Our planet is a dynamic object subject to many changes. For example, as early as 2020, a team of researchers warned that the The Earth’s magnetic field was weakening. These changes are not only limited to magnetism, which in addition to weakening, periodically changes polarity every 400,000 years or so, but they can also affect the orbit of the planet as described by the so-called Milankovitch cycles. And it is that according to the theory of this Serbian scientist named Milutin, the variations of the earth’s orbit would be responsible for the succession between the glacial and interglacial periods in which the geological history of our planet is divided.
Faced with this great variability, and because of a qualitative increase in the ability of human beings to measure the constants that govern our world, a new question has arisen in recent years: is the speed of rotation of the Earth uniform ? Scientists have long known the answer: the speed of rotation of our planet can vary, and it has done so for the 4,500 million years it has orbited the Sun. In fact, we know that there was a time on our planet, about 1,400 million years ago, when a day on Earth lasted only about 19 hours.
However, thanks to the high accuracy of atomic clocks, researchers have come across puzzling facts in recent years. So, just a few weeks ago, on July 19, 2022, scientists recorded what was the shortest day on Earth since measures began to be taken in this regard in the 1960s.
Anyone who has ever played with a spinning top, repeón or spinning top, will have observed how its speed varies in small proportions when it spins on an irregularly textured surface in which changes in friction occur. As in this case, the Earth and its rotation are subject to the laws of physics, and in this sense, despite the record number of July, the truth is that in the last million years the Earth has slowed down due to the friction generated by the Moon’s gravity and the generation of the tides.
However, phenomena also occur in the opposite direction. As the Director of the Australian Center of Excellence in Antarctic Science at the University of Tasmania explained, Matt Kingand the professor of the School of Geography, Planning and Spatial Sciences of the same university, Christopher Watsonin an article published in The conversation, “At the end of the last ice age, the melting of the polar ice caps reduced the surface pressure and the Earth’s mantle began to move steadily towards the poles”. This has produced that over the past 20,000 years the Earth has accelerated. “Just as a ballet dancer spins faster as she brings her arms closer to her body, the axis around which she spins, the rotational speed of our planet increases as this mantle mass gets closer to the axis of Earth. And this process shortens the days by about 0.6 milliseconds every century.”
Other factors, such as earthquakes, eruptions like those of the Tonga volcano or the weather, can also affect the length of days. “The changes may be due to an effect called The Chandler Caucus, by which the Earth’s axis of rotation changes in periods of 430 days.” However, King and Watson argue that the length of days on Earth is actually increasing, for which they still have no explanation, so the scientists postulate that the most plausible is that nothing specific has changed in or around the Earth, and that the phenomenon could simply be due to the long-term tidal effects that we mentioned a few lines ago, which operate in parallel with other periodic processes to produce a temporary change in the rate of rotation of the Earth.
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