Think Of A Number, BBC-1, 24th October 1984

From the Radio Times billing: "A lighthearted exploration of science and numbers. This week, Johnny joins a galaxy of stars and discovers there's more to telescopes than meets the eye. Also find out how to make a map to help your star-spotting. From the sun to the stars, comets to constellations - it's all telescoped into an All Star Think of a Number Show".