The Earth completes one rotation every 24 hours due to its axial rotation. But in recent weeks, scientists have recorded that the Earth is completing its rotation in a few milliseconds less time. That is, the length of the day is slightly decreasing. On July 22, 2025, the Earth completed a day in 1.46 milliseconds less time, which was declared **the second shortest day in history.
Various possible reasons for the change in the speed of the Earth
1. Global warming and melting of glaciers:
The melting of the ice at the North and South Poles is shifting the weight of the Earth closer to the center, which can speed up the rotation.
2. Earthquakes and geological movements:
Large earthquakes can cause slight changes in the rotation by affecting the internal structure of the Earth.
3. The effect of the Moon on gravity:
The attraction of the Moon and the Sun has a small effect on the axial speed of the Earth.
Does this matter to us?
A loss of a few milliseconds may seem imperceptible to ordinary humans, but in the world of technology this difference can be very important:
GPS satellite navigation operates on a very precise time system.
In financial markets, a difference of milliseconds can affect billions of dollars in transactions.
GPS clocks, which determine global time scales, may have to be readjusted.

Could “leap seconds” make a comeback?
In the 2000s, “leap seconds” were also added to time due to the Earth’s slowing speed. Now, if the Earth’s speed increases, “negative leap seconds” — i.e., slowing down time — could potentially be introduced for the first time.

What is a “leap second”?

A leap second is an extra second that is added to the international standard of time when the time of day and atomic clocks begins to differ due to a slight change in the rotation of the Earth. When the Earth slows down its rotation, the duration of the day becomes slightly longer than 24 hours. And the duration decreases as the rotation accelerates.
Such a difference is of a few milliseconds, but in the time system every second is valuable, especially in GPS navigation, satellites, Internet servers, international financial markets, Therefore, when the time of the Earth and the time of the atomic clock begin to diverge from each other, scientists add an extra second (leap second) so that the two systems become equal.

When is a leap second added?
Usually every few years, when the difference between Earth and clock time is 1 second. This second is added at the end of June or December, for example: 23:59:59 → 23:59:60 → 00:00:00
  Have leap seconds ever been removed?
So far, only extra leap seconds have been added, that is, when the Earth’s speed slows down. But in recent times, as you have seen, the Earth *is* spinning faster — so experts are considering whether in the future we may have to add a “negative leap second,” that is, one second less.
Predicting the future
Scientists also consider this change to be temporary. Some experts say that the Earth naturally changes its speed from time to time, which is part of the balance. A difference of a few milliseconds may seem insignificant to us, but in topics such as time and speed, it can be a world-shaking change. This increasing “speed” of the Earth has not only motivated scientists, but also raised questions about the concept of time.