Paris (AFP) – Question: When is a minute not a minute?
The answer: At 2359 Greenwich Mean Time (GMT) on June 30, when the world will experience a minute that will last 61 seconds.
The reason for the weird event is something called the leap second.
That’s when timekeepers adjust high-precision clocks so that they are in sync with Earth’s rotation, which is affected by the gravitational tug of the Sun and the Moo
Read more: http://www.businessinsider.com/afp-second-thoughts-is-a-tiny-addition-in-time-too-much-2015-6#ixzz3eUqnV4Iz