Earth Is Spinning Faster This Summer: Atomic Clocks Might Need Adjusting Soon

Days seem longer in the summer and shorter in the winter due to the number of hours of sunlight, but is the Earth actually spinning faster than ever?

Scientists report that this summer’s rotation has Earth completing its days ever-so-slightly faster. July 10 was the shortest day of the year; 1.36 milliseconds shorter than 24 hours, with similarly brief days expected July 22 and August 5. While negligible for our daily rhythm, it poses headaches for precision timekeeping and could even lead to a rare “negative leap second” if it continues.

What happened to June 22?

Many people believe June 22 is the longest day of the year, but that’s only a recording of the number of hours of sunlight that officially begins summer. Conversely, the shortest day of sunlight is considered to be December 22. The opposite is true for countries in the southern hemisphere, much the same as the difference between seasons in the northern and southern hemispheres. Not only does it seem odd that shortened days would happen in the summer, but these are also supposed to be longer days. Of course, those hours of sunlight only take into account the Earth’s angle to the Sun, which creates the differences in seasons as well.

How could faster spinning become a problem?

The difference caused by the Earth spinning faster is negligible to most people. You would never notice a millisecond of time, but for timepieces and science that rely on extremely accurate measurements, this could be important. This trend of the Earth’s rotational behavior has been calculable in recent years and could lead to something strange. If it continues, the atomic clocks around the world will need to be adjusted by a full second in 2029, which has never been done before. This won’t change much, but if it continues, timepieces might have to be adjusted more often than ever before.

Keeping time

Timekeeping hasn’t always been part of human history. It took time for early humans to realize the rotational properties of the Earth in relation to the Sun and create a way to account for time. Although atomic clocks have never had to be adjusted in the past, they don’t date back to the earliest times of human existence. For all we know, seconds have been lost or gained in the past, but that change was never recorded because it was so small that it was extremely difficult for people to notice.

Isn’t Earth’s speed fixed?

The Earth isn’t a computer and hasn’t always had the same mass and physical makeup as it does now. We know that continents have moved over time, that tectonic plates shift, and the Earth is a living planet that changes all the time. However, we want to believe that we are in a fixed place and time in space, that’s not the case. Earth is spinning faster than before, but you don’t need to strap yourself to the ground to avoid being tossed off.

Scientists have found that the Earth used to spin much faster than it does today. A study performed in 2023 shows that a day on Earth used to be approximately 19 hours, not the 24 hours that we’re accustomed to now. This was discovered by studying the balance between solar atmospheric tides and lunar ocean tides. For most of the time humans have inhabited Earth, days have been longer than 19 hours. The main reason for this is the tidal friction from the moon, which has caused it to move gradually farther away from Earth. This causes Earth’s rotation to slow and days to be longer.

The atomic clock tells the story

The first atomic clock wasn’t invented until 1973, which means the phenomenon of longer and shorter days could have occurred many times in the past. Since that time, until 2020, the shortest day recorded was 1.05 milliseconds shorter than 24 hours, but since 2020, Earth continually breaks speed records, only set by itself, of course. The shortest day measured was July 5, 2024, which was 1.66 milliseconds faster than 24 hours.

This year, July 10 took the lead as the shortest day of the year at 1.36 milliseconds short of 24 hours, but other days will be close behind. July 22 will be 1.34 milliseconds short of the expected 24 hours, and August 5 is expected to be about 1.25 milliseconds shorter than usual. These figures and a “leap second” won’t impact most lives much at all, but it could disrupt the atomic clock.

Will this continue?

Can you feel the Earth spinning faster than usual? Not at all, but scientists who rely on precise timing and the atomic clock could find their work disrupted on some days. There are signs the acceleration might be easing because the rate of decrease in day length appears to be slowing. This is one of those unexpected and unexplainable phenomenon that makes life interesting. The only explanation that science could offer is that the moon is slightly closer to the Earth than it has been in more recent years.

Will the Earth spinning faster have any impact on your life? Only if we have the “leap second” in 2029, but if the spinning slows, that won’t occur, and you won’t have anything to worry about; not that you were truly worried in the first place.