Over the course of this second season, we heard quite a bit from Seth Shostack.

He's a senior astronomer at the SETI Institute and the author of several books, including

Confessions of an Alien Hunter. He's made appearances on lots of TV shows and in movies, usually playing himself.

And he's the host of the SETI Institute's own podcast, Big Picture Science. In short, he's a busy man,

and one with a lot to say about science and the search for extraterrestrial life.

Since what you heard from him in the earlier episodes only touched on all the interesting things we talked about,

I wanted to give you the chance to hear the rest of the conversation, starting with an explanation of his chosen field, radio astronomy.

My background in astronomy is as a radio astronomer, and radio astronomers use, well, they're called telescopes.

They're called radio telescopes, but there's no eyepiece, there's no mirrors or no lenses. It's just a big, you know, metal antenna. And you sit inside a nicely temperature controlled room looking at computers.

And what's the advantage of radio astronomy over optical, I guess, would be the other option?

Yes.

Optical astronomy, you have radio astronomy.

Actually, you have many other kinds of astronomy.

There's x-ray astronomy, gamma-ray astronomy, now gravitational wave astronomy.

I mean, you know, anything that brings you information from the skies can be used.

But radio astronomy, which really developed just before the Second World War, allows you

to see the natural radio signals that are produced in space.

And we're not talking about aliens there.

We're talking about things like quasars and pulsars and hot gas and cold gas.

And it turns out all these things, some of them make light,

you know, stars make light. They don't make too much radio. But other things maybe don't make

too much light, but they make a lot of radio waves. And by studying those things, you can learn

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