Exterrestrials watching earth TV

[Salty25]

I was just reading up on the Voyager mission - as you do - and it occurred to me whilst reading about the 'golden disc' that we've been sending out television and radios signal for at least a century or more now.

how far into our broadcasting could the closest possible exterrestrial civilization have got, the 1920's, 30's? its an odd thought they could be bootlegging Sky and Art to watch the footie soon !

 

[2cvbloke]

Makes me think of that episode of Futurama where the aliens from Omicron Persiei 8 come to earth cos of something happening a millenium ago....

 

[Channel Hopper]

It would be nice to think that any intelligent life that is within 100 light years and sufficient receiving technology could have been watching our satellite broadcasts, but I fear not.

It was mentioned in the film Contact, that the power of the Berlin Olympic transmissions using relatively low frequency VHF were of a magnitude that may have been picked up elsewhere without too much difficulty.

The use of satellite uplinks since the mid 70s does give a far more focused beam of signal, and a star system within 30 light years or so, which happens to be inline with geostionary satellites and the uplink station, could well have programme content for a fleeting microsecond as the Earth and satellite move in relation to the sky, but its unlikely they would get anything that makes them want to spend time in piecing together potential content, even if it reappeared on a daily basis. (especially if it was a shopping channel)

 

[Analoguesat]

Hope they got sensitive equipment - the power decreases with the square of the distance, so if you double the distance the power drops to a quarter....

 

[Channel Hopper]

or they could already be here ...........

 

[spiney]

http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html .

Satellite tv is not receivable much beyond the earth.

 

[Channel Hopper]

http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html .

Satellite tv is not receivable much beyond the earth.

Inetesting to note that only frequencies below 2.4 GHz are on the chart, and that a 22TW S band signal (allegedly) gets 720 light years out.

Do you have any propogation data for the 11 - 30 GHz group of microwave signals ?

 

[Salty25]

its a nice dream nonetheless, although i cant imagine theyd be too pleased if they came to earth to find out if there was a third series of Faulty Towers.

 

[spiney]

In free space, all radio frequencies will - of course - propogate equally well!

DIfficulties are various absorbtions in the earth's atmosphere, then - once outside that - in interstellar space, where there's vast amounts of molecular and ionised hygrogen. Although maybe just 1 particle per cubic meter (!), over astromnomical distances that comes to a lot of stuff!

What the excitation modes of these clouds are, I don't know offhand but a lot will be in microwaves region (translational/rotational modes), no doubt various SETI and other (microwave spectroscopy) websites list the frequencies.