Light echoes are reflections of light from distant objects in space. But what do they look like and how can they best be seen? Sir Patrick Moore and his guests Professor Mike Bode and Dr Tim O'Brien explain all. Chris Lintott helps to construct a new radio telescope in Hampshire, while Pete Lawrence and Paul Abel preview what is on view in the October skies.

Ursa Major, the Great Bear, is a rich source of galaxies, double and variable stars and the Hubble Deep Field, through which we are able to look back 10 billion years in time. Sir Patrick Moore and his astronomical team give an intimate guide to one of the skies' most recognisable constellations.