Strictly speaking, a day lasts 86,400 seconds. On June 30, the day will officially be a bit longer than usual because an extra second or “leap” second will be added and Nasa has an explanation for this. “The Earth’s rotation is gradually slowing down a bit, so leap seconds are a way to account for that,” said Daniel MacMillan, Nasa’s Goddard Space Flight Center in Greenbelt, Maryland. This is the […]