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Thread: How many stars/planets did our radio signals reach yet? [ALIENS]

  1. #1 How many stars/planets did our radio signals reach yet? [ALIENS] 
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    Sorry for adding aliens to the title, I just thought it'd bring more views and posts

    From what I hear, first TV signals broadcasting unintentionnaly to the universe at the speed of light started in the late 40's, so we're talking about a sphere around earth of roughly 60-70 lightyears of radius of stars and planets getting signalled that "intelligent" life is here on earth. Obviously, I put intelligent in quotations marks as any alien species watching our 50's TV would probably be appaled by the content

    We're also getting more confident on the odds of earthlike planets being in the habitable zone. I don't know the probability but I suppose our signals must already have reach a ton of habitable planets right now. Can you guys make some estimates?

    Now odds of intelligent life is certainly harder to guess at, but if any happened, they're likely far in our technological future (if they didn't kill themselves of course), and possibly reached faster than light travel already. Then again, such civilization probably would have detectors spread out all around, so our signals doesn't even have to reach their planet to be aware of us I guess. My point is, if they care enough to come, we could get a visit shortly after they become aware of us, right? As for contact if it happened, I currently find myself in the optimistic camp, because as Arthur Clarke said "Advanced malevolent alien species would probably blow themselves up".

    I don't know, i may be rambling back on the Drake equation, I'm tired, but I just feel as if this possibility, contact that is, is actually likely to happen before we as a species are able to move out of our solar system, and that this sphere of radio signals is a very important time and space scale to keep in mind.

    What do you guys think?


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    Hey 6AM-Ximlab, apparently you're not very good at subliminal marketing of your posts Sorry


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    Quote Originally Posted by Ximlab View Post
    Hey 6AM-Ximlab, apparently you're not very good at subliminal marketing of your posts Sorry
    wait somebody will reply. i have no idea about this.
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    Life-Size Nanoputian Flick Montana's Avatar
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    Ximlab likes this.
    "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
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    that graphic really puts it into perspective, Flick. we're soooooo insignificant.

    Sometimes it is better not knowing than having an answer that may be wrong.
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    Nice picture.

    Btw, offtopic question : Are we in stable orbit of milky way or being sucked down the center of this "cyclone" at such slow speed it ll take billions of years?
    If you can't explain it simply, you don't understand it well enough.
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    Quote Originally Posted by Ximlab View Post
    Nice picture.

    Btw, offtopic question : Are we in stable orbit of milky way or being sucked down the center of this "cyclone" at such slow speed it ll take billions of years?
    Stable orbit. The spiral arm shapes represent pressure waves traveling through the galaxy. These pressure waves help instigate star births. They are brighter because they have a higher number of bright stars. The brighter the star, the shorter its lifespan, so you are going to see more of them in regions of higher star birth rates. The darker regions don't create new stars to make up for the bright stars that have burned out, and have a population mostly of older stars. These longer lived stars also are dimmer.
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    Going back to original question. I stumbled in my search on an old (1998) post, not sure of its accuracy.
    http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980123d.html

    I
    t says in a 100 light year radius sphere, there's about 15000 stars.
    I'm going to very lazily avoid the maths and estimate a 60 LY radius would hold 8000 stars.

    And this quote, estimate 15% of these stars hold habitable zone earthish planets.
    "Citing Michel Mayor’s Geneva team, which found that roughly 30 percent (give or take 10%) of F, G and K-class stars have super-Earth or Neptune-mass planets, Kipping narrows the field yet again:"
    "
    Using 30% as a fixed value and assuming that very roughly half of this sample correspond to rocky planets and half to Neptune-like gas giants then we may write down that 15% of all F, G and K-type stars have rocky planets around them. It should be noted that this value is very likely an underestimate due to fact planets of Earth mass are currently below the detection threshold."

    We're still talking on this very rough (lowballed it) estimate about 1200 planets already in our "radio sphere", growing each year by a higher volume. It's not too shabby, but I guess it's not overwhelming, lower than I was expecting to find.

    Gives me a sense of volume and density of our galactic neighborhood already. That's something!
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