Time flies. Literally.
Scientists at the National Physical Laboratory in England recorded the shortest day ever on June 29 and another shortened day on July 26, Popular Mechanics reported.
On those two days, the Earth completed its usual 24-hour rotation in less than 24 hours, The Guardian reported. June 29 was 1.59 milliseconds shorter than usual – the shortest day since the 1960s when scientists started using atomic clocks to measure time, Forbes reported. July 26 came close to the newly set record, 1.50 milliseconds slower than usual, according to timeanddate.com.
The shortened days are due to the Earth spinning faster than usual, Interesting Engineering reported.
But why does the Earth spin faster? Scientists aren’t completely certain, but they have a few competing explanations:
Changes in climate or weather systems, such as melting and freezing glaciers or winds, whose changing weight pulls on Earth, the New York Post reported.
Earthquakes and other seismic activity that moves mass toward the center of the Earth, like a spinning person pulling their arms out, The Guardian reported.
Movement in Earth’s molten core that moves mass across the planet, Forbes reported.
Ocean circulation and pressure on the seabed that pull on the Earth’s axis, ABC reported.
The “Chandler Wobble” – a natural shift in Earth’s axis due to the planet not being perfectly spherical – could be related to rotational speeds, timeanddate.com reported.
Australian astronomer Fred Watson explained to ABC, saying “when you start looking at the real detail, you realize the Earth isn’t just a solid spinning ball.”
“There’s liquid inside, there’s liquid outside, and there’s an atmosphere and all of those things kinda move,” Watson told ABC.
This sloshing can influence Earth’s rotational speed, ABC reported.
Some scientists believe this could be the start of a new period of shorter days, Interesting Engineering reported.
Still, the possible implications of shorter-than-usual days — namely a “negative leap second” where there’s a coordinated effort to give up a second to catch up with solar time — are still a long way off, ABC reported.
This story was originally published August 2, 2022 12:02 p.m.