Sir Patrick Moore on the success of The Sky At Night
The BBC's The Sky At Night programme was first broadcast on 24 April 1957 - making Sir Patrick Moore the longest-running presenter of the same television show in the world.
On Sunday, 6 March 2011 the programme celebrates its 700th episode, and Sir Patrick has fronted all but one of them.
The Today Programme's Sarah Montague went to his home, in Selsey on the south coast of England, to find out what he thinks the secret of the programme's success has been.
Moon images supplied by Nasa National Space Science Data Centre.
Watch highlight clips from more than 50 years of The Sky At Night