Professor Brian Cox reckons that at some point in the future people will be Martians.
The pop star-turned-physicist - born in Oldham - said Mars is the only planet that humans will be able to move to - and that it must happen as people cannot remain on Earth forever.
"It is actually the only place we can go beyond Earth," he said.
"In any plausible scenario, there is nowhere else that humans can go to begin their step outwards from the planet, other than Mars.
"If you think of the other planets, there's none of the others we can land on."
Cox, professor of particle physics in the School of Physics and Astronomy at the University of Manchester, added: "There may or not be Martians and we need to find out.
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"But there will be Martians, if we are to have a future.
"At some point we will be the Martians. That's clear to me.
"Because we can't stay here forever."
The Planets starts on BBC Two on May 28.
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