Earth’s spin speeds up, making 22 July the second-shortest day ever

Earth’s Spin Speeds Up: Scientists Track Shortest Days Ahead (Representative Image: Canva)

Earth is doing something strange, and we’re just noticing. A spin so fast, you won’t feel it—but the clocks certainly will.

Earth is spinning quicker than usual, puzzling researchers worldwide. On July 22, the planet will complete its full rotation 1.34 milliseconds early. That’s shorter than the usual 24 hours, but still unnoticeable to people. Yet, the change matters. Atomic clocks are watching closely and may need adjusting. A “negative leap second” might be added by 2029—something that’s never happened before.

The planet’s spin hasn’t always been this way. Scientists say a day used to be just 19 hours long. Back then, tides from the sun and moon shaped Earth’s rotation. Over time, the moon has moved farther from Earth. As it drifted, it slowed our spin. That made days longer—until now.

Since 2020, records keep getting broken. The fastest day was July 5, 2024, when Earth spun 1.66 milliseconds quicker than normal. This year, July 10 claimed the top spot. July 22 is now the second-shortest day, followed by August 5, expected to be 1.25 milliseconds short.

Something Deep May Be Driving the Change
Experts aren’t sure what’s causing this speed-up. Some believe it’s linked to Earth's liquid core. If it’s slowing down, the mantle and crust may be spinning faster. Melting ice and rising seas may also play a small part by shifting mass around. But scientists say these aren’t enough to explain it fully.

Leonid Zotov from Moscow State University says the true cause is still unknown. He thinks the acceleration might soon stop, and Earth will return to longer days. If that happens, the planet’s quick spin may be just a brief phase.

Until then, Earth’s changing rhythm keeps ticking. And scientists will keep watching—down to the last millisecond.