Jump to content

92335031_Perseidsmeteorshowerbanner.jpg.f082cb58353bce3cc854fb958f76fc98.jpg

Will the Aliens hear our Radio and TV broadcasts ?


Recommended Posts

Ive often heard it said that our Radio and TV broadcasts could be picked up by "Aliens", so they could be listening to our planet long before they ever visit.

However, I have heard the radio broadcasts made by the Apollo missions and they were pretty low quality even though they were just on the moon.

I also fail to get radio stations in my car/home from far away places and thats just on our planet.

Now, I know our planet is round, radio waves may get blocked by hills, atmoshphere etc, but even so, I struggle to see them being powerfull enough to be picked up in our Solar System, let alone in another star system.

Would our broadcasts just be too faint, distorted and crowded out by noise pretty soon after leaving our solar system ?

Would they degrade over distance ?

Just how many star systems would they have reached given the first commercial radio broadcasts started in the 1920's ?

Link to comment
Share on other sites

Radio listeners in the region of Aldeberan will be tuning in to BBC World Service coverage of WW2. I'm sure the signal will get that far because back then they used thumping great transmitters at various frequencies.

These days, many of our transmissions are more discrete. As the radio spectrum becomes more congested there are far fewer big powerful transmitters.

So rather than have a few broadcasts that were very prominent we now produce more of a low key cackle of digital and analogue signals that are directed to their audience more accurately. Probable less penetrating to interstellar space.

Link to comment
Share on other sites

It's highly unlikely. Any intelligent life would need to be looking (or listening ) in exactly the right place and the signals would be extremely weak (inverse square law) and probably fragmented. Our nearest star other than the Sun is Proxima Centauri at 14 million light years and the huge distances mean the odds of pinpointing and receiving a signal are minscule.

Link to comment
Share on other sites

Radio wave intensity falls off with inverse square law, so every doubling of distance it is 1/4 the power.

However that said, if they are anything like us, they will have very powerful radio telescopes aimed at detecting faint signals.

This page http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980123d.html lists some stats and estimates 14,600 stars within 100 light years (roughly the time above).

Link to comment
Share on other sites

Good artical - poor result thought:

Shostak calculates that Nasa's recent broadcast of Beatles music towards Polaris, the North Star, using a 210ft antenna and 20kW of power, would require any potential aliens to have an antenna seven miles across to be aware of it. To actually receive it as music, this would need to be increased to a 500-mile wide antenna. Polaris is 430 light years away.

So basically we are not likely to be heard or seen.

Thats a shame.

Link to comment
Share on other sites

The easiest signals from us they could probably receive are our RADAR pulses from things like ships, aircraft, space RADAR etc, they tend to be very well concentrated into narrow beams and are many kilowatts focused by parabolic reflectors (maybe mega watts ERP) and swept right across the horizon 24/7.

Link to comment
Share on other sites

Shostak calculates that Nasa's recent broadcast of Beatles music towards Polaris, the North Star, using a 210ft antenna and 20kW of power, would require any potential aliens to have an antenna seven miles across to be aware of it. To actually receive it as music, this would need to be increased to a 500-mile wide antenna. Polaris is 430 light years away.

I would imagine for any 'advanced' civilizations out there that really do want to find others (as we do) then I would have thought it a simple matter for them to build radio antennas (or the equivalent of) many miles across that orbit their own star or such like. I don't think it would be hard for them to do if they had really got the hang of moving about their own solar system with ease, their's more than enough materials available in any solar system.

Link to comment
Share on other sites

I would imagine for any 'advanced' civilizations out there that really do want to find others (as we do) then I would have thought it a simple matter for them to build radio antennas (or the equivalent of) many miles across that orbit their own star or such like. I don't think it would be hard for them to do if they had really got the hang of moving about their own solar system with ease, their's more than enough materials available in any solar system.

Yes but they would need to be looking at exactly the right point in space which the odds of probability say would be nearly impossible, unless they already knew we were here.

Link to comment
Share on other sites

Well, personally I greatly suspect their are far more efficient ways to communicate across vast distances that we no doubt can't even imagine as yet. It's only been very recent that we have discovered and almost mastered radio communication.

Edited by Cath
Link to comment
Share on other sites

The easiest signals from us they could probably receive are our RADAR pulses from things like ships, aircraft, space RADAR etc, they tend to be very well concentrated into narrow beams and are many kilowatts focused by parabolic reflectors (maybe mega watts ERP) and swept right across the horizon 24/7.

The ships I sailed on had 60KW 'S' band radars. Their ERP was about 12 watts as they were pulsed.

Link to comment
Share on other sites

Yes but they would need to be looking at exactly the right point in space which the odds of probability say would be nearly impossible, unless they already knew we were here.

I suppose they could build as many as they like, could build a whole ring of them (many 1000's of receivers/antennas) in an orbit centered around their planet(s) or sun.

Link to comment
Share on other sites

The average power would be low but the pulses themselves would be very high ERP.

The energy content of the pulse is equal to the peak (maximum) power level of the pulse but as the measurement is over a longer period than the pulse duration it's referred to as average power.

Link to comment
Share on other sites

It's highly unlikely. Any intelligent life would need to be looking (or listening ) in exactly the right place and the signals would be extremely weak (inverse square law) and probably fragmented. Our nearest star other than the Sun is Proxima Centauri at 14 million light years and the huge distances mean the odds of pinpointing and receiving a signal are minscule.

A bit nearer, I think. 4.24 LY or so? Not that it matters much.

The real issue, I think, is that intelligence can mean something entirely different from what we think it means. Hollywood loves to make little creatures just like us but with pointed ears and green skin - who might have some notion of what World War Two was all about. However, an entirely different kind of intelligence might not interact with our kind of intelligence at all. Genetically my dog and I parted company no more than a few seconds ago in the greater scheme of things, having shared a common ancestor. We are almost the same creature. Four legs, two eyes, two ears, a skeleton with broadly the same structure and pentadactyl limbs. But what does she know of World War Two? And what is worth knowing about it, for that matter? Apart from the fact that humans orchestrated it with their phenomenal intelligence.

Olly

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.