The Royal Institution Annual Christmas Lectures to Young People.
6: Planetary Systems Beyond the Sun
Professor Carl Sagan is perhaps the world's greatest optimist for the existence of intelligent life elsewhere in the Universe. In this last lecture of the series, he explains what an immense and difficult task it is to find, and communicate with, alien intelligence; but what earth-shaking significance such contact would have for mankind. The search may be fruitless until well beyond the lifetimes of his young audience - but SAGAN urges the next generation not to abandon it.