Beginning July 9th, there will be three shortened days over the next few months. The day will be shortened by as much as a millisecond because of how the moon’s position relative to Earth is influencing the planet’s rotation.

Which 2025 Days Will Be Shortened and Why?

A standard Earth full rotation takes 24 hours, or exactly 86,400 seconds. According to the website TimeAndDate, the amount of time detracted from a day shortened by a number of milliseconds is called “length of day.”

According to USA Today, prior to 2020, the shortest “length of day” ever recorded by atomic clocks was -1.05 ms, which means the Earth completed one daily rotation in 1.05 milliseconds less than 86,400 seconds.

“Since then, however, Earth has managed to shatter this old record every year by around half a millisecond,” astrophysicist Graham Jones wrote for TimeAndDate.

Earth’s rotation is impacted by various factors, including the positions of the sun and moon, changes to Earth’s magnetic field, and the balance of mass on the planet. Recent research by NASA has suggested that dwindling ice and groundwater and rising seas have increased the “length of day” since 2000 by 1.33 milliseconds per century.

Scientists have predicted that Earth’s rotation will speed up enough to create three shortened days between July and August 2025, beginning on July 9th with a predicted -1.30 ms “length of day.” The next two shortened days are predicted for July 22nd (-1.38 ms) and August 5th (-1.51 ms).

According to LiveScience, the moon will be at its furthest point from the Earth’s equator on these days. This will alter the gravitational pull and make the planet spin faster on its axis.

Though it’s unlikely that we’ll notice such a small difference in our normal 24-hour day, atomic clocks may be thrown off. If they are, it may throw off servers, computers, GPS signals, and other networks that rely on accurate time, according to The Guardian.