In part three of The Great Exoplanet Debate, the panel of experts discusses our broadening view of the ‘habitable zone’ around different star types, and our preconceptions of what makes a ‘habitable environment.’ On topic that is covered is the idea of viewing the early Earth, from which we have geological evidence that we can study, as an ‘alien’ world. The early Earth was much different than the planet we’re familiar with today, but it was still habitable for life as we know it.

The transcript of the plenary session is now available at: http://www.astrobio.net/debate/5395/the-great-exoplanet-debate-part-3-limits-to-determining-habitability . A video of the plenary session is also available at: https://connect.arc.nasa.gov/p68qflmgnhk/?launcher=false&fcsContent=true&pbMode=normal