A Moment of Science

Is E.T. Trying to Phone?

If E.T. does try to phone us how will we know it? Find out on this Moment of Science.

If E.T. does try to phone us how will we know it? Find out on this Moment of Science.

I was listening to the radio last night, and at first everything was all static-y, and then I heard this “whoo oooo ooo noise”. For a moment, I thought it might be aliens, but it was just some guy singing opera. Still, it got me wondering–how will scientists listening for a transmission from outer space know that they’ve actually picked up a signal?

Well, according to the SETI institute, which helps coordinate the search for extra- terrestrial life, most radio experiments that look for transmissions from outer space focus on what are known as “narrow-band” transmissions. The big assumption here is that any extraterrestrials sending out a transmission are decent engineers, and so they’d send out a focused signal that doesn’t take up a lot of bandwidth.

Think about how radio signals operate. You know that electromagnetic waves have certain frequencies, and that when you listen to your public radio station, you’re tuning a specific frequency so you can pick up a specific signal.

Well, in contrast, electromagnetic waves that are generated by natural phenomena like pulsars and quasars occur over a broad range in the spectrum, and not just at a narrow frequency. So they show up, so to speak, like static all over the radio dial. Therefore, scientists assume that if a transmission only uses up a small part of the spectrum, it must be artificially generated.

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