It’s summer, but Aug. 5 will be the one of the shortest days of 2025. Here’s why
Tuesday, Aug. 5, will be one of the shortest days of the year — but it may not feel like it, according to Space.com.
A 24-hour day is normally 86,400 seconds. Aug. 5 is predicted to be 1.25 milliseconds short of a full day (a millisecond is equivalent to 0.001 seconds).
Though this loss of time will not be noticeable, it is an indication that the earth is rotating faster than normal.
And this isn’t the first time this year where days have been milliseconds shorter than the typical 24 hours. On July 9, the day was 1.23 milliseconds shorter, and on July 22, the day was 1.36 milliseconds shorter.
Scientists are not entirely sure why the earth is rotating faster than normal on these days, but here is some more information that gives context to what is happening.
Why is Earth rotating faster than normal?
The earth completes a full rotation around the sun in 24 hours. This is called a “solar day” and is measured from noon to noon.
The reason the earth is rotating faster on these three days in 2025 is unexplainable, leading authority on Earth rotation Leonid Zotov told Time and Date. However, scientists can infer that the shorter days are due to the Earth’s gravitational pull to our moon, and any long-term variations in Earth’s spin speed can be affected by factors like the complex motion of Earth’s core, oceans, and atmosphere.
“Our planet spins quicker when the moon’s position is far to the north or south of Earth’s equator,” according to Time and Date.
On Aug. 5, the moon will be at its maximum distance from the earth’s equator, making the rotation faster, and thus, the day 1.25 milliseconds shorter.
Has this happened before 2025?
Since 2020, there has been at least one shortened day a year. 2025 is the first year to have three shortened days within a 365-day period. Before then, the shortest length of day ever recorded was -1.05 milliseconds, according to Time and Date.