Earth is spinning faster than usual: What experts say after shortest day ever

Time is flying. 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 both of these 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 began using atomic clocks to measure time, Forbes reported. July 26 neared the newly set record, at 1.50 milliseconds shorter than usual, according to timeanddate.com.

The shortened days are caused by the Earth spinning faster than usual, Interesting Engineering reported.

NASA via AP

This May 18, 1969, photo made available by NASA shows Earth from 36,000 nautical miles away as photographed from the Apollo 10 spacecraft during its trans-lunar journey toward the moon.

But why is the Earth spinning faster? Scientists are not completely certain, but they have a few competing explanations:

— Changes to the climate or climate systems, such as melting and freezing of glaciers or winds, whose shifting weight pulls on the Earth.

— Earthquakes and other seismic activity that move mass toward the center of the Earth, like a spinning person pulling arms in.

— Movement within the Earth’s molten core that shifts mass on the planet.

— Ocean circulation and pressure on the seabed that pulls on the Earth’s axis.

The “Chandler Wobble,” a natural shifting of the Earth’s axis due to the planet not being perfectly spherical, could be linked to the spinning speeds, timeanddate.com reported.

Australian astronomer Fred Watson explained to ABC: “When you start looking at the real nitty gritty, you realize that Earth is not just a solid ball that is spinning.”

“It’s got liquid on the inside, it’s got liquid on the outside, and it’s got an atmosphere, and all of these things slosh around a bit,” Watson said.

That sloshing around can influence the speed of the Earth’s spin.

Some scientists think this could be the beginning of a new period of shorter days.

Still, the possible implications of shorter-than-usual days — namely, a “negative leap second” where there is a coordinated effort to drop a second to catch up with solar time — are still quite a way off, ABC reported.