It is not yet perceptible to the eye, but the length of days on Earth is getting longer. According to astronomical clocks, very different from those of our mobile phones, the days are slowly getting longer. And even if in June 2022 the record for the shortest day of the last half century was set, the general trend is that of a slowdown in rotation and therefore lengthening of the days. The reason is still quite mysterious.
However, it must be considered that the length of the days is never exactly 24 hours, that is 86,400 seconds, since daily changes or of great impact, such as an earthquake, can vary the length of the day.
To confirm this trend are the two authors of the article published on The Conversationwho are respectively the director of the ARC Australian Center for Excellence in Antarctic Science, Matt King and the lecturer at the University of Tasmania’s School of Geography, Planning, and Space Sciences, namely Christopher Watson.
The days are getting longer: an evolving planet
“Will the sun rise tomorrow? Maybe“, He answered David Hume, one of the greatest exponents of the empiricist current of the eighteenth century. This sentence responds in a simple way to what is the idea of the philosopher and the man of science, or that the knowledge of the human being is constituted by experience and habit based on impressions and ideas. In fact, if until today we have thought that a day was composed of 24 hours, that is 86,400 seconds, it is good to know that it will not always be like this.
The rotation of the Earth over millions of years has slowed down due to the tides. Over the course of millions of years this process has lengthened the duration of each dayso much so that in some billions of years this time adds up to a total of 19 hours.
On the one hand the earth slowdown, on the other his acceleration. In fact, over the past 20,000 years, write Matt King and Christopher Watson, the Earth has been accelerating. After the last ice age, the melting of the ice caps reduced the surface pressure and the Earth’s mantle began to move steadily towards the poles. The example to explain this phenomenon is that of a dancer who turns faster when she brings her arms close to her body, that is the axis on which they rotate, thus also increasing the rotation of our planet. This process reduces the duration of each day by 0.6 milliseconds in a century.
The processes of slowdown And acceleration are therefore natural, but there are also force majeure events such as earthquakes that can instantly vary the acceleration or slowdown of the earth and can therefore also cause variations in the duration of the days.
The earth is slowing down: new mystery for science
The slowdown of the Earth is under discussion, but the most accredited hypotheses are those that trace the phenomenon back to rather recent events, for about fifty years, since they are visible thanks to technological innovations. In fact, it seems that it is the meteorological changes and therefore the climate change to vary the length of the days. It could in fact be the increase in the melting of the ice caps, or the huge explosion of the volcano in Tonga or who knows what other phenomenon.
Scientists then hypothesized that the change in the speed of the planet’s rotation is related to a phenomenon called “Chandler wobble,” which is a small deviation in the Earth’s axis of rotation.