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Name: Missy
Status: other
Grade: other
Location: NY
Country: N/A
Date: 9/17/2005

Suppose astronomers wanted to send a message to an alien civilization that is living on a planet with an atmosphere very similar to that of Earth's. This message must travel through space, make it through the other planet's atmosphere, and be noticeable to the residents of that planet. What band of the electromagnetic spectrum might be best for this message, and why?

Someone already said radio waves, more specifically FM and TV waves and gave their reasoning. I totally agree with that persons answer. However, I am having a hard time now coming up with an answer of my own. Is there any other correct answers?

There is not a single simple answer to your question. An extra terrestrial civilization capable of attempting to make contact with Earth would have to contend with a number of problems similar to what the SETI project has to. Atmospheric transparency probably is not very important since they (or we) could send a message from a satellite in orbit above the atmosphere. Our "partner in space" would need to be closer than the age of the Earth because otherwise they would not know we even existed. This is a very liberal distance because it does not assume that the signal is the result of a "human intelligence", only that it is consistent with potential life.

A more restrictive limit would be only a couple of hundred light years. On the other hand, we might not be their only target. This would mean that the "Hello" message signal would have to be distinguishable by any conceivable civilization, otherwise, it would not be distinguishable from galactic "noise". What such a signal might be is an interesting question itself. The transmission frequency would have to be in a relatively noise-free region of the electromagnetic spectrum. It is also geo-centric to assume that such a civilization has not found a way to harness, let us say neutrino signals, which we Earthlings would have a difficult time identifying with current technology. I do not think there is a single "correct" answer to all the possibilities.

Vince Calder

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