What did you do with the extra 1.59 milliseconds on Wednesday, June 29, 2022? As reported by TimeAndDate.com, on that date our planet set a new fastest record—as far as scientists can tell—for completing one rotation. Hang on! Earth takes exactly 24 hours to rotate once on its axis, right? Almost, yes, but not exactly. Until a few years ago it had been thought that Earth’s rotation was slowing down after several successive measurements by atomic clocks since 1973.
The International Earth Rotation and Reference Systems Service (IERS) had even begun adding leap seconds every now and again to make up for the slower spin (it last happened on December 31, 2016). Over a longer time period that may still be the case—Earth’s rotation may, in general, still be slowing down. After all, the Moon is gradually slowing down the Earth’s rotation. Its gravitational pull causes tides and makes the Earth’s orbital path around the Sun slightly elliptical. However, in the last few years the atomic clocks have shown that Earth rotation is now speeding up. In fact, we could be beginning a 50 year period of shorter days.
In 2020 scientists recorded the 28 shortest days since 1960. Last year that trend did not continue, with the shortest day in 2021 being longer than in the previous year. However, on June 29, 2022 our planet completed its quickest-ever spin, followed quickly by a day that lasted 1.50 milliseconds less on July 26, 2022. The previous record for the shortest rotation was July 19, 2020, when the Earth’s rotation took 1.4602 milliseconds less than 24 hours. The cause of the differing speed of Earth’s spin is unknown, but theories abound:Earth’s quickening rotation has consequences because atomic clocks—which are used in GPS satellites—don’t take into account the Earth’s changing rotation.
