Earth Is Spinning So Fast That an Hour Could Eventually Disappear from World Time
Jakarta, CNBC Indonesia — For years, scientists added extra seconds to world clocks to keep them aligned with Earth’s slowing rotation. But the planet is now spinning faster, so that adjustment system is no longer considered workable. A new concept, the leap hour, has emerged; one day, it could mean that an entire hour is removed from world time, according to a report cited on Friday (16 October 2026).
Earth’s rotation has not proved a reliable basis for measuring time. Its rate gradually slowed throughout history, before beginning to accelerate around 2020.
Scientists have long been aware of this. As a result, people rely on atomic clocks as a more accurate reference. In 1967, the General Conference on Weights and Measures defined the second using the energy emissions of caesium-133 atoms. More precisely, one second is equivalent to 9,192,631,770 oscillations of a caesium-133 atom.
Scientists have had to reconcile atomic time with Earth’s rotation to prevent a substantial mismatch between human timekeeping and conditions on the planet. People would not want the seasons to shift by more than a month, for instance.
The system adopted was to add leap seconds to atomic clocks. Since 1972, a total of 27 seconds have been added.
“Essentially, we stop the clock for a few seconds so that Earth can catch up,” Konstantin Bikos and Anne Buckle wrote for Time and Date.
But Earth has not continued to slow down. Since around 2020, its rotation has instead accelerated, creating a new problem. Whereas time previously had to be added, at some point it may have to be reduced—a step that has never been taken and which is feared could disrupt computer systems, networks and satellites worldwide.
Even adding a leap second has caused major failures. On 30 June 2012, Reddit went down because its system was not prepared to handle the extra second.
Companies such as Google and Meta have had to work around the issue by spreading the adjustment over a longer period, but the approach is not used uniformly around the world. Concern has grown as Earth’s rotation has accelerated, given the possibility of a negative leap second that has never been tested. Scientists have described the risk as comparable to fears over the year 2000 computer bug.
The solution agreed upon is to increase the permitted difference between atomic clocks and Earth’s rotation from less than 0.9 seconds to a full hour. This means adjustments would no longer be made every few years; instead, one would be required only once the difference reached 3,600 seconds.
“If that leap hour happens, it will not happen for a very, very long time,” said Christian Bizouard, director of the Earth Orientation Centre in France. “This decision pushes the issue hundreds or even thousands of years into the future.”
The introduction of the leap hour could affect people’s lives in several ways:
Computer systems could be safer, as they would not need to be adjusted whenever an extra second is added.
The gap would become increasingly noticeable, and future generations might observe a difference between wall-clock time and the Sun’s movement.
Scientists would need to adjust their measurements; astronomers and Earth researchers would have to account for the widening gap.
An hour could eventually disappear: if the difference reached the limit, the adjustment would be made all at once, meaning an hour would be “lost” from the world calendar.