Even by 2020, 2020 has not escaped intact.
The 28 fastest days on record (since 1960) all took place in 2020, with Earth the revolution to complete its as milliseconds faster than average. This is not particularly worrying – the rotation of the planet varies slightly all the time, driven by variations in atmospheric pressure, winds, ocean currents and the movement of the core. But it is inconvenient for international timekeepers, who use ultra-accurate atomic clocks to measure the Coordinated Universal Time (UTC) with which everyone sets their clocks. If astronomical time, set at the time it takes the Earth to make one full rotation, deviates more than 0.4 seconds from UTC, UTC gets an adjustment.
Until now, these adjustments have consisted of adding a “jump second” to the year end of June or December, which re-aligns astronomical time and atomic time. These frightening seconds were tackled because of the overall trend of Earth’s rotation has slowed down since accurate satellite measurements began in the late 1960s and early 1970s. Since 1972, scientists have added an average of one and a half leap seconds each year, according to the National Institute of Standards and Technology (NIST). The last addition was in 2016, when an extra “scare second” was added on New Year’s Eve at 23 hours, 59 minutes and 59 seconds.
Related: 5 of the most accurate watches ever made
But by Time and Date, the recent acceleration in Earth’s rotation scientists spoke for the first time about a negative leap second. Instead of adding a second, they may have to subtract one. This is because the average length of a day is 86,400 seconds, but an astronomical day in 2021 will be on average 0.05 milliseconds shorter. Over the course of the year, this will result in a delay of 19 milliseconds in atomic time.
“It is quite possible that a negative leap second will be needed if the rotation of the earth rises further, but it is too early to say whether this will probably happen,” said physicist Peter Whibberley of the National Physics Laboratory in the UK said. told The Telegraph. “There are also international discussions about the future of leap seconds, and it is also possible that the need for a negative leap second could drive the decision to end the leap seconds.”
The year 2020 was astronomically faster than usual (sigh of relief). According to Time and Date, the earth broke the previous record 28 times for the shortest astronomical day, set in 2005. That year’s shortest day, on July 5, the Earth completed 1,0516 milliseconds faster than 86,400 seconds. The shortest day in 2020 was July 19, when the planet completed one turn of 1.4602 milliseconds faster than 86.400 seconds.
According to the NIST, switching seconds have their pros and cons. It is handy to make sure that astronomical observations are synchronized with the clock time, but this can be a problem for some datalog applications and telecommunications infrastructure. Some scientists from the International Telecommunication Union have suggested that the gap between astronomical and atomic times be widened until a “scare hour” is needed, which will minimize the disruption of telecommunications. (In the meantime, astronomers will have to make their own adjustments.)
The International Earth Rotation and Reference Systems Service (IERS) in Paris, France, is responsible for determining whether a leap second should be added or subtracted. At the moment the Irish according to the service show no new leap seconds Earth Orientation Center.
Originally published on Live Science.