The Leap Second Is No More

After decades of debate, the leap second has been officially discontinued, according to a recent announcement. This decision eliminates a metric that most people are unaware of but has significant implications for everyday technology. The International Bureau of Weights and Measurements (BIPM) stated that they would stop issuing leap seconds in May 2027, after 32 have been added since 1972.

Leap seconds were introduced in 1972 to address a growing gap between atomic time and Earth's rotation, which is slowing down due to factors like tidal friction, the Earth's molten core, and oceanic influences. The leap second is added as needed by comparing atomic clocks with astronomical time, essentially adding a small extra track to keep the two times aligned.

While adding leap seconds has been challenging and caused issues for various systems, the risk of a negative leap second, which could have been dangerous, was deemed more severe. The BIPM chose May 20, 2027, as the date to discontinue the leap second, marking the anniversary of the Metre Convention signing. Although atomic time and astronomical time will continue to drift apart, the leap hour is scheduled for a future millennia to address this discrepancy.

In the meantime, systems relying on UTC will have no issues, while those using UT1 will need to account for the growing difference between the two.