Days getting shorter, Earth spinning faster these days

6 August 2022

Scientists are perplexed by a slight increase in the speed of the Earth’s rotation in recent years. It’s all the more puzzling because as time has passed, Earth’s spin has been ever so gradually slowing down. This has required leap seconds to be added to clocks from time to time, which are separate to the leap day that needs to be added to the calendar every four years.

Since the first leap second was added in 1972, scientists have added leap seconds every few years. They’re added irregularly because Earth’s rotation is erratic, with intermittent periods of speeding up and slowing down that interrupt the planet’s millions-of-years-long gradual slowdown.

“The rotation rate of Earth is a complicated business. It has to do with exchange of angular momentum between Earth and the atmosphere and the effects of the ocean and the effect of the moon,” Levine says. “You’re not able to predict what’s going to happen very far in the future.”

But in the past decade or so, Earth’s rotational slowdown has … well, slowed down. There hasn’t been a leap second added since 2016, and our planet is currently spinning faster than it has in half a century. Scientists aren’t sure why.

While the speed increase is barely noticeable, the shortest day since the advent of atomic clocks was recorded on Wednesday 29 June 2022, when the day was 1.59 milliseconds shorter than the usual twenty-four hours.

A millisecond or so is small fry though. In the distant past, Earth’s years were made up of four-hundred-and-twenty days, considerably more that the three-hundred-and-sixty-five we’re accustomed to. But it could be worse. If say the Earth spun twice as fast as it presently does, life would be quite different.