Earth's rotation is slowing at a rate of 2.3 milliseconds a century, meaning days could eventually last 25 hours — but scientists say the change is so gradual it will go unnoticed in everyday life
Scientists have predicted that a day could last 25 hours in the future as the Earth is "slowing down". However, they believe the rate of slowdown is so small that it will be largely unnoticeable in day-to-day life.
Researchers attribute the change in speed to the ongoing gravitational tug-of-war between the Earth and the Moon. This force, which essentially acts as a brake on Earth's rotation, is also responsible for controlling the tides.
While we typically regard a day as 24 hours, NASA points out that Earth's orbit isn't a perfect circle, so some days run slightly longer than 24 hours, while others run slightly shorter.
READ MORE: Trump lie about Artemis II mission easily disproven with picture of BidenREAD MORE: NASA astronauts' deaths were so brutal special funeral had to be held for body partsAnother measure of a day's length is the time it takes Earth to complete a full rotation, known as a sidereal day. At present, this is estimated to take approximately 23 hours and 56 minutes.
The Moon, meanwhile, exerts a gravitational pull on Earth's oceans, generating the rise and fall of tides as the planet spins. However, these tidal bulges don't align perfectly with the Moon, according to Econews.
This misalignment occurs because friction between the ocean and the seafloor "steals" some of Earth's rotational energy. As a result, the Moon actually accelerates slightly due to this phenomenon.
Consequently, the Earth is drifting 3.8cm further from the Moon every year, while the length of a day is estimated to grow by approximately 2.3 milliseconds per century as the planet continues to decelerate. While this might appear "astonishingly small," the space agency explains it creates an "accumulated effect" on the planet. This means roughly 40 seconds could be lost over a century, leaving Earth an hour "behind schedule" by the millennium's end.
However, the Earth isn't decelerating at a consistent pace. Researchers point to the "non-tidal effects of climate change," including factors like global warming and polar ice cap changes, along with the Earth's molten core dynamics, making it "impossible" to forecast the transition.
The United States National Institute of Standards and Technology explains that "leap seconds" ensure Coordinated Universal Time (UTC) stays synchronized with the Earth's rotation period. This represents a calculation the institute describes as "standard" across all timekeeping methods.
At present, International Atomic Time, measured through 450 atomic clocks distributed across 80 laboratories worldwide, is 37 seconds ahead of UTC. The most recent "leap second" was introduced in December 2016.
Scientists now project that a 25-hour day could emerge in 200 million years, assuming the Earth and Moon maintain their current behavior. The Moon isn't the sole factor affecting the Earth's rotational speed either.
Research funded by NASA discovered that the redistribution of substantial masses like ice and water can also decelerate the planet. The study noted: "These resulting shifts in mass cause the planet to wobble as it spins and its axis to shift location - a phenomenon called polar motion.
"They also cause Earth's rotation to slow, measured by the lengthening of the day. Both have been recorded since 1900."
The pace at which the Earth has been decelerating has also accelerated since 2000, representing what experts describe as "a faster pace than at any point in the prior century". NASA's Surendra Adhikari stated: "In barely 100 years, human beings have altered the climate system to such a degree that we're seeing the impact on the very way the planet spins."