Pedro Gargantilla Updated: Save Send news by mail electrónicoTu name *
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At least in theory, a globe of desktop is designed to be a sphere geometrically perfect and turn of the way, equally perfect, along an imaginary axis that connects the north pole with the south pole.
In reality, and if you go into detail, the Earth is far from being a perfect sphere, geometrically and this rotation varies slightly in a periodic manner, to be subject to multiple factors, as we will now see.
earthquakes are capable of reducing entire cities to rubble and charged in minutes thousands of lives, but its impact is not limited to this, also you can move mountains and alter the earth axis.
In April, 2015, a devastating earthquake –magnitude 7.8 in the Richter scale – rocked Nepal to such an extent that it displaced the top of mount Everest three inches toward the southwest.
If we look a little further back, the eleventh day of march in the year 2011 an earthquake of nine on the richter scale devastated the country of the rising sun. The landslide was such that in some parts of Japan, there were movements of up to four meters. The experts calculated that it was the fifth largest earthquake in the last hundred years.
This earthquake changed our earth axis in almost seventeen centimeters in the direction of 133 degrees longitude east, causing the Earth to rotate a little faster and that, in this way, to shorten the length of the day in one of eight microseconds.
despite everything, the days are longer, The truth is that it was not the first time that this happened, already in the year 2008 the people of chile suffered a terrible earthquake that moved the shaft also a few centimeters and shortened the day 1.26 microseconds.
With all these data we may think that the days are becoming shorter, however, some time ago a team of astronomers from the Royal Observatory of Greenwich was brought to light in a study that concluded that the average of each day was elongated at a speed of the 1.8 milliseconds per century.
This “stretching time” is not new, it has been produced without solution of continuity over the past twenty-seven centuries. If we do a small mathematical calculation will come to the conclusion that in order to lengthen our day in a minute we will need “only” expect to 5.2 million years.
The Moon also has its part of responsibility
According to the most precise estimates, a few billion four hundred million years, an earth day lasted only eighteen hours, despite the fact that the length of the year was similar to the current one.
The explanation of this difference is to be found in the Moon. In those times the satellite was much closer to our night sky, resulting in a faster spin on the shaft.
it Is estimated that each year the Moon is moving away lazily of us at a rate of four inches, so that the influence of its gravity is each time a little lower.
The climate change , that so much depends on the man’s hand, also has its grain of sand in the length of days. The global warming has resulted in a gradual thawing, and, consequently, in an increase in the level of the sea. This fact results in a drift of the axis of rotation of the Earth, a concept which experts have christened as “motion polar”.
In short, our little blue world is extremely fragile and there are a multitude of “insignificant” details that influence their stability and in the length of days.
M. Jara
Pedro Gargantilla is a internist in the Hospital of El Escorial (Madrid), and author of several popular books.
