- Our planet is rotating faster than it has in the last half-century, resulting in our days being slightly shorter
- If it keeps spinning faster, scientists say they may have to remove a second from clocks
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, according to Popular Mechanics, a science and technology magazine.
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. Meanwhile, 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, a media platform that covers science-related news and innovations reported.
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 which move mass toward the centre of the Earth, like a spinning person pulling their 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 as the planet is not perfectly spherical – could be linked to the spinning speeds.
According to Interesting Engineering, some scientists think this could be the beginning of a new period of shorter days.
Australian astronomer Fred Watson explained to the Australian Broadcasting Corporation (ABC), saying “when you start looking at the real nitty gritty, you realise 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.
According to ABC, that sloshing around can influence the speed of the Earth’s spin. 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 – is still quite a ways off.