If aliens are sending us signals, are we set up to detect them? Dan Riskin speaks with planetary scientists, radio astronomers, and computer scientists who explain how the search for ET has ramped up in the last few decades. But if they're successful, is there a way to predict what alien creatures might look like?

THE SOUND OF ET - We collect sounds from space all the time in the form of radio waves. For example, the farthest spacecraft from Earth, Voyager-1, sent back some haunting signals as it crossed from our sun’s solar system out into interstellar space. But those same electronic ears built to listen for human-made signals, might someday hear sounds sent by someone else.

On April 29, 2019, the Parkes Radio Telescope in Australia was pointed at the star closest to our own sun, Proxima Centauri, when it picked up a strange signal. It was a pure tone at 982.02 MHz. We know there’s a planet orbiting that star. Might aliens on that planet have sent the signal? How would we know?

Daniel Wertheimer, an astronomer from the University of California Berkeley, has been scanning radio waves for decades. W5 asked him what he listens for. “When we point our telescopes anywhere in the sky, what we receive sounds like hissing noise (from galaxies and the big bang radiation). It sounds like when you tune your radio TV between channels. If ET were transmitting, we'd still get the hissing noise from the galaxies and big bang, but also might hear a very faint whistle.”

THE SIGHT OF ET - Another big question is what those aliens, if they exist, might look like. To get an informed guess, W5 turned to a scientist whose work doesn’t involve telescopes at all - Roger Hanlon studies octopuses.

From our human perspective, it’s hard to find anything on Earth more alien than an octopus. They have no bones. They can change the colour and texture of their skin. And their bodies change shape like flexible water balloons – even an impressively large octoppus can squeeze its body through a hole just a few inches wide. Their eyes don’t see colour, but they can detect the polarization of light, something totally invisible to us. They have nine brains – a big central one, and a smaller one in each arm. The list goes on. “We often talk about… octopus as aliens from inner-space,” Hanlon tells W5. “Inner-space being the ocean. And they really are. They're alien even relative to other animals that live in the ocean. They are just so different.”

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