The length of Earth’s days has been mysteriously increasing, and scientists don’t know why

Atomic clock, combined with the right astronomy measurement, has revealed that the length of one day suddenly is getting longer, and scientists do not know why. This has a critical impact not only on our timeliness, but also things like doctors and other technologies that regulate our modern life.

Over the past few decades, the rotation of the earth around its axis – which determines how long one day – has accelerated. This trend makes our days shorter; In fact, in June 2022 we made a record for the shortest day for the last half century or more. But apart from this note, since 2020 Speedup which is stable strangely switched to a slowdown – the day is getting longer, and the reason so far is a mystery. While the clock on our cellphone shows that there are exactly 24 hours a day, the actual time needed by the earth to complete a single rotation is slightly different. These changes occur during millions of years to almost instant – even earthquakes and storm events can play a role.

It turns out that a day is very rare exactly the number of magic 86,400 seconds. Planet that has always changed for millions of years, the rotation of the earth has slowed down because of the friction effect associated with tides driven by the moon. The process adds about 2.3 milliseconds to long every day every century. A few billion years ago one day Earth was only about 19 hours.

Over the past 20,000 years, another process has worked in the opposite direction, accelerating the rotation of the earth. When the last ice age ends, the polar ice sheet that melts reduces surface pressure, and the earth’s coat begins to move steadily towards the pole.

Just like a ballet dancer rotates faster when they carry their arms towards their bodies – axis where they rotate – so that our planet’s rotation rate increases when the mass of this mantle moves closer to the earth’s axis. And this process shortens every day about 0.6 milliseconds every century.

More than a few decades and longer, the relationship between the interior and the surface of the earth also plays a role. Large earthquakes can change the length of the day, although usually with a small amount. For example, a great Tōhoku earthquake in 2011 in Japan, with a large amount of 8.9, is believed to have accelerated the rotation of the earth with a relatively small microdetic. Apart from these large scale changes, during shorter periods of weather and climate also have an important impact on the rotation of the earth, causing variations in both directions.

The tidal cycle two weeks and monthly moved the masses around the planet, causing changes in length to one millisecond in both directions. We can see the tidal variations in the length of the day for the period for 18.6 years. Our atmospheric movement has a very strong effect, and sea currents also play a role. Seasonal snow closure and rainfall, or groundwater extraction, change things further.

Why does the earth suddenly slow down? Since the 1960s, when the radio telescope operator around the planet began to compile techniques to simultaneously observe cosmic objects such as Quasar, we have a very appropriate estimate about the rotation rate of the earth. The ratio between this estimate and the atomic clock has revealed the length that seems increasingly underestimated the days over the past few years.

But there is a surprising disclosure as soon as we take fluctuations in the rotation speed that we know occurs because of the ups and downs and seasonal effects. Although the earth reached its shortest day on June 29, 2022, the long -term trajectory seems to have shifted from shortening to an extension since 2020. This change has never happened before for the last 50 years. The reason for this change is unclear. It could be due to changes in the weather system, with the back-to-back La Niña event, even though this has happened before. It could be an increase in the fusion of the ice layer, even though it does not deviate from a stable melting level in recent years. Could it be related to a large volcanic explosion in Tonga which injects WA in large quantities