In a latest study, scientists have revealed that the Earth has been taking ‘slightly less’ time to complete one rotation in recent times resulting in days being slightly shorter than average days. In 2020, for the first time in over 50 years, scientists had recorded 28 short days and expect days in 2021 to be even shorter.
According to the experts, average days have become around 0.5 seconds shorter than 24 hours. Scientists had started keeping records from the 1960s and observed July 19, 2020, as the shortest day, about 1.4602 milliseconds shorter than 24 hours. Scientists believe that in 2021, an average day will be 0.05 milliseconds shorter than 86,400 seconds, which is equal to 24 hours.
A total lag of about 19 milliseconds was recorded by the atomic clocks that keep ultra-precise records of a day’s length and have been doing so since the 1960s.
If Earth’s rotation gets out of sync against the ‘super-steady beat’ of the atomic clocks, the addition of a positive or a negative leap second can help align the time. The scientists, for this very reason, have proposed to add a ‘negative leap second’. Leap seconds which are similar to leap year, are adjustments of time. The National Institute of Standards and Technology (NIST) describes a leap second as a second that is added to Coordinated Universal Time (UTC) in order to keep it synchronized with astronomical time.
The ‘negative leap second’ has been debated if there is a need to subtract a second from the time to cover up the change and align the precise passing of time with Earth’s rotation, according to a report in Live Science.
The addition of a ‘negative-leap second’ is very new and has never been done before. However, there has been a total of 27 ‘leap seconds’ that has been added since the 1970s because it was taking longer than 24 hours for Earth to complete one rotation.
“It is certainly correct that the Earth is spinning faster now than at any time in the last 50 years…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”, Peter Whibberley, a senior research scientist with National Physical Laboratory’s time and frequency group, told The Telegraph. He also said that the need for a negative leap second might also lead to the decision of ending ‘leap seconds’ altogether.