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Leap Second to Be Replaced by Leap Hour
· Confirmed
In Short: The leap second, used to align atomic clocks with Earth's rotation, will be replaced by a leap hour system to avoid potential negative leap seconds and infrastructure risks.
The leap second, introduced in 1972 to align atomic clocks with Earth's rotation, is set to be replaced by a leap hour system, according to experts at the National Physical Laboratory.
Setnam Shemar, Principal Scientist at the National Physical Laboratory, explained to IFLScience that the Earth's rotation has accelerated in recent years, increasing the probability of a negative leap second, which would require clocks to skip a second.
Shemar added that from May 20, 2027, a difference of up to one hour will be allowed before intervention is needed, ensuring the continuity of Coordinated Universal Time (UTC) for several centuries.
The leap second has been used 27 times since its introduction in 1972 to keep the 24-hour day aligned with Earth's rotation.
As the world has become more interconnected, the reliable implementation of leap seconds has become a concern, posing risks to national infrastructure.
Experts are reconsidering the leap second system due to the increasing probability of a negative leap second and the risks it poses.
The new resolution allows for time to depart from 0.9 seconds up to 3600 seconds (one hour), according to Universe Today.
The decision will not sever the link between UTC and UT1, which is important for applications such as astronomy and celestial navigation.
David Herald of the International Occultation Timing Association told Universe Today that the change does not affect the underlying issue of Earth's rotation being non-constant.
Herald explained that with the new arrangement, time will be strictly uniform, allowing for reliable prediction of astronomical events years in advance.
For events where location on Earth's surface is important, such as solar eclipses, nothing will change.
The decision to end leap seconds is likely to pass based on a majority vote of national delegates from many countries, who have been keen to end leap seconds for several years.
What this adds
The leap second's discontinuation aims to mitigate risks to national infrastructure and ensure the continuity of UTC for centuries.
What's confirmed
- The leap second, introduced in 1972 to align atomic clocks with Earth's rotation, is set to be replaced by a leap hour system, according to experts at the National Physical Laboratory.
- Setnam Shemar, Principal Scientist at the National Physical Laboratory, explained to IFLScience that the Earth's rotation has accelerated in recent years, increasing the probability of a negative leap second, which would require clocks to skip a second.
- Shemar added that from May 20, 2027, a difference of up to one hour will be allowed before intervention is needed, ensuring the continuity of Coordinated Universal Time (UTC) for several centuries.
- The leap second has been used 27 times since its introduction in 1972 to keep the 24-hour day aligned with Earth's rotation.
- As the world has become more interconnected, the reliable implementation of leap seconds has become a concern, posing risks to national infrastructure.
- Experts are reconsidering the leap second system due to the increasing probability of a negative leap second and the risks it poses.
- The new resolution allows for time to depart from 0.9 seconds up to 3600 seconds (one hour), according to Universe Today.
- The decision will not sever the link between UTC and UT1, which is important for applications such as astronomy and celestial navigation.
- David Herald of the International Occultation Timing Association told Universe Today that the change does not affect the underlying issue of Earth's rotation being non-constant.
- Herald explained that with the new arrangement, time will be strictly uniform, allowing for reliable prediction of astronomical events years in advance.
- For events where location on Earth's surface is important, such as solar eclipses, nothing will change.
- The decision to end leap seconds is likely to pass based on a majority vote of national delegates from many countries, who have been keen to end leap seconds for several years.
What's still developing
- The leap second could be scrapped as soon as October.
- But authorities are considering an immediate end to avoid the real possibility that the next leap second will be negative — meaning that clocks must skip, rather than gain, a second.
- Louis Climate change has slowed Earth’s rotation — and could affect how we keep time The leap second’s time is up: world votes to stop pausing clocks Rampant groundwater pumping has changed the tilt of Earth’s axis Earth’s magnetic field is acting up and geologists don’t know why An essential round-up of science news, opinion and analysis, delivered to your inbox every weekday.
- We are also slowing down (mainly due to tidal friction versus the Moon) to the tune of 2.3 milliseconds per day per century, requiring the insertion of an additional second on average every 500 days or so, to stay in step with observed time.
- The system also allowed for the subtraction of seconds, which was never instituted in practice.
- Another time-related dilemma was also addressed this month, when a key conference did away with the leap second and the alignment of Universal Time (UT1) with Universal Coordinated Time (UTC).
- What happens, for instance, to the flurry of emails sent worldwide during said anomalous second?
- This resolution will do away with the occasional insertion of the leap second by the International Bureau of Weights and Measures (BIPM).
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- This is a quirky little event that involves June 30 or December 31 ending up with the peculiar time of 23:59:60.
- Louis World’s timekeepers upend how they adjust time to avoid catastrophic ‘negative second’ The leap second’s time is up: world votes to stop pausing clocks Daily briefing: We’re close to reaching a 30% land-conservation target Melting ice solves leap-second problem — for now An essential round-up of science news, opinion and analysis, delivered to your inbox every weekday.
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