Year 2021

The Earth is moving faster than it ever has in the last 50 years, scientists have discovered, and could result in a ‘negative leap second’ being added to the year.

The speed of the Earth’s rotation is affected by a number of factors, including the motion of its molten core, oceans, and atmosphere.

As such the average day in 2021 is expected to be 0.05ms (milliseconds) shorter than the 86,400 seconds that usually make up a 24-hour period, according to Graham Jones, Astrophysicist & Science Communicator, and Konstantin Bikos from Time and Date.

Scientists at the International Earth Rotation and Reference Systems Service (IERS) can calculate when this event occurs by measuring the precise moment a star passes a certain location in the sky each day.

“In fact, the year 2021 is predicted to be the shortest in decades. The last time that an average day was less than 86,400 seconds across a full year was in 1937”, Jones and Bikos write.

Should the Earth’s rotation get out of sync with atomic clocks, a leap second can be added or subtracted to ensure they remain aligned.

These were first introduced in 1972, and since then only 27 leap seconds have been added to the year.