Astronomers are used to fielding tough questions, but these are out of this world | Séamas O'Reilly

I suggest to my son that the object of going to the planetarium should be for him to learn something, not to catch the scientists out Since it was half-term, I took the boy out for the day. My choice was the planetarium at the Royal Greenwich Observatory, which melds my two great loves: space and having to traverse the entirety of London, with a chatty six-year-old, twice in one wet afternoon. Our journey involves two buses, a tube, an overground, and 20 minutes of walking either side. Time was,...