Time isn’t just flying this summer—it’s literally shrinking. Scientists say Summer 2025 will deliver three of the shortest days we’ve ever measured, thanks to an unexpected twist in Earth’s spin.
Normally, our home planet takes about 86,400 seconds—exactly 24 hours—to make a full rotation. But this July and August, three days will come up short by up to 1.51 milliseconds, according to new data reported by Popular Mechanics. That might sound tiny, but when you’re talking about a whole planet, it’s anything but trivial.
Mark your calendar: July 9, July 22, and August 5 are the record-breakers. They’ll join the ranks of July 5, 2024, which now holds the title for shortest day since modern tracking began, shaving off 1.66 milliseconds for reasons scientists still can’t fully explain.
So what’s speeding Earth up? For once, it’s not humans. Instead, experts like Leonid Zotov from Moscow State University say the usual suspects—ocean currents and wind patterns—can’t account for this sudden acceleration. It’s likely something deep inside our planet, but the exact cause is still a mystery. What we do know is that the Moon’s distance from the equator this season is giving Earth’s spin an extra nudge.
If this trend keeps up, official timekeepers might have to do something they’ve never done before: add a “negative leap second” by 2029 to keep our clocks in sync with reality. Geophysicist Duncan Agnew calls it a small but telling sign that we’re living in unusual times.
Fun fact: The 24-hour day hasn’t always existed—back in the Bronze Age, Earth spun so fast our days lasted only about 23 hours. It looks like history might be spinning back around.
