Scientists predict a day will last 25 hours as 'Earth slows down'
Scientists have predicted that a day could last 25 hours as the Moon's gravitational pull gradually slows down Earth's rotation
Scientists have forecast that a day could stretch to 25 hours in the future as the Earth is "slowing down". However, they believe the rate of deceleration is so minimal that it will be barely noticeable in everyday life.
Researchers attribute the change in speed to the perpetual gravitational tug-of-war between the Earth and the Moon. This force, which essentially acts as a brake on the Earth, is the very same one responsible for controlling the tides. While we regard a day as lasting 24 hours, NASA clarifies that Earth's orbit isn't a perfect circle. Some days are fractionally longer than 24 hours while others are slightly shorter.
Another means of measuring the length of a day is by calculating how long it takes Earth to complete a full rotation, known as a sidereal day. It is currently estimated that Earth takes approximately 23 hours and 56 minutes to rotate fully.
The Moon, meanwhile, governs Earth's oceans through the force of gravity. It generates a rise and fall in the tides as the planet spins, though the tidal bulges do not align perfectly with the Moon, according to Econews.
This occurs because the ocean and the seafloor generate friction, which "steals" some of the rotational energy from the Earth. Simultaneously, the Moon accelerates slightly as a result of this phenomenon.
Consequently, the Earth is also drifting 3.8cm further from the Moon each year, while the length of a day is said to increase by approximately 2.3 milliseconds per century owing to this gradual slowdown. And while this may appear "astonishingly small," the space agency maintains it has an "accumulated effect" on the planet. This means Earth could lose roughly 40 seconds over the course of a century, finding itself an hour "behind schedule" by the end of the millennium.
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However, the Earth is not slowing at a consistent rate. Scientists point out that the "non-tidal effects of climate change," encompassing factors such as global warming, the polar ice caps, and the dynamics of the Earth's molten core, render it "impossible" to forecast the shift.
The United States National Institute of Standards and Technology states that "leap seconds" ensure Coordinated Universal Time (UTC) keeps pace with the time it takes the Earth to complete a full rotation — a calculation it describes as "standard" across all methods of timekeeping.
At present, International Atomic Time, measured using 450 atomic clocks housed across 80 laboratories, differs from UTC by 37 seconds. The most recent "leap second" was added back in December 2016.
Scientists now predict there could be a 25-hour day in 200 million years' time, should the Earth and Moon continue functioning as they currently do. The Moon is not the sole factor influencing the Earth's rotation, however.
A NASA-funded study discovered that the redistribution of large masses, such as ice and water, can also decelerate the planet. It stated: "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 rate at which the Earth has been decelerating has also accelerated since 2000, something described as "a faster pace than at any point in the prior century". Surendra Adhikari from NASA said: "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."
