Science & Tech · Science & Environment · 7 hrs ago
Leap seconds will end under new time rules from May 2027
A global standards conference agreed to end leap seconds from 20 May 2027.
Leap seconds have been added to Coordinated Universal Time (UTC) to keep it close to time measured by Earth's rotation, which varies slightly.
The change removes sudden one-second adjustments that can disrupt data centres, telecommunications, satellite navigation and power grids.
Germany's Physikalisch-Technische Bundesanstalt in Braunschweig says household radio clocks will not need changes, but observatories that use Earth's rotation to aim telescopes will need to account for a growing difference.
UTC and Earth's rotation may eventually differ by up to an hour, though experts expect that to take centuries.
The new rules take effect in May 2027, and the PTB is also researching nuclear clocks that could improve timekeeping in the future.
Those clocks will need several more years of research before they can be used for more precise time scales.
The General Conference on Weights and Measures has decided to end leap seconds, with the new rules taking effect on 20 May 2027.
Coordinated Universal Time will continue at a steady rate, while the difference between atomic time and Earth’s rotation may grow to as much as one hour.
Since 1972, 27 leap seconds have been added to keep the two time scales within 0.9 seconds of each other.
The change is intended to avoid technical problems caused by inserting or potentially removing a second.
The Physikalisch-Technische Bundesanstalt says radio-controlled clocks will not need changes, but some observatories may need to account for a larger difference.
- Who
- The General Conference on Weights and Measures (CGPM) decided to end leap seconds.
- What
- Leap seconds will be abolished, and UTC will run continuously. The difference between atomic time and Earth’s rotation may eventually reach one hour.
- When
- The new rules take effect on 20 May 2027.
- Where
- The decision was made in Versailles and applies to Coordinated Universal Time worldwide.
- Why
- Leap seconds can cause problems for technical systems. Faster Earth rotation also raised the possibility of a negative leap second.
This story does not have two clearly opposing sides.
Leap seconds began to be added to keep UTC and Earth-rotation time within 0.9 seconds of each other.
The most recent leap second was added.
WA.de reported that the CGPM had decided to abolish leap seconds.
The new rules for continuous UTC are due to take effect.
- Decision-maker
- General Conference on Weights and Measures (CGPM)
- Effective date
- 20 May 2027
- Leap seconds added since 1972
- 27
- Most recent leap second
- 2016
- Maximum future difference
- One hour between atomic time and Earth’s rotation
- Radio time signal
- DCF77, controlled by PTB
3 sources
What people are saying
If there are no more leap seconds, this part of the transmitted code simply remains inactive.
So for us, this involves no technical effort.