Outrunning the Sun

If you visit Christ Church College at Oxford University, you might notice something rather strange among the fabled ‘dreaming spires’: the clocks are wrong. Or, rather, the clocks are right.

It’s not a huge difference. The clocks are just five minutes and two seconds behind Greenwich Mean Time – time as measured at the Royal Observatory in Greenwich, London, which forms the basis of the Coordinated Universal Time (UTC) used around the world. That five-minute gap exists because Oxford lies west of the Prime Meridian, the line of 0° longitude that runs through Greenwich. The further from London you go, the further ahead or behind UTC the local solar