The leap second’s fate will be determined in January

Nature : At its meeting next January in Geneva, the International Telecommunication Union will decide whether to abandon the leap second. Thus the world’s official definition of the time of day would be decoupled from Earth’s rotation. First introduced in 1972, the leap second accounts for Earth’s slowing rotation rate and ensures that the Sun reaches its zenith over the prime meridian on average at exactly 12:00:00. Unfortunately for time keepers, Earth is spinning down at an erratic, unpredictable rate. Whereas seven leap seconds were added in the 1990s, only two were added in the 2000s. The unpredictability of leap seconds frustrates systems such as navigation satellites that require accurate timing. Indeed, the US GPS doesn’t use leap seconds at all. As Zeeya Merali reports for Nature, whether keeping track of leap seconds is a mild inconvenience or a serious problem is a matter of debate. Regardless of how January’s vote goes, Earth will continue to spin down. In her story, Merali quotes Peter Whibberley, a physicist at the UK’s National Physical Laboratory: “A century down the line, we’ll need to introduce a ‘leap minute,’ and nobody has any sensible arguments for why that won’t be a worse issue.”