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A wrote:
When was the first message sent by radio that would have made it through the ionosphere into outer space? I figure it must have been in the nineteenth century sometime. Or more specifically how many light years away is that first message now? That's a good question and almost impossible to answer with certainty. It depends on the transmission frequency, antenna configuration and the condition of the ionosphere at the time. Spark gap transmissions are rich in harmonics (many frequencies) so it's possible that some portion of a spark gap signal was able to pass through the ionosphere, most likely the higher frequencies. In that case it's been about a hundred years since we announced are presence to the universe. That would put the signal at 100-light years away, which includes more than two thousand stars in our region of the galaxie. However the chance of intelligent life on a planet orbiting one of those stars is extemely small, so it's not likely that anyone has received our first radio transmissions yet. I suppose you can't rule out the possiblility that someone passing by in their spaceship may have heard it. ;-) |
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