by The earth turns faster this summer, makes the days shorter and draws the attention of scientists and timekeepers.
July 10 was the shortest day of the year so far and, according to the international earth and reference system service and the data of the international earth and reference system compiled by Timeanddate.com, took less than 24 hours less than 24 hours. On July 22nd and August 5, exceptionally short days will take place, which are currently 1.34 and 1.25 milliseconds shorter than 24 hours.
The length of a day is the time the planet needs to complete a complete rotation on its axis – 24 hours or 86,400 seconds on average. In reality, every rotation is slightly irregular due to a variety of factors, such as the gravity growth of the moon, seasonal changes in the atmosphere and the influence of the liquid core of the earth. As a result, a complete rotation usually takes a little less or a little more than 86,400 seconds – a discrepancy of only milliseconds, which has no obvious influence on everyday life.
However, these discrepancies can influence computers, satellites and telecommunications in the long run, which is why even the smallest time deviations with nuclear clocks that were introduced in 1955 are pursued. Some experts believe that this could lead to a similar scenario that resembles the Y2K problem that could bring modern civilization to a fall with modern civilization.
Atomic clocks count the vibrations of atoms that are kept in a vacuum chamber in the clock to calculate 24 hours up to a greatest degree of precision. We call the resulting time UTC or coordinated universal period based on around 450 atomic clocks and is the global standard for time measurement, as well as the time for which all of our phones and computers are defined.
An atomic clock in the time laboratory of the Physikalisch-Technische Bundesstamstalt (PTB) in Germany. These devices use lasers and atoms to calculate the time with extreme precision. – Julian Stratschulte/Bild Allianz/dpa/Getty Images
Astronomers also pursue the rotation of the earth – for example satellites that check the position of the planet relative to fixed stars – and can recognize tiny differences between the time of the atomic clocks and the time that the earth actually needs to complete a complete rotation. Last year, on July 5, 2024, the Earth experienced the shortest day, which had been recorded 65 years ago on the emergence of the nuclear clock with 1.66 milliseconds less than 24 hours.
“We have had a trend towards somewhat faster days since 1972,” said Duncan Agnew, emeritus professor of geophysics at the Scripps Institution of Oceanography and research geophysicist at the University of California in San Diego. “But there are fluctuations. It’s really like watching the stock market. There are long -term trends, and then there are summits and falls.”
After decades of relatively slow rotation, the spin of Earth in 1972 had accelerated such a delay in comparison to nuclear times that the international grounding and reference system service had prescribed the addition of a “jump in second” to the UTC. This is similar to the leap year, which adds an additional day to February every four years to take into account the discrepancy between the Gregorian calendar and the time the earth needs to complete an orbit around the sun.
The UTC has been added a total of 27 jumps since 1972, but the addition rate has increasingly slowed down due to the acceleration of the earth. In the 1970s, nine jumps were added, while no new jumps have been added since 2016.
In 2022, the General Conference voted for weight and measurements (CGPM) for the retirement of the second until 2035, which means that we may never have added another to the watches. However, if the earth rotates for a few more years, according to Agnew, a second may have to be removed from the UTC. “There has never been a negative jump,” he said, “but the likelihood of having one by 2035 is about 40%.”
What makes the earth turn faster?
The shortest changes in the rotation of the earth, said Agnew, come from the moon and the tides, which turns slower when the satellite is above the equator and faster when it is higher or lower. This effect combines the fact that naturally rotates faster during the summer earth – the result of the atmosphere itself, which slows down due to seasonal changes, such as: B. the jet current that moves north or south; The laws of physics determine that the total angle impulse of the earth and its atmosphere must remain constant, so that the rotation speed lost by the atmosphere is absorbed by the planet itself. Similarly, the liquid core of the earth has also slowed down in the past 50 years, with the solid earth accelerating around it.
By considering the combination of these effects, scientists can predict whether an upcoming day could be particularly short. “These fluctuations have short-term correlations, which means that the earth, when accelerating in one day, accelerates the next day,” said Juda Levine, physicist and fellow of the National Institute for Standards and Technology in the time and frequency department. “But this correlation disappears when you go to longer and longer intervals. When you arrive for a year, the prediction will be quite uncertain. In fact, the international grounding and reference system service does not predict any further than one year.”
The spin rate of the earth is influenced by many factors, but the moon and tides have traditionally played an important role. – NASA
A short day makes no difference, said Levine, the recent trend of shorter days is to increase the possibility of a negative jump second. “When the Leap Second system was defined in 1972, nobody really thought that the negative second would ever happen,” he noted. “It was only something that was brought to the standard because it had to be completed. Everyone assumed that only positive jumping rounds would be needed, but now the shortening of the days (negative jumps) is in danger of passing, so to speak.”
Secondly, the prospect of a negative jump throws concerns, since there are still persistent problems with positive jump after 50 years, Levine explained. “There are still places that do it wrong or do it at the wrong time or do it with the wrong number, etc.. And this is with a positive jump that has been made again and again.
Since so many fundamental technology systems on watches and time, such as telecommunications, financial transactions, electrical grids and GPS satellites, to name just a few, the Advent of the negative leap second is, according to Levine, something related to the problem of Y2K problems. The moment when the thinking of the last year in which the social date from the hunting of thinking about the just of justice is because it is in the kind of Southyday -day -day -day -day -day -day -day -Day -day -day -day -Day -day -day -day -day -day -day -day -day -Day -day -day -days day. ’99’ to ’00. ‘
The role of melting ice cream
Climate change is also a factor for the question of jumping width, but in a surprising way. While global warming had significant negative effects on earth, in our time measurement it caused it to counteract the forces that accelerate the spin of the earth. A study published last year by Agnew in the Nature magazine describes how the ice is spreading across the oceans in Antarctica and Greenland and slows down the rotation of the earth – similar to a skater that turns over the head with its arms, but turns slower when the arms are put along the body.
“If this ice had not melted, if we had no global warming, we already had a leap negatively second or we would be very close to having it,” said Agnew. According to NASA, Meltwasser from Greenland and Antarctic ice sheet has been responsible for a third of the global increase in sea level since 1993.
A look at the shoe smithy on Horseshoe Island in the Antarctic. The melting of ice here and in Greenland affects the rotation speed of the earth. – Sebnem Coskun/Anadolu Agency/Getty Images
The mass shift of this melting ice cream not only causes changes in the rotation speed of the earth, but also in its rotary axis, as under the direction of Benedikt Soy, an assistant professor at the Department of Civil, Environmental and Geomatic Engineering of the Swiss Federal Institute of Technology, Switzerland, Switzerland. If the warming continues, its effect can become dominant. “By the end of this century, the impact of climate change in a pessimistic scenario (in which humans continue to emit more greenhouse gases) could exceed the effect of the moon, which has really suppressed the rotation of the earth in the past billions,” said soy.
At the moment it is helpful to have more time to prepare for actions, since long -term predictions about the spinning behavior of the earth are uncertainty. “I think the (faster spinning) is still within reasonable limits, so it could be a natural variability,” said Soy. “Perhaps we could see another situation in a few years, and in the long term we could see how the planet slowed down again. That would be my intuition, but they never know.”
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