This evening’s talk was given by Chris Lintott, familiar to many as co-presenter of the BBC TV programme The Sky at Night. His talk, with the title “Who, What and When?“ was an animated and enthusiastic run-through of progress in our understanding of the Universe and our place in it. He began with “When?“, starting with Olber’s Paradox, and leading through events such as the discovery of red-shifted galaxies and of the cosmic microwave background to our current understanding of the expanding universe which started 13.7 billion years ago. Moving on to “What?“, he then explained how the structure of the Universe, with its many clusters of galaxies, requires not just ordinary matter, but dark matter and dark energy as well. Finally, for “Who?”, he took the Drake equation, and showed us just how far we’ve got in determining whether we’re alone in the Universe.