On October 15, in Versailles, France, the world's timekeepers voted to end the leap second. They will not wait until 2035, the year they chose in 2022. Starting on May 20, 2027, official time will run without those one-second jumps.
A leap second is an extra second added to the world's official clock. A normal minute has 60 seconds. When timekeepers insert a leap second, one minute becomes 61 seconds long. The point is to keep atomic clocks, which tick at a perfectly steady rate, lined up with Earth's spin, which does not. Earth can speed up or slow down by tiny amounts, so the two clocks slowly drift. Until now, when the gap grew too large, they added that spare second. That fix is now over.
They moved the date up because of a risk they do not want to take. In recent years Earth has sometimes been spinning faster. That could force the opposite move: a "negative leap second," which would drop a second instead of adding one. A 2025 workshop put the chance of needing one by 2035 at about 30 percent. No one has ever applied a negative leap second. The meeting decided not to wait and find out. "After 30 years of debates, we are ready," said Noel Dimarcq, who leads the time committee at the conference.
From that date, Coordinated Universal Time, the scale behind phones and computers, will be continuous. Atomic time and Earth's rotation may drift by as much as one hour. If a correction is ever needed, it would be a leap hour, not a leap second. Officials say that kind of fix should not be necessary for several centuries.
Most people will not feel a thing. Noon will still look like noon. The quiet change is for machines. They will no longer have to handle a sudden extra second, or a missing one. Official time will follow the smooth beat of atoms, and leave the Sun a little further behind.