Jill Tarter: The habitable zone is a pretty simplistic concept. And that’s all we can do at the moment.

That’s astronomer Jill Tarter, director of The Center for SETI Research – the search for extraterrestrial intelligence. As scientists seek life beyond Earth, they’re eyeing planets like our own in the habitable zones of distant stars.

Jill Tarter: It’s our Goldilocks story. You get too close to the star, it’s too hot. You get too far away, it’s too cold. But there’s a region where it’s just right, and you can imagine having liquid water on the surface. And that’s to first-order what the habitable zone is.

Tarter said we might find life beyond a star’s habitable zone.

Jill Tarter: We’re realizing that the satellite of Jupiter, Europa, probably has twice as much water, brine, as all the oceans on the Earth. And it’s been there, under ice, for 4.5 billion years. And there’s liquid water, goodness. Maybe there’s life there.

And that’s surprising because Europa has no known liquid water on its surface.

Jill Tarter: When I use radio telescopes to try and find evidence of someone else’s technology, an intelligent species, machines transmitting, I can bypass all that. Because I find the technology, and then I infer the intelligent technologists, and then we go looking for where that signal might be coming from.

Earth & Sky asked Tarter what contact with life out there might be like.

Jill Tarter: I expect to be surprised. Nature has been far more inventive than astronomers ever have been.

Our thanks to:
Jill Tarter
Director
The Center for SETI Research
The SETI Institute
Mountain View, California