In general, there are processes to indicate that they have lengthened the Earth’s day from its length of about 86,400 seconds. For millions of years, the planet’s rotation has been slowed down by the friction caused by the Moon. Every 100 years, about 2.3 milliseconds are added to the length of a day – billions of years ago, a day on Earth lasted only 19 hours. Now, however, Earth’s continued slowness is unprecedented and has continued for the past 50 years, and, overall, Earth’s rotation has slowed by about 6 hours over the past 2740 years, according to a study published in the Proceedings of the Royal Society A .in 2016. “The rotation rate is found to deviate from uniformity, so that the change in the length of the mean solar day (lod) increases at an average rate of +1.8 ms per century. This is significantly less than the rate predicted based on tidal friction, which is +2.3 ms per century,” the researchers wrote. Earth reached its shortest day on June 29, 2022, but the general trend is that the days are getting longer – with no immediate explanation. There are a few theories: weather systems that melt the ice sheets could have a long-term effect, as at lower altitudes the planet shrinks inward. However, these decrease at a steady rate, so they may not fit such a sudden change. It’s possible that fluctuations in the planet’s rotation speed, known as the “Chandler oscillation” – where a small, irregular movement of the Earth’s geographic poles across the planet’s surface – could cause an impact. Finally, processes in the inner or outer layers of the Earth, in the oceans, in the tides or even in the climate, may cause it. Large earthquakes can also change the length of a day, but the amount is usually minimal.
