Earth Spins Faster Than Ever
Earth’s Fastest Days
Scientists warn that some days this summer—July 9, July 22, and August 5—will be the shortest in history, up to 1.51 milliseconds shorter than usual. This happens because Earth’s rotation is speeding up. “Between 2020 and 2022, scientists noticed this phenomenon on atomic clocks,” devices that measure time precisely.
Why Earth Spins Faster
The exact cause isn’t clear, but factors like “changes in the atmosphere, the melting of glaciers, motion in the Earth’s core, and a weakening magnetic field” may be involved. Richard Holme explains, “mass is moved from the ground to above the ground — further away from the Earth’s spin axis,” making Earth spin faster, similar to a figure skater pulling in their arms.
Impact and History
Shorter days affect GPS, phone networks, and financial systems because they rely on exact timing. The Earth’s rotation varies by milliseconds over time, and “Earth started setting new records for the shortest day in 2020.” On July 5, 2024, Earth spun 1.66 milliseconds faster, the fastest day recorded.
Future Timekeeping
Normally, we add leap seconds to keep clocks aligned with Earth’s rotation, but if the speed keeps increasing, scientists “might have to eliminate a second, known as a negative leap second,” something never done before.
