of cats, they'll find their way here.

only just starting to brainstorm in 2007?

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

mind boggling

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

pixelization

'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. T

Re:pixelization

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.

What a pointless question.

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

We've Already Been Discovered

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.

Google Earth is your friend..DRMed, but still good

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

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1/r^2, plus being near a far, FAR more powerful start will tend to do that.

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Primitive civilization broadcasting megawatts into space in order to transmit a message a few dozen kilometers.

Nothing to see here. Move along.

Single pixel? Not a problem...

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...

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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.

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It never ceases to amaze me how people always think that, if there is life out there, it isn't as limited as we are by the laws of physics.

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actually I am going to have to second gpp here. think for just a moment about the vision of an eagle compared to ours. their vision is developed similarly to ours only with more "sensors". I've never even seen any indication that eagles are at the high end