The planet’s rotation fluctuates as it travels around the sun, and measurements suggest we’re losing more than a millisecond during the long days of summer.

When the moon is positioned farther from Earth's equator and closer to the poles, its pull on the planet becomes weaker. With less resistance, Earth is able to spin a bit faster, which makes the day slightly shorter than usual.

Atomic clocks — among the most precise instruments humans have ever built — have been keeping track of Earth’s spin since the 1950s. But what they show today is unexpected. Our planet, which for decades had been slowing down in its rotation, is suddenly speeding up.