Could we soon delete a second to keep time in sync with Earth?

Science · Published 8 October 2026 Swipe more like this →

In short: Earth's rotation is unpredictable, and scientists suggest we might eventually need an unprecedented adjustment: deleting a second. While we currently add time to stay in sync, the shifting speed of our planet's spin may soon force a radical change to how we measure the passing of time.

To maintain alignment between Coordinated Universal Time (UTC) and the Earth's rotation, timekeepers occasionally add a leap second to the calendar. To offset the Earth's decelerating rotation, the BIPM (International Bureau of Weights and Measures) created this system in 1972. Whenever UTC becomes one second faster than the Earth's actual rotation, an extra second is inserted to bridge the gap. This mechanism ensures that our global timekeeping remains perfectly in tune with the planet's natural movements. By adding this interval, we prevent a growing discrepancy between human-made clocks and celestial mechanics.

However, this synchronization method has faced long-standing challenges. Judah Levine, previously a physicist within the U.S. National Institute of Standards and Technology's Time and Frequency Division, remarked that this solution has 'always been a problem.' Difficulties in making regular corrections arise from Earth's erratic rotation—which lately featured 28 of its quickest days on record. This unpredictability makes it difficult for scientists to predict exactly when these adjustments will be necessary. Consequently, the constant need for manual corrections creates ongoing technical hurdles for global time standards.

Because of these complexities, international timekeeping authorities are considering a significant shift. As early as 2027, there is a proposal to move away from the single leap second in favor of a much larger adjustment: a leap hour. This would fundamentally change how we manage the relationship between atomic time and the physical rotation of our planet, addressing the inherent difficulty in matching a steady clock to a fluctuating world. This proposed change aims to simplify the process of maintaining temporal accuracy. Such a shift would provide a more stable way to manage the relationship between atomic and solar time.

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