No leap seconds will be inserted at the end of December 2026, marking 10 years since the last leap second.
The International Earth Rotation and Reference System Programme (IERS), an international organization involved in determining Universal Time, has decided not to insert a leap second at the end of December 2026, a measure usually considered at the end of June and December each year to correct the discrepancy between astronomical and atomic time.
datacenter.iers.org/data/latestVersion/bulletinC.txt
There is a very slight difference between astronomical time, which is based on the Earth's rotation, and atomic time, which is based on atomic clocks. A 'leap second' is inserted to correct this difference by adding one second on a specific day. When a leap second is inserted, it is scheduled for the end of June or the end of December UTC, which in Japan time corresponds to 8:59:60 the following day. For details of the event held at the Akashi Municipal Astronomical Science Museum at the end of June 2015 (8:59:60 July 1st Japan time), please refer to the following article.
A report from the Akashi Municipal Astronomical Science Museum witnessing the very moment the leap second '8:59:60' was inserted - GIGAZINE
However, due to the discontinuity in time caused by the irregular addition of a second, and the potential for problems in systems requiring precise timekeeping, there have been calls to abolish leap seconds. As a result, the General Conference on Weights and Measures in 2022 decided to abolish leap seconds by 2035.
The last time a leap second was inserted was at the end of December 2016 (which corresponds to 8:59:60 AM on January 1, 2017, Japan time). Therefore, this decision means that there will be no leap seconds for a full 10 years.
Incidentally, the Earth's rotation speed is changing, and in recent years it has actually been accelerating. Calculations suggest that there is a high possibility that a 'negative leap second' will be necessary by 2029.
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in Note, Posted by logc_nt