Wednesday, October 5

How long is a day on Earth really? | Digital Trends Spanish


As confusing and changeable as the world can be, there are some comforting certainties: the sun rises in the east, summer follows spring, and a day lasts 24 hours. Right? Unfortunately, not even these basic principles of life on Earth are set in stone. In recent years, researchers have noted that days on earth they are getting shorter, and no one knows exactly why.

The kind of shortening we’re talking about is only noticeable because of atomic clocks, which can measure time extremely precisely. Ever since scientists began using these atomic clocks to measure the length of days, the record for the shortest day ever recorded has been set at july this year.

A day is a period in which the Earth makes a complete rotation around its axis. Although this averages over 24 hours, the speed of this spin can actually increase or decrease, effectively shortening or lengthening the days. It is the increasing rate of spin of the Earth that is causing the days to grow shorter, as they generally have in the past. order of milliseconds per year since 2019.

The strange part of this story is that no one is quite sure what is causing this faster spin. The general consensus among geoscientists is that it is probably due to processes within the planet, or due to the oceans or climate. Earth isn’t the only planet with this problem either, as similar but more pronounced effects are seen on Venus, which has variable length of days due to its thick atmosphere.

On Earth, you have to consider the effect of the moon’s gravity, which creates the tides and has slowed down over time. Earth’s rotation due to friction. But there are also processes that work in the other direction to speed up your turnover.

“When the last ice age ended, the melting of the polar ice caps reduced the surface pressure, and the Earth’s mantle began to move steadily toward the poles,” explain two researchers in the field of geodesy (the science of the fundamental properties of the Earth), Matt King and Christopher Watson, in TI have Conversation. “Just as a ballet dancer spins faster as he brings his arms in toward his body, the axis around which he spins, our planet’s spin rate increases as this mantle mass approaches the axis of the Earth. Land. And this process shortens every day by about 0.6 milliseconds every century.”

Other factors like earthquakes and weather can also affect the length of days, or the changes could be due to an effect called Chandler wobble, which is where Earth’s axis of rotation shifts by small amounts. King and Watson, however, argue that the length of days on Earth is actually increasing, with long-term effects shifting from shorter to longer days from 2020.

As well as being of general interest, the exact length of days also has a practical impact, with the complex need to international leap seconds to allow for these continual changes in the Earth’s rotation.

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