We’re up at Griffith Observatory, up on Mount Hollywood, fresh from the big room downstairs in which a facsimile of the solar system is displayed, and in which I, who may look 92, but am still four and a half at heart, got the giggles at the prospect of asking the Sherpa, or docent, or whatever, such questions as, “How big is Uranus?" and “What is Uranus’s average temperature?” We are in a long queue waiting to be admitted to a sort of domed theatre in which we will see a presentation called something like