Are we alone? It's the oldest question we have, and for the first time in history we have instruments capable of actually answering it. We look at where life might be hiding in our own solar system, how astronomers hunt for biosignatures on planets trillions of kilometres away, and why the definition of life turns out to be surprisingly slippery.

You'll come away understanding what extremophiles taught us about where life can survive, why Europa and Enceladus matter more than Mars for this question, and how we could detect life without ever seeing it.

Talking Science is sponsored by Kinsoft. Visit www.kinsoft.com.au

Further reading: NASA Astrobiology Institute; SETI Institute research pages; ESA astrobiology resources.