Is there an explanation?, What has been happening since 2020?, How fast does the Earth spin?, What is a leap second?

We’re told that the Earth takes 24 hours to rotate on its axis, and that one rotation equals one day. However, that hasn't always been true. During the Mesozoic age, days were only 23 hours long and around 200 million years from now, days will be 25 hours long. Although the Earth’s trend is to slow down, researchers have noticed that since 2020 the Earth’s rotation has actually been speeding up. So, what's going on? (Picture: Getty)

The Earth’s rotation speed could mean that in 2029, for the first time ever, we may need to take second away from the year. A report from Timeanddate.com revealed that, according to data from the Internal Earth Rotation and Reference Systems Service (IRES), the three shortest days (mathematically) this year will be July 9, July 22, and August 5 (Picture: Getty)

These are the dates when the Moon will be the furthest from the equator, which has an impact on the Earth’s rotation. It’s thought that the shortest day will be August 5, at around 1.51 milliseconds shorter than average. The record holder since this rotational trend began is July 5, 2024, which was 1.66 milliseconds shorter than average (Picture: Getty)

Is there an explanation?

Speaking to Timeanddate.com, Dr Leonid Zotov, a leading authority on Earth rotation at Moscow State University, said: ‘Nobody expected this. The cause of this acceleration is not explained. Most scientists believe it is something inside the Earth. Ocean and atmospheric models don’t explain this huge acceleration.’ But this won’t last forever, he predicts, adding 'sooner or later, Earth will decelerate’ (Picture: Getty)

What has been happening since 2020?

Since the trend was observed in 2020, the Earth rotating faster has become a little more usual. On July 9, 2021, the day was 1.47ms less than normal. The following year on June 30, it was reduced by 1.59 milliseconds. In 2023, on July 16, it was 1.31 milliseconds shorter. Although this may not sound so serious, a few milliseconds can make a difference for precise timekeeping and space navigation. It could even have an impact on computer systems (Picture: Getty)

How fast does the Earth spin?

At the equator, the Earth spins at around 1,000 miles per hour. The time it takes the Earth to complete one full rotation on its axis with respect to distant stars is actually 23 hours 56 minutes and 4.091 seconds - known as a sidereal day. But the speed of rotation isn’t consistent across the planet. As you move north or south, the circumference of Earth gets smaller, so the speed of spin reduces until it reaches its slowest at both poles (Picture: Getty)

What is a leap second?

Leap seconds are a way researchers synchronise our clocks with the Earth’s rotation to allow for more precise timing as it's needed for navigation and space purposes. This means leap seconds are usually added at the end of June or December. However, this year the IRES announced that ‘no leap second will be introduced at the end of June 2025’. This is because the Earth’s rotation has been fast lately, so it may be unlikely that any leap seconds will be added in the near future (Picture: Getty)