Could An ExtraTerrestrial Find Earth with a Telescope? 179
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."
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.
This assumes..... (Score:2, Insightful)
Re:I've got an idea (Score:2, Insightful)
Do we want to be found? (Score:4, Insightful)
Lightspeed is slow (Score:4, Insightful)
mind boggling (Score:2, Insightful)
Nice day to you all!
Stephan
Re:I've got an idea (Score:2, Insightful)
If we extend it to 1000 LY in order to increase our chances, that means that any signal we get now is from a civilization 1000 years ago -- which is now 1000 years more advanced than when they sent that signal. Assuming they will receive
To sum up, either we have to be really, really lucky to find aliens "nearby" who haven't figured out how to stay quiet, or, the aliens are so far away that we might be luckiest if they don't find us.
Re:Doesn't that mean.... (Score:3, Insightful)
Re:I've got an idea (Score:4, Insightful)
the universe is that none of it has tried to contact us.''
Re:This assumes..... (Score:2, Insightful)
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.
Re:I've got an idea (Score:2, Insightful)
This is an ignorant argument http://en.wikipedia.org/wiki/Argument_from_ignorance [wikipedia.org]. Absence of evidence is not evidence of absence. Perhaps radio communication is not as ubiquitous as we believe it to be.
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