On June 29, 2022, Earth made its fastest ever rotation – 1.59 milliseconds less than the usual rotation speed of 24 hours – marking the shortest day since the 1960s when records began, according to the International Earth Rotation and Reference Service Systems (IERS).

It's not the first time that our planet has spun faster. July 19 2020 was recorded as the shortest day of that year, when the Earth's rotation took 1.4602 milliseconds less than 24 hours. The following year in 2021, Earth rotated at generally increased speeds and did not break any records.

However this year, Earth has racked up unusual speeds. Continuing from its June quick spins, the planet on July 26, 2022, recorded the second-fastest spin of this year with a day that lasted 1.50 milliseconds less.

Why is Earth speeding up?

There are many suggestions but no conclusive proof as to why Earth is spinning faster. Some of the hypotheses include:

1. Loss of the weight at poles due to melting of glaciers

2. Ocean tides caused by seismic activities 

3. Moon's gravitational pull

4. The 'Chandler wobble' effect – as Earth is not perfectly spherical, which results in small deviation in its axis of rotation

"We don't know the cause of the acceleration of Earth's rotation. We have only hypothesis concerning the cause," said Christian Bizouard, from the Paris Observatory at International Astronomical Union.

"We assume that the cause is internal and lies in the movement of Earth's core. The crust which is linked to geological time scales, slides over the mantle and it is commonly assumed that the time variation is caused by this core-mantle interaction," he told CGTN.

"But we have only a speculative model of this theory based on the motion of the core," he added.

What are the consequences?

The change in Earth's rotation could have an effect on atomic clocks, which are used in GPS satellites, as they will need to be synchronized with the seconds lost, according to Bizouard.

There will also be potential consequences for communications systems within smartphones and computers, which synchronise with Network Time Protocol servers.

If the accelerating trend continues, a negative leap second will be required to balance the clocks, Bizouard said. But IERS said there is no need for such adjustment as of now. 

"There will not be a leap second introduced in UTC (Coordinated Universal Time) at the end of December 2022," it said in a statement.

Cover photo: Earth from space photographed by spacecraft Galileo 11. /Universal History Archive/Getty Images