From Paul Bowden, Nottingham, UK
Leah Crane writes a fascinating article about the TRAPPIST-1 star system, with its seven roughly Earth-sized planets. Just out of curiosity, I worked out how long it would take us to get there, as measured on board a ship. If a 1 g ship accelerates for the first half of the journey, and decelerates for the second half, it would take roughly 7.5 years for the astronauts, because of relativistic time dilation, but just over 40 years as measured on Earth (23 May, p 36). All we need is that spaceship!
