Today could be the shortest day in Earth’s history – here’s why it will be under 24 hours

Today is set to be one of shortest days in the Earth’s recorded history – meaning that it will be just under 24 hours.

According to data from the International Earth Rotation and Reference Systems Service (IERS), the change will result in the day being between 1.3 and 1.6 milliseconds shorter than usual.

The IERS, who first noticed the Earth speeding up back in 2020, is also predicting shorter days coming up on July 22nd and August 5th. The link between these dates is that they are when the moon is furthest away from the equator.

As for why the Earth has begun speeding up in recent years, the science is so far inconclusive. But the length of days has fluctuated over the course of Earth’s history and is even expected to reach the point of 25 hour days in several hundred million years’ time.

It’s not worth reaching to adjust your clock at the moment though as today’s change is so small that it can only be detected by the most accurate atomic clocks.

The IERS keep an eye on this to see when a time may need adjusting to the globally recognised Coordinated Universal Time (UTC).

This last happened in 2016, when one “leap second” was added at the end of December.

A bulletin confirmed this week that one more second will not be added at the end of 2025. However, a first ever negative leap second – taking one second away – could be applied in 2029.

Featured image via Canva