Earth Spinning Faster, Days Getting Shorter: Scientists

In a subtle but scientifically significant development, scientists have confirmed that Earth is rotating slightly faster than usual, causing the length of our days to shorten by fractions of a millisecond.

While this change may go unnoticed in everyday life, it has critical implications for global timekeeping systems.

Trend Started in 2020, Could Prompt Leap Second Adjustment by 2029

When scientists talk about shorter days, they don’t mean by minutes or hours, but by mere milliseconds. These minute changes are measured with high-precision atomic clocks, which have tracked Earth's Length of Day (LOD) shortening steadily since 2020.

This acceleration, although slight, is enough to spark conversations among experts about the potential need for adjusting Coordinated Universal Time (UTC).

The trend of shorter days began in 2020 and has continued through 2025. According to experts, if this continues, 2029 could mark the first time in history that a leap second is subtracted rather than added to keep atomic time aligned with Earth’s rotation.

Earth’s Day Length Has Shifted Over Time

A day on Earth typically lasts 86,400 seconds, or 24 hours, based on its rotation. But this isn’t a fixed number. Over millions of years, Earth’s rotation has gradually slowed due to natural forces like gravitational interactions, internal core dynamics, and tidal forces from the Moon. During the age of dinosaurs, for instance, a day lasted about 23 hours. Looking ahead, scientists predict Earth may eventually see 25-hour days, though that change could take over 200 million years.

The Shortest Days on Record

The current record for the shortest day, measured via atomic clocks, was July 5, 2024, when the planet completed a full rotation 1.66 milliseconds faster than the standard 24 hours. Predictions for 2025 show similarly short days:

July 9: LOD of -1.30 ms

July 22: LOD of -1.38 ms

August 5: LOD of -1.51 ms

These are the shortest days of the year and reflect the continuing acceleration trend.

What Is a Leap Second and Why Might We Subtract One?

A leap second is a one-second adjustment occasionally added to atomic time to synchronize it with the Earth’s irregular rotation. Traditionally, leap seconds have always been added, not removed. However, if Earth keeps spinning faster, subtracting a leap second may become necessary for the first time ever to maintain that alignment.

Why Is Earth Spinning Faster?

The cause of this acceleration remains a scientific mystery. Researchers are considering various factors including seismic shifts, changes in the fluid core of the planet, and fluctuations in Earth’s angular momentum. The Moon, long known to slow Earth's spin through tidal friction, is still part of the equation, but other internal dynamics may be influencing the current acceleration.

Despite the rapid headlines, scientists stress there is no cause for alarm. While Earth’s rotation rarely speeds up, fluctuations like these have occurred in the past and usually stabilize over time. The long-term trend still suggests that Earth’s rotation is slowing down, not speeding up indefinitely.

According to the source: Republic World.