Precise astronomical observations, combined with atomic clocks, have revealed that the length of a day is suddenly getting longer. Scientists don’t know why.
This has critical impacts not just on our timekeeping, but also on things like GPS and other precision technologies that govern our modern life.
Earth’s rotation around its axis has been speeding up over the past few decades. Since this determines how long a day is, this trend has been making our days shorter. In fact, in June 2022 we set a record for the shortest day over the past half a century or so.
However, despite this record, since 2020 that steady speedup has curiously switched to a slowdown. Now, days are getting longer again, and the reason so far remains a mystery.
While the clocks in our phones indicate there are exactly 24 hours in a day, the actual time it takes for Earth to complete a single rotation can vary ever so slightly. These changes sometimes occur over periods of millions of years, and other times almost instantly. For example, even earthquakes and storm events can play a role.
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