# Is broadcasting the location of Earth to potential extraterrestial civilization regulated?

How many times have we broadcast the location of Earth to the outer space? Are there any regulation in doing so?

I know so far we have send the Arecibo Message, and any receiver can trace the message sender's direction by the direction with which the message is received. But have we ever pin point our exact location of the galaxy and send it as a message?

• I recall the Voyager spacecraft had a fairly specific description of our location. And early TV signals were arguably interstellar because of the power in their signals. Though they likely lost cohesion before going that far. In modern times not many signals go out that aren't intentional. It is too inefficient on energy and money to send an unfocused signal that can go interstellar. As an aside, that's one possible explanation to the Fermi paradox: other civilizations naturally advance to a point where they emit few to no detectable signals. – zibadawa timmy Nov 16 '14 at 19:18
• Hmm. don't think this is an astronomy question. Perhaps better at space? – Walter Nov 17 '14 at 16:14

## 1 Answer

No, except in the sense that national broadcasting and so on is regulated. Our location can be fixed, as you suggest, from simply looking at where the signals come from.

Perhaps, though, you mean is it sent out "regularly" (i.e., at specified intervals). In truth we have been sending very powerful signals continuously into space since the dawn of the television age. Those signals may now start to wane in strength as we move to digital terrestrial television but that won't bother any aliens for some time yet.

• I was given the impression that location cannot be fixed from simply receiving a signal unless coordinates are given, or that two way communication happened as they have no way of knowing the distance. – user3685689 Nov 16 '14 at 20:55
• Yes, it's true you would not know the distance - but if you were "travelling" towards the signal you could judge that by the inverse square law, I suppose. – adrianmcmenamin Nov 16 '14 at 21:06
• Doesn't that require you to know the source power? – user3685689 Nov 16 '14 at 21:09
• Assuming our aliens were familiar with television broadcasts they could probably hazard a guess at that and, in any case I think the answer to your question is no, as you are measuring the ratio of the signal strengths received at two points, and that is merely dependent on $r^{-2}$ surely? – adrianmcmenamin Nov 16 '14 at 21:17
• If they were to watch the TV, they would soon find out (1) the coordinates and (2) that it's not worth to go there. – Walter Nov 17 '14 at 16:16