Mystery #4Tier 2listening for aliens

If aliens existed, how could we possibly hear them across space?

Space is unimaginably huge, and even the nearest star is more than four years away at the speed of light. We cannot just pop over for a look, and we certainly cannot shout that far. Yet scientists really do try to listen for signs of alien life. If aliens were out there, how on Earth could we ever hear them?

A row of radio dishes standing in scrubland under a grey sky, all tilted at the same patch of the heavens, listening — Photo: brewbooks · CC BY-SA 4.0 · via Wikimedia Commons

Your guess

If a faraway civilisation wanted to reach us, what might we be able to catch here on Earth?

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