Astronomy is the most universal of all the sciences: all humans, throughout history, have looked up in wonder at the stars. Huge telescopes extend our vision a million times further than the unaided eye; space-probes have travelled to all the planets of our Solar System. Modern astronomy reveals a far more varied and intricate cosmos than our forbears could have envisaged. In the last decade we've learnt that most stars are orbited by retinues of planets, just as our Sun is. Indeed our Galaxy harbours billions of planets, many the size of the Earth. Could there be life on any of them? Even intelligent life? And will human (or post-human) life from Earth ever voyage to distant stars? These issues are now within the remit of science – no longer just science fiction. This illustrated lecture, intended for a general audience, will emphasise what we have learnt and how much mystery still remains. It will aim to show how these discveries help us to understand our own special planet, and its biosphere, in a deeper cosmic context.

Martin Rees is Astronomer Royal, and a Fellow of Trinity College Cambridge (of which he was Master during the period 2004-12). He is also Visiting Professor at Imperial College London. After studying at Cambridge, he held post-doctoral positions in the UK and the USA, before becoming a professor at Sussex University, and subsequently Plumian Professor of Astronomy and Experimental Philosophy at Cambridge, where he also served for ten years as director of the Institute of Astronomy. From 1992 to 2003 he was a Royal Society Research Professor. He is the author or co-author of more than 500 research papers, mainly on astrophysics and cosmology, as well as seven books, and numerous articles on scientific and general subjects. He has lectured widely, been on many advisory groups, and received numerous international awards including the Balzan Prize, the Crafoord Prize and the Templeton Prize. He is a foreign associate of the US National Academy of Sciences, the Russian Academy of Sciences, and several other foreign academies. He was knighted in 1992 and in 2007 became one of the 24 holders of the Order of Merit, a special honour awarded by HM The Queen. He served during 2005-2010 as President of the Royal Society and in 2005 he was appointed to the House of Lords.