The planets and moons of our solar system are covered in volcanoes, some billions of years old and seven times the height of Mount Everest. Sir Patrick Moore discovers the havoc that volcanoes can wreak on our own planet, as well as elsewhere in our solar system.

Sir Patrick Moore celebrates the 700th episode of The Sky at Night at his home in Sussex, with the help of special guests Professor Brian Cox, impressionist and amateur astronomer Jon Culshaw and Lord Martin Rees, the Astronomer Royal. A stellar panel of astronomers gathers to answer vexing questions from the viewers, while Sir Patrick has a close encounter with his younger self.