During the past year, our planet exhibited an increase in the speed of its rotation on more than one occasion, potentially necessitating certain correctional measures by "international timekeepers" in the future, Live Science reports.
According to the media outlet, the "28 fastest days on record" since 1960, when Earth completed its rotation around its axis "milliseconds faster than average", all occurred in 2020, though the planet's rotation speed apparently varies all the time.
Previously, the minor discrepancies between astronomical time and Coordinated Universal Time (UTC), which emerge due to these fluctuations in Earth's rotation speed, were resolved by adding a so-called "leap second" to the year at the end of June or December, thus "bringing astronomical time and atomic time back in line".
However, while the addition of these leap seconds was performed as a result of the fact that "the overall trend of Earth's rotation" has been "slowing" since the implementation of accurate satellite measurement in the second half of the 20th century, an acceleration of our planet's spin may potentially require the use of a "negative leap second", the media outlet notes.
"It's quite possible that a negative leap second will be needed if the Earth's rotation rate increases further, but it's too early to say if this is likely to happen," physicist Peter Whibberley of the National Physics Laboratory in the UK said, as quoted by The Telegraph. "There are also international discussions taking place about the future of leap seconds, and it's also possible that the need for a negative leap second might push the decision towards ending leap seconds for good."
The media outlet points out, however, that the International Earth Rotation and Reference Systems Service in Paris, which is responsible for "determining whether adding or subtracting a leap second is necessary”, shows “no new leap seconds scheduled to be added".